Huanping Dai

Interests

Teaching

Courses taught:Cochlear ImplantsHearing SciencesHearing AidsPsychological AcousticsResearch methods & statistical inferences

Research

Mathematical Modeling of perceptual processingSignal-Detection TheorySignal processing for sensory systemExperimental methods in perception researchAttention; cognition

Courses

Scholarly Contributions

Chapters

• Dai, H. (2005). Frequency Coding and Pitch Perception. In Handbook of Hearing Sciences, edited by J. Wang, T. Jiang, & F-G. Zeng(pp 376-390.). (Chinese Science and Technology Publisher).
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  PMID: 2011448;
• Dai, H., Neely, S. T., Neff, D., & Jesteadt, W. (2001). Temporal integration models: Implications from psychometric functions for detecting level increments. In Physiological and Psychological Bases of Auditory Function. edited by D.J.Breebaart A.J.M. Houtsma, A. Kolrausch, V.F. Prijs, & R. Schoonhoven(pp 51-58). Shaker Publishing BV.
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  PMID: 2011448;
• Neely, S. T., & Dai, H. (2001). Inferring properties of IHC excitation from psychophysical growth of masking. In , in Physiological and Psychological Bases of Auditory Function. edited by D.J.Breebaart A.J.M. Houtsma, A. Kolrausch, V.F. Prijs, & R. Schoonhoven(pp 28-34.). Shaker Publishing BV.
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  PMID: 2011448;
• Dai, H. (1998). Listeners' spectral weighting functions describing the dominance region for the complex tones. In Psychophysical and Physiological Advances in Hearing, edited by A. R. Palmer, A. Rees, A. Q. Summerfield, & R. Meddies(pp 223-228.). (Whurr Publishers, London).
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  PMID: 2011448;
• Green, D. M., Dai, H., & Saberi, K. (1995). Shape discrimination of spectra with various bandwidths. In Advances in Hearing Research, edited by G. A. Manley, G. M. Klump, C. Koppl, H. Fastl, & H. Oeckinghaus(pp 501-511). (World Scientific).
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  PMID: 2011448;
• Green, D. M., & Dai, H. (1992). Temporal relations in profile comparisons. In Auditory Physiology and Perception, edited by Y. Cazals, L. Demany, & K. Horner(pp 471-478). Pergamon Press.
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  PMID: 2011448;
• Feng, R., & Dai, H. (1987). Progress of theoretical studies in ultrasonic biophysics. In The Biomedical Ultrasound, Ruo Feng (ed)(pp 1-11). Nanjing University Press.

Journals/Publications

• Dai, H. (2022). Discrimination thresholds for interaural-time differences and interaural-level differences in naïve listeners: Sex differences and learning. Hearing Research, vol. 424, 1-8..
• Dai, H. (2017). On averaging multiple estimates of decision weights within or across listeners. The Journal of the Acoustical Society of America, 142(6), 3781.
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  As a practical guide, a formula is provided for averaging multiple estimates of decision weights, for the purpose of improving the accuracy and reliability of the final estimate of decision weights. The averaging over multiple weight estimates can take place either within or across listeners.
• Sandoval, M., Patterson, D., Dai, H., Vance, C. J., & Plante, E. (2017). Neural Correlates of Morphology Acquisition through a Statistical Learning Paradigm. FRONTIERS IN PSYCHOLOGY, 8.
• Sandoval, M., Patterson, D., Dai, H., Vance, C. J., & Plante, E. (2017). Neural Correlates of Morphology Acquisition through a Statistical Learning Paradigm. Frontiers in psychology, 8, 1234.
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  The neural basis of statistical learning as it occurs over time was explored with stimuli drawn from a natural language (Russian nouns). The input reflected the "rules" for marking categories of gendered nouns, without making participants explicitly aware of the nature of what they were to learn. Participants were scanned while listening to a series of gender-marked nouns during four sequential scans, and were tested for their learning immediately after each scan. Although participants were not told the nature of the learning task, they exhibited learning after their initial exposure to the stimuli. Independent component analysis of the brain data revealed five task-related sub-networks. Unlike prior statistical learning studies of word segmentation, this morphological learning task robustly activated the inferior frontal gyrus during the learning period. This region was represented in multiple independent components, suggesting it functions as a network hub for this type of learning. Moreover, the results suggest that subnetworks activated by statistical learning are driven by the nature of the input, rather than reflecting a general statistical learning system.
• Buss, E., Dai, H., & Hall, J. W. (2015). Effect of stimulus bandwidth and duration on monaural envelope correlation perception. The Journal of the Acoustical Society of America, 137(1), EL51-7.
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  Monaural envelope correlation perception is the ability to discriminate between stimuli composed of two or more bands of noise based on envelope correlation. Sensitivity decreases as stimulus bandwidth is reduced below 100 Hz. The present study manipulated stimulus bandwidth (25-100 Hz) and duration (25-800 ms) to evaluate whether performance of highly trained listeners is limited by the number of inherent modulation periods in each presentation. Stimuli were two bands of noise, separated by a 500-Hz gap centered on 2250 Hz. Performance improved reliably with increasing numbers of envelope modulation periods, although there were substantial individual differences.
• Dai, H., & Buss, E. (2015). Optimal integration of independent observations from Poisson sources. The Journal of the Acoustical Society of America, 137(1), EL20-5.
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  The optimal integration of information from independent Poisson sources (such as neurons) was analyzed in the context of a two-interval, forced-choice detection task. When the mean count of the Poisson distribution is above 1, the benefit of integration is closely approximated by the predictions based on the square-root law of the Gaussian model. When the mean count falls far below 1, however, the benefit of integration clearly exceeds the predictions based on the square-root law.
• Dai, H., & Micheyl, C. (2015). A general formula for computing maximum proportion correct scores in various psychophysical paradigms with arbitrary probability distributions of stimulus observations. Attention, perception & psychophysics, 77(4), 1448-60.
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  Proportion correct (Pc) is a fundamental measure of task performance in psychophysics. The maximum Pc score that can be achieved by an optimal (maximum-likelihood) observer in a given task is of both theoretical and practical importance, because it sets an upper limit on human performance. Within the framework of signal detection theory, analytical solutions for computing the maximum Pc score have been established for several common experimental paradigms under the assumption of Gaussian additive internal noise. However, as the scope of applications of psychophysical signal detection theory expands, the need is growing for psychophysicists to compute maximum Pc scores for situations involving non-Gaussian (internal or stimulus-induced) noise. In this article, we provide a general formula for computing the maximum Pc in various psychophysical experimental paradigms for arbitrary probability distributions of sensory activity. Moreover, easy-to-use MATLAB code implementing the formula is provided. Practical applications of the formula are illustrated, and its accuracy is evaluated, for two paradigms and two types of probability distributions (uniform and Gaussian). The results demonstrate that Pc scores computed using the formula remain accurate even for continuous probability distributions, as long as the conversion from continuous probability density functions to discrete probability mass functions is supported by a sufficiently high sampling resolution. We hope that the exposition in this article, and the freely available MATLAB code, facilitates calculations of maximum performance for a wider range of experimental situations, as well as explorations of the impact of different assumptions concerning internal-noise distributions on maximum performance in psychophysical experiments.
• Wright, B. A., & Dai, H. (2013). Tuning in the time domain revealed through detection of auditory signals of unexpected duration or presentation time. Proceedings of Meetings on Acoustics, 19.
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  Abstract: Bert Scharf was interested in how expectation affects auditory performance. He explored this question using the probe-signal method of Greenberg and Larkin, in which the listener is led to expect a particular stimulus but is occasionally presented with an unexpected but equally detectable one. The detectability of unexpected stimuli provides insight into the listener's template for the expected stimulus. Bert's expectation research, which focused on the frequency domain, inspired us to extend the inquiry to the time domain. We have seen that signal detection can be quite poor for signals of unexpected duration as well as for signals presented at unexpected times, indicating that listeners attend selectively to these two temporal aspects of sound. However, this temporal tuning is much broader for starting time (hundreds of milliseconds) than for signal duration (can be < 25 ms). Thus, it appears that listeners can select the template for signal detection with considerable accuracy, but do not apply the selected template strictly to the expected starting time of the signal. We are grateful to Bert for his mentorship and keen interest in this topic. © 2013 Acoustical Society of America.
• Dai, H., & Micheyl, C. (2012). Measuring decision weights in recognition experiments with multiple response alternatives: Comparing the correlation and multinomial-logistic- regression methods. Journal of the Acoustical Society of America, 132(5), 3418-3427.
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  PMID: 23145622;PMCID: PMC3505214;Abstract: Psychophysical reverse-correlation methods allow researchers to gain insight into the perceptual representations and decision weighting strategies of individual subjects in perceptual tasks. Although these methods have gained momentum, until recently their development was limited to experiments involving only two response categories. Recently, two approaches for estimating decision weights in m-Alternative experiments have been put forward. One approach extends the two-category correlation method to m > 2 alternatives; the second uses multinomial logistic regression (MLR). In this article, the relative merits of the two methods are discussed, and the issues of convergence and statistical efficiency of the methods are evaluated quantitatively using Monte Carlo simulations. The results indicate that, for a range of values of the number of trials, the estimated weighting patterns are closer to their asymptotic values for the correlation method than for the MLR method. Moreover, for the MLR method, weight estimates for different stimulus components can exhibit strong correlations, making the analysis and interpretation of measured weighting patterns less straightforward than for the correlation method. These and other advantages of the correlation method, which include computational simplicity and a close relationship to other well-established psychophysical reverse-correlation methods, make it an attractive tool to uncover decision strategies in m-Alternative experiments. © 2012 Acoustical Society of America.
• Dai, H., & Micheyl, C. (2012). Separating the contributions of primary and unwanted cues in psychophysical studies. Psychological Review, 119(4), 770-788.
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  PMID: 22844984;PMCID: PMC3749307;Abstract: A fundamental issue in the design and the interpretation of experimental studies of perception relates to the question of whether the participants in these experiments could perform the perceptual task assigned to them using another feature, or cue, than that intended by the experimenter. An approach frequently used by auditory- and visual-perception researchers to guard against this possibility involves applying random variations to the stimuli across presentations or trials so as to make the "unwanted" cue unreliable for the participants. However, the theoretical basis of this widespread practice is not well developed. In this article, we describe a 2-channel model based on general principles of psychophysical signal detection theory, which can be used to assess the respective contributions of the unwanted cue and of the primary cue to performance or thresholds measured in perceptual discrimination experiments involving stimulus randomization. Example applications of the model to the analysis of results obtained in representative studies from the auditory- and visual-perception literature are provided. In several cases, the results of the model-based analyses indicate that the effectiveness of the randomization procedure was less than originally assumed by the authors of these studies. These findings underscore the importance of quantifying the potential influence of unwanted cues on the results of psychophysical experiments, even when stimulus randomization is used. © 2012 American Psychological Association.
• Dai, H., & Micheyl, C. (2011). Psychometric functions for pure-tone frequency discrimination. Journal of the Acoustical Society of America, 130(1), 263-272.
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  PMID: 21786896;PMCID: PMC3155586;Abstract: The form of the psychometric function (PF) for auditory frequency discrimination is of theoretical interest and practical importance. In this study, PFs for pure-tone frequency discrimination were measured for several standard frequencies (200-8000 Hz) and levels [35-85 dB sound pressure level (SPL)] in normal-hearing listeners. The proportion-correct data were fitted using a cumulative-Gaussian function of the sensitivity index, d′, computed as a power transformation of the frequency difference, Δf. The exponent of the power function corresponded to the slope of the PF on log(d′)-log(Δf) coordinates. The influence of attentional lapses on PF-slope estimates was investigated. When attentional lapses were not taken into account, the estimated PF slopes on log(d′)-log(Δf) coordinates were found to be significantly lower than 1, suggesting a nonlinear relationship between d′ and Δf. However, when lapse rate was included as a free parameter in the fits, PF slopes were found not to differ significantly from 1, consistent with a linear relationship between d′ and Δf. This was the case across the wide ranges of frequencies and levels tested in this study. Therefore, spectral and temporal models of frequency discrimination must account for a linear relationship between d′ and Δf across a wide range of frequencies and levels. © 2011 Acoustical Society of America.
• Dai, H., & Richards, V. M. (2011). On the theoretical error bound for estimating psychometric functions. Attention, Perception, and Psychophysics, 73(3), 919-926.
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  PMID: 21264715;Abstract: The theoretical limits to the amount of error, or the Cramer-Rao bounds, were derived for estimating psychometric functions. These theoretical error bounds were compared with the variability of psychometric functions estimated from human as well as computer-simulated observers. For the simulated observers, due to the limited efficiency of the sampling strategies, including the placement of the signals and the distribution of the trials, the variances of the estimated parameters are seven times the theoretical bound for threshold and 22 times that for slope. For the human observers, the variance is 18 times the theoretical bounds for threshold and 80 times that for slope. Therefore, a major portion of the variances (60% for threshold and 73% for slope) for the human observers is associated with factors other than sampling strategies. Further improvement of the accuracy for estimating psychometric functions will depend on not only optimizing the sampling strategy, but also better understanding the various sources of error related to the behavior of human observers. © Psychonomic Society, Inc. 2010.
• Dai, H. (2010). Harmonic pitch: Dependence on resolved partials, spectral edges, and combination tones. Hearing Research, 270(1-2), 143-150.
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  PMID: 20709166;PMCID: PMC3703502;Abstract: Perceptual weights were estimated in a pitch-comparison experiment to assess the relative influences of individual partial tones on listeners' pitch judgments. The stimuli were harmonic sounds (F0=200Hz) with partials up to the 12th. Low-numbered partials were removed step-by-step, so that the remaining higher-numbered partials would have a better chance of showing any effect. The individual frequencies of the partials were perturbed randomly on each stimulus presentation, and weights were estimated as the correlation coefficients between the frequency perturbations and the listeners' responses. When the harmonic sounds contained all twelve partials, the listeners depended mostly on the low-numbered, resolved partials within the well-established dominance region. As the low-numbered partials were taken out of the dominance region, the listeners mostly listened to the lowest and highest partials at the spectral edges. For one listener, such an edge-listening strategy took the form of relying on nonlinear combination tones. Overall, there was no indication of any influence on pitch from unresolved partials, thus no evidence of contribution to pitch from temporal cues carried by this group of partials. The estimated patterns of weights were well described by the predictions of Goldstein's optimal-processor model. The predicted weights were inversely proportional to the amount of error for estimating the individual frequencies of the partials. The agreement between the predicted and measured weights suggests that, for harmonic sounds, partials whose frequencies are perceived with the best precision will likely have the greatest influence on perceived pitch. © 2010 Elsevier B.V.
• Dai, H., & Micheyl, C. (2010). On the choice of adequate randomization ranges for limiting the use of unwanted cues in same-different, dual-pair, and oddity tasks. Attention, Perception, and Psychophysics, 72(2), 538-547.
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  PMID: 20139466;PMCID: PMC3018147;Abstract: A major concern when designing a psychophysical experiment is that participants may use a stimulus feature (cue) other than that intended by the experimenter. One way to avoid this problem is to apply random variations to the corresponding feature across stimulus presentations to make the unwanted cue unreliable. An important question facing experimenters who use this randomization (roving) technique is how large the randomization range should be to ensure that the participants cannot achieve a certain proportion correct by using the unwanted cue, while at the same time avoiding unnecessary interference of the randomization with task performance. Previous researchers have provided formulas for the selection of adequate randomization ranges in yes-no and multiplealternative forced choice tasks. In this article, we provide figures and tables that can be used to select randomization ranges that are better suited to experiments involving a same-different, dual-pair, or oddity task. © 2010 The Psychonomic Society, Inc.
• Dai, H., & Micheyl, C. (2010). Psychophysical reverse correlation with multiple response alternatives. Journal of Experimental Psychology: Human Perception and Performance, 36(4), 976-993.
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  PMID: 20695712;PMCID: PMC3158580;Abstract: Psychophysical reverse-correlation methods such as the " classification image" technique provide a unique tool to uncover the internal representations and decision strategies of individual participants in perceptual tasks. Over the past 30 years, these techniques have gained increasing popularity among both visual and auditory psychophysicists. However, thus far, principled applications of the psychophysical reverse-correlation approach have been almost exclusively limited to two-alternative decision (detection or discrimination) tasks. Whether and how reverse-correlation methods can be applied to uncover perceptual templates and decision strategies in situations involving more than just two response alternatives remain largely unclear. Here, the authors consider the problem of estimating perceptual templates and decision strategies in stimulus identification tasks with multiple response alternatives. They describe a modified correlational approach, which can be used to solve this problem. The approach is evaluated under a variety of simulated conditions, including different ratios of internal-to-external noise, different degrees of correlations between the sensory observations, and various statistical distributions of stimulus perturbations. The results indicate that the proposed approach is reasonably robust, suggesting that it could be used in future empirical studies. © 2010 American Psychological Association.
• Dai, H., & Kidd, G. (2009). Limiting unwanted cues via random rove applied to the yes-no and multiple-alternative forced choice paradigms. Journal of the Acoustical Society of America, 126(2), EL62-EL67.
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  PMID: 19640017;PMCID: PMC2728343;Abstract: When a random rove is used in a perceptual task to control the influence of an unwanted cue that may confound the decision strategy of primary interest, the effectiveness of the rove is determined by its range. Green [Profile Analysis (Oxford University Press, Oxford, 1988)] provided a formula which allows experimenters to determine the roving range required to ensure that the listeners relying on the unwanted cue cannot exceed a pre-defined percentage of correct responses in a two-interval, two-alternative forced-choice experiment. Here, Green's analysis is extended to the yes-no and m -alternative, forced-choice paradigms (m>2). © 2009 Acoustical Society of America.
• Micheyl, C., & Dai, H. (2009). Likelihood ratio, optimal decision rules, and relationship between proportion correct and d' in the dual-pair AB-versus-BA identification paradigm. Attention, Perception, and Psychophysics, 71(6), 1426-1433.
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  PMID: 19633356;PMCID: PMC2811854;Abstract: The equal-variance Gaussian signal detection theory (SDT) decision model for the dual-pair (4IAX) change-detection paradigm has been described in earlier publications. In this research article, we consider the equal-variance Gaussian SDT model for the related 4IAX AB-versus-BA identification paradigm. The likelihood ratios, optimal decision rules, receiver-operating characteristics (ROCs), and relationships between d' and proportion correct (PC) are analyzed for two special cases: that of statistically independent observations, which typically applies in constant-stimuli experiments, and that of highly correlated observations, which typically applies in experiments where stimuli are roved widely across trials or pairs. A surprising outcome of this analysis is that, although these two situations lead to different optimal decision rules, the predicted ROCs and PC responses for these two cases are not substantially different and are either identical to or similar to those observed in the basic yes-no paradigm. Supplemental materials for this study can be downloaded from app.psychonomic-journals.org/content/supplemental. © 2009 The Psychonomic Society, Inc.
• Dai, H. (2008). On suppressing unwanted cues via randomization. Perception and Psychophysics, 70(7), 1379-1382.
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  PMID: 18927020;Abstract: In certain perceptual discrimination tasks, a change in a particular stimulus variable can be perceived as changes along multiple perceptual dimensions. If the study is primarily concerned with a particular perceptual dimension or cue, it is important that the experimenter keep the influences of the other unwanted but correlated perceptual cues under control. One way to accomplish this objective is to randomize the stimuli along the stimulus dimensions primarily associated with these unwanted cues, making them unreliable as a basis for the discrimination. This theoretical note presents a mathematical proof that a uniform randomization is the most effective way of suppressing unwanted cues. Copyright 2008 Psychonomic Society, Inc.
• Dai, H., & Dai, H. -. (2008). On suppressing unwanted cues via randomization. Perception & psychophysics, 70(7).
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  In certain perceptual discrimination tasks, a change in a particular stimulus variable can be perceived as changes along multiple perceptual dimensions. If the study is primarily concerned with a particular perceptual dimension or cue, it is important that the experimenter keep the influences of the other unwanted but correlated perceptual cues under control. One way to accomplish this objective is to randomize the stimuli along the stimulus dimensions primarily associated with these unwanted cues, making them unreliable as a basis for the discrimination. This theoretical note presents a mathematical proof that a uniform randomization is the most effective way of suppressing unwanted cues.
• Micheyl, C., & Dai, H. (2008). A general area theorem for the same-different paradigm. Perception and Psychophysics, 70(5), 761-764.
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  PMID: 18613624;Abstract: According to a well-known theorem in psychophysics (Green & Swets, 1966), the area under the receiver operating characteristic (ROC) for the yes-no paradigm equals the proportion of correct responses of an unbiased observer in the two-interval, two-alternative, forced choice paradigm (2I2AFC). Here, we demonstrate a similar relationship between the ROC area in the two-interval same-different (AX or 2IAX) paradigm, and the proportion correct in the four-interval same-different (4IAX, also known as dual-pair comparison) paradigm. The theorem demonstrated here is general, in the sense that it does not require that the sensory observations have a specific distribution (e.g., Gaussian), or that they be statistically independent. Copyright 2008 Psychonomic Society, Inc.
• Dai, H., & Hou, Z. (2004). New feedback-cancellation algorithm reported to increase usable gain. Hearing Journal, 57(5), 44-46.
• Hou, Z., & Dai, H. (2004). An online hearing-screening test. The Hearing Review, 11(11), 48-49.
• Huanping, D. (2000). On the relative influence of individual harmonics on pitch judgment. Journal of the Acoustical Society of America, 107(2), 953-959.
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  PMID: 10687704;Abstract: Spectral weighting functions were estimated in a pitch-comparison task to assess the relative influence of individual harmonics on listeners' pitch judgment. The stimuli were quasi-harmonic complex tones composed of the first 12 components, with fundamental frequencies ranging from 100 to 800 Hz. On each stimulus presentation the frequency of each harmonic was randomly jittered by a small amount. The perceptual weight for each harmonic was calculated as the correlation coefficient between the binary responses of the listener and the frequency jitters for that harmonic. Although in general the present results conform to previous ones showing the predominant role of several low-ranked harmonics, discrepancies exist in details. Contrary to some previous reports that the dominant harmonics were of fixed harmonic ranks regardless of their frequencies, the current results showed that the dominant harmonics were best described as close to a fixed absolute frequency of 600 Hz. (C) 2000 Acoustical Society of America.
• Dai, H., & Wright, B. A. (1999). Predicting the detectability of tones with unexpected durations. Journal of the Acoustical Society of America, 105(3), 2043-2046.
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  PMID: 10089621;Abstract: This letter supplies the predictions of the energy-detector model and two versions of the multiple-look model for detecting tones with unexpected durations.
• Wright, B. A., & Dai, H. (1998). Detection of sinusoidal amplitude modulation at unexpected rates. Journal of the Acoustical Society of America, 104(5), 2991-2996.
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  PMID: 9821343;Abstract: The detectability of sinusoidal amplitude modulation at unexpected modulation rates was assessed using a probe-signal method. With this method, three listeners were led to expect a target modulation rate (4, 32, or 256 Hz) by presenting the signal most often at that rate, and sensitivity to modulation at six other unexpected rates between 4 and 256 Hz was measured via occasionally presented probe modulation rates. The modulation phase was random on each two-interval forced-choice trial and the overall level of the 500-ms broadband carder was randomly varied between 55 and 75 dB SPL across intervals. The modulation depth at each rate was set so that the modulation was detected on about 90% of the trials when only that rate was presented. Performance at the unexpected rates depended upon the target rate. For the 4- Hz target, modulation at all rates was detected on about 80% of the trials. For the 32- and 256-Hz targets, unexpected modulation rates of 16 Hz and above were detected on 80%-90% of the trials, but modulation rates below 16 Hz were detected nearly at chance. The influence of expectation of modulation rate on the detection of sinusoidal amplitude modulation is not readily predicted by current models of modulation detection.
• Dai, H., & Wright, B. A. (1996). The lack of frequency dependence of thresholds for short tones in continuous broadband noise. Journal of the Acoustical Society of America, 100(1), 467-472.
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  Abstract: The threshold for detecting a tonal signal in a continuous broadband noise increases with increasing signal frequency for long, but not for short signal durations. This is revealed by an analysis of previous studies, and confirmed with three subjects in the present experiment using signals covering a frequency range from 125 to 4000 Hz and a duration range from 2 to 1000 ms. The relationship between threshold and signal frequency for a wide range of signal durations is explained by an energy-detector model in which the time window is assumed to match the signal duration and the predicted signal level is adjusted to compensate for the loss of signal energy due to spectral spread at short durations.
• Dai, H., Nguyen, Q., & Green, D. M. (1996). Decision rules of listeners in spectral-shape discrimination with or without signal-frequency uncertainty. Journal of the Acoustical Society of America, 99(4 I), 2298-2306.
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  PMID: 8730076;Abstract: A correlation technique was used to assess the decision rules of three listeners in two cases of spectral-shape discrimination tasks. In one case the signal frequency was fixed, and in the other it was randomly varied within each block of trials. In order to estimate the decision rule of the listeners, the experimenter superimposed random level perturbations on each frequency component upon each stimulus presentation. Over many trials, correlation coefficients were computed between the random perturbations and the binary responses of the listeners, and were expressed as a function of signal level. For both the fixed- and random-signal cases, the measured correlation functions were in reasonably good agreement with those predicted based on the likelihood-ratio decision rules. Thus the listeners appeared to use information nearly optimally in discriminating spectral shapes. This investigation demonstrated that the correlation technique can be used to reveal the decision rules for cases where the decision statistics are nonlinear functions of the observations.
• Dai, H., Nguyen, Q., Kidd Jr., G., Feth, L. L., & Green, D. M. (1996). Phase independence of pitch produced by narrow-band sounds. Journal of the Acoustical Society of America, 100(4), 2349-2351.
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  PMID: 8865642;Abstract: Three listeners matched the pitch of a simple tone to that of narrow- band complex signals having different phases. The pitch matches were independent of the phases; the frequency of the simple tone approximately equaled the center of gravity of the power spectrum of each complex signal. This result is inconsistent with a model that calculates the pitch of a waveform as the average of instantaneous frequency weighted by the envelope of the waveform.
• Dai, H., Versfeld, N. J., & Green, D. M. (1996). The optimum decision rules in the same-different paradigm. Perception & Psychophysics, 58(1), 1-9.
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  Abstract: In this paper we derive the optimum (likelihood-ratio) decision statistic for a same-different paradigm. The likelihood ratio is dependent on the degree of correlation between the two observations on each trial. For the two extreme cases in which the observations are either independent or highly correlated, the optimum decision rule is identical to each of two previously suggested decision rules. For these two cases, the receiver-operating characteristic (ROC) curves are calculated. Finally, an experimental procedure is suggested for assessing the decision rule actually used by the observer in a same-different task. © 1996 Psychonomic Society, Inc.
• Versfeld, N. J., Dai, H., & Green, D. M. (1996). The optimum decision rules for the oddity task. Perception and Psychophysics, 58(1), 10-21.
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  PMID: 8668510;Abstract: This paper presents the optimum decision rule for an m-interval oddity task in which m-1 intervals contain the same signal and one is different or odd. The optimum decision rule depends on the degree of correlation among observations. The present approach unifies the different strategies that occur with "roved" or "fixed" experiments (Macmillan & Creelman, 1991, p. 147). It is shown that the commonly used decision rule for an m-interval oddity task corresponds to the special case of highly correlated observations. However, as is also true for the same-different paradigm, there exists a different optimum decision rule when the observations are independent. The relation between the probability of a correct response and d′ is derived for the three-interval oddity task. Tables are presented of this relation for the three-, four-, and five-interval oddity task. Finally, an experimental method is proposed that allows one to determine the decision rule used by the observer in an oddity experiment.
• Dai, H. (1995). On measuring psychometric functions: A comparison of the constant-stimulus and adaptive up-down methods. Journal of the Acoustical Society of America, 98(6), 3135-3139.
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  PMID: 8550938;Abstract: Psychometric functions were obtained using the conventional constant- stimulus method and an adaptive up-down method, for both computer-simulated and human observers. Except when the stimuli are closely placed, psychometric functions obtained with the adaptive method are as accurate as those obtained with the constant-stimulus method. Empirically, the adaptive method has some potential advantages owing to its ability to automatically concentrate the trials within the dynamic range of the psychometric function. It needs no pilot measurements for setting the signals as required by the constant- stimulus method. Furthermore, following a marked change in the underlying psychometric function, the distribution of the trials is automatically readjusted. Thus, on the basis of empirical considerations, the adaptive method is a better choice than the constant-stimulus method for measuring psychometric functions.
• Dai, H., & Wright, B. A. (1995). Detecting signals of unexpected or uncertain durations. Journal of the Acoustical Society of America, 98(2 I), 798-806.
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  PMID: 7642818;Abstract: Expectation of signal duration influences the signal detectability. This is demonstrated in two experiments in which percent correct was measured for both tonal and noise signals whose durations were either unexpected or uncertain. In both experiments, the signal at each duration was set to have a d' of about 1.5 when that duration was presented alone and expected. When the six subjects were led to expect a short- or a long-duration signal using the probe-signal method, the detectability of signals decreased to near chance as the signal duration deviated from the expected value (experiment 1). When the subjects were led to expect a range of durations, the detectability was only slightly worse than when each signal was presented alone (experiment 2). Those results suggest that listeners adjust their temporal-integration intervals according to the demand of the specific task. Finally, the results obtained with the noise signal were analyzed using the multiple-look model and a modified energy-detector model. Assuming that the integration interval is matched to the expected signal duration, both models predict the detection of signals having unexpected durations reasonably well. Both models, however, fail to predict the small effect of duration uncertainty.
• Dai, H., Nguyen, Q. T., & Green, D. M. (1995). A two-filter model for frequency discrimination. Hearing Research, 85(1-2), 109-114.
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  PMID: 7559165;Abstract: In this paper, we explore a two-filter model, the simplest version of multi-channel models for frequency discrimination of simple tones. According to this model, frequency discrimination is based on a change in the relative output levels of two auditory filters, one centered below and the other above the frequency of the tone. This idea can explain the experimental results that frequency discrimination is relatively unaffected by randomization of stimulus level. Moreover, it suggests a close relationship between the ability of listeners to perform frequency discrimination of simple tones and spectral-shape discrimination of two-tone complexes. The ability of three listeners to perform these two tasks was measured at six frequencies (from 0.25 to 8 kHz). The results from the spectral-shape-discrimination task were used to predict frequency-difference limens. There was a high correlation between obtained and predicted values. © 1995.
• Kidd Jr., G., Mason, C. R., & Dai, H. (1995). Discriminating coherence in spectro-temporal patterns. Journal of the Acoustical Society of America, 97(6), 3782-3790.
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  PMID: 7790656;Abstract: This study examined the ability of trained listeners to discriminate coherent components in randomly varying spectral patterns. In each observation interval, the listener was presented with a sequence of bursts of multitone complexes having a fixed number of tones (m) in each burst. In the standard interval, the frequency of each tone in every burst was chosen randomly between 200 and 5000 Hz. In the signal interval, the frequencies of n tones were repeated throughout the burst sequence while the remaining m-n tones were chosen at random. The n tones were coherent in the sense that they were perceived as 'sticking together' to form a pattern. The listener's task was to discriminate which burst sequence contained the n components. The results indicated that discrimination improved with increasing n/m, with increasing number of bursts per interval, and declined as the coherent components were increasingly perturbed in frequency. Further, for a fixed value of the ratio n/m discriminability was relatively independent of m. A model incorporating multichannel filtering and an optimum decision rule was reasonably successful in accounting for the experimental results.
• Dai, H. (1994). Signal-frequency uncertainty in spectral-shape discrimination: Psychometric functions. Journal of the Acoustical Society of America, 96(3), 1388-1396.
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  PMID: 7963004;Abstract: Psychometric functions were measured for spectral-shape discrimination (profile analysis) with the signal frequency either fixed, what we call the signal-known condition, or randomly varied, what we call the signal-unknown condition. The functions were obtained using an adaptive, up-down procedure. In the signal-unknown condition, independent tracks for each signal frequency were interleaved within the same block of trials. The mean slope of the psychometric function [k in log d' = k log ΔL + C, where ΔL = 20 log(1 + Δp/p)] was 1.13 for the signal-known conditions and 1.19 for the signal- unknown condition. The mean signal-to-standard ratio at threshold (Pc = 79.4%) obtained in the signal-unknown condition was 3 to 4 dB higher than that obtained in the signal-known conditions. The psychometric functions of the ideal observer were derived for both the signal-known and signal-unknown conditions. A comparison of the measured and derived psychometric functions suggests that the internal noise component that is statistically independent across frequency channels contributes minimally to the total (internal and external) noise sources that are involved in the decision process.
• Sorkin, R. D., & Dai, H. (1994). Signal Detection Analysis of the Ideal Group. Organizational Behavior and Human Decision Processes, 60(1), 1-13.
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  Abstract: Theorems derived from the Theory of Signal Detectability are applied to the group decision problem. These theorems specify the behavior of the Ideal Group - the group having the highest achievable detection performance given an array of members with specified individual indices of detectability. Equations are provided for relating group performance to (1) the size of the group, (2) the detectability indices of the individual members, and (3) the correlation between member observations of the stimulus. The efficiency of real groups, such as juries and committees, is briefly discussed. © 1994 Academic Press. All rights reserved.
• Wright, B. A., & Dai, H. (1994). Detection of unexpected tones in gated and continuous maskers. Journal of the Acoustical Society of America, 95(2), 939-948.
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  PMID: 8132908;Abstract: The effect of gating a wideband masker on the detectability of tones having unexpected frequencies was assessed using a probe-signal method. This method leads the listener to expect a target frequency by presenting the signal most often at that frequency, and measures sensitivity to other unexpected frequencies via occasionally presented probe tones. For 295-ms signals, the probe-signal contours (percent correct as a function of probe frequency) of two of four subjects were considerably broader for a 295-ms masker than for a continuous masker. For 5-ms signals, the probe-signal contours of four of five subjects were quite broad and similar for both gated and continuous maskers. When the probe-signal contours were expressed as the attenuation in decibels of the probes, the resulting 'probe-signal filters' were frequently broader than auditory filters measured using notched noise in the same subjects. This suggests that subjects may monitor multiple auditory filters under some conditions in the probe-signal task. Signal threshold tended to be higher for conditions showing wider probe-signal filters, indicating a potential link between changes in signal threshold due to masker gating and the number of frequency channels that are monitored.
• Wright, B. A., & Dai, H. (1994). Detection of unexpected tones with short and long durations. Journal of the Acoustical Society of America, 95(2), 931-938.
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  PMID: 8132907;Abstract: The detectability of short and long unexpected tones masked by a continuous wideband noise was assessed using a probe-signal method. This method leads the listener to expect a target frequency by presenting the signal most often at that frequency, and only occasionally at other unexpected probe frequencies. The probe-signal contour (percent correct as a function of probe frequency) was considerably broader with 5-ms than with 295-ms signals. However, auditory filter shapes measured using the notched- noise technique were very similar for those two signal durations, indicating that the results obtained in the probe-signal conditions do not simply reflect peripheral frequency selectivity. Further supporting this interpretation, probe tones having the same frequency but a different duration from the target were poorly detected. It is proposed that the subject listens through a time-frequency window whose location and shape in the time-frequency plane is determined by the duration and frequency of the target.
• Dai, H. (1993). On the pitch of two-tone complexes. Journal of the Acoustical Society of America, 94(2 I), 730-734.
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  PMID: 8370878;Abstract: The predictions of two models for the pitch of two-tone complexes were compared to pitch matching results obtained in a previous study [Feth, O'Malley, and Ramsey, J. Acoust. Soc. Am. 72, 1403-1412 (1982)] and the present study. In one model, the pitch value of a waveform was calculated from the envelope-weighted average of instantaneous frequency of the waveform (the EWAIF model). In the other model, the pitch value was calculated from the squared-envelope-weighted average of instantaneous frequency (the SEWAIF model). The SEWAIF model better predicts the data.
• Dai, H., & Green, D. M. (1993). Discrimination of spectral shape as a function of stimulus duration. Journal of the Acoustical Society of America, 93(2), 957-965.
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  PMID: 8445130;Abstract: Thresholds for discriminating the changes in the spectral shape of simultaneously presented components (profile analysis) are measured as a function of stimulus duration for various complex stimuli. For all stimuli, the threshold decreases with increasing duration until a transition time is reached, and thereafter the threshold remains constant. The amount of change in threshold and the value of transition time appear to be greater for complexes having narrower frequency spacing of the components. The results can be accounted for, at least qualitatively, by assuming that the bandwidth of the auditory filters decreases after the onset of the stimulus.
• Kidd Jr., G., & Dai, H. (1993). A composite randomization procedure for measuring spectral shape discrimination. Journal of the Acoustical Society of America, 94(3 I), 1275-1280.
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  PMID: 8408967;Abstract: In studies of auditory profile analysis [D. M. Green, Profile Analysis: Auditory Intensity Discrimination (Oxford U. P., New York, 1988)], the sounds are presented at random levels to discourage the listener from basing the discrimination on a difference in absolute level rather than on a difference in the shape of the spectrum. A difference in absolute level, however, can still provide an effective discrimination cue if the difference is comparable to the range of randomization. Using enormous ranges of random levels is not desirable, because it is distracting to normal listeners and may exceed the dynamic range of hearing for listeners with hearing loss. This article describes a new experimental procedure which permits the experimenter to greatly reduce the range of level randomization in roving-level tasks.
• Dai, H., & Green, D. M. (1992). Auditory intensity perception: Successive versus simultaneous, across- channel discriminations. Journal of the Acoustical Society of America, 91(5), 2845-2854.
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  PMID: 1629477;Abstract: This study measures the ability of observers to compare the intensities of two stimuli occupying different frequency regions. It includes three experiments, each experiment having two conditions. In one condition, the two stimuli to be compared were presented simultaneously within each interval; this condition has been called profile analysis. In the other condition, the two stimuli were presented successively within each interval. Because the overall level of the stimuli was randomized between intervals, the observers were encouraged to compare the intensities of the two stimuli within each observation interval rather than between intervals. The stimuli were two simple tones in experiment 1 and two tonal complexes in both experiments 2 and 3. The stimuli used in experiments 2 and 3 differed in frequency. The results show that simultaneous comparisons are superior to successive comparisons. For simple tones, the difference in threshold is about 8 dB; for complexes with 10 to 11 components, the difference in threshold is about 15 dB. These differences can be explained by assuming that internal noises in different channels were partially correlated when stimuli in those channels were presented simultaneously and were independent when the stimuli were presented successively. Cancellation of the correlated noise is therefore possible with simultaneous comparisons, making such discrimination better than that achievable with successive comparisons.
• Dai, H., & Green, D. M. (1992). Spectral and temporal weights in spectral shape discrimination. Journal of the Acoustical Society of America, 92, 1346-1355.
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  PMID: 1629477;Abstract: This study measures the ability of observers to compare the intensities of two stimuli occupying different frequency regions. It includes three experiments, each experiment having two conditions. In one condition, the two stimuli to be compared were presented simultaneously within each interval; this condition has been called profile analysis. In the other condition, the two stimuli were presented successively within each interval. Because the overall level of the stimuli was randomized between intervals, the observers were encouraged to compare the intensities of the two stimuli within each observation interval rather than between intervals. The stimuli were two simple tones in experiment 1 and two tonal complexes in both experiments 2 and 3. The stimuli used in experiments 2 and 3 differed in frequency. The results show that simultaneous comparisons are superior to successive comparisons. For simple tones, the difference in threshold is about 8 dB; for complexes with 10 to 11 components, the difference in threshold is about 15 dB. These differences can be explained by assuming that internal noises in different channels were partially correlated when stimuli in those channels were presented simultaneously and were independent when the stimuli were presented successively. Cancellation of the correlated noise is therefore possible with simultaneous comparisons, making such discrimination better than that achievable with successive comparisons.
• Green, D. M., Berg, B. G., Dai, H., Eddins, D. A., Onsan, Z., & Nguyen, Q. (1992). Spectral shape discrimination of narrow-band sounds. Journal of the Acoustical Society of America, 92(5), 2586-2597.
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  PMID: 1479122;Abstract: Measurements are reported on the detectability of signals added to narrow- band sounds. The narrow-band sounds had a bandwidth of 20 Hz and were either Gaussian noise with flat amplitude spectra or sets of equal-amplitude sinusoidal components whose phases were chosen at random. Four different kinds of sinusoidal signals were used. Two signals produced symmetric changes in the audio spectrum adding a component either at the center of the spectrum or at both ends. The other two signals produced asymmetric changes adding a component at either end of the spectrum. The overall level of the sound was randomly varied on each presentation, so that the presence of a signal was largely unrelated to the absolute level of the signal component(s). A model is proposed that assumes the detection of the symmetric signals is based on changes in the shape of the power spectrum of the envelope. Such changes in the envelope power spectrum are probably heard as changes in the 'roughness' or 'smoothness' of the narrow-band sound. The predictions of this model were obtained from computer simulations. For the asymmetric signals, the most probable detection cues were changes in the pitch of the narrow-band sound. Results from a variety of different experiments using three listeners support these conjectures.
• Dai, H., & Buus, S. (1991). Effect of gating the masker on frequency-selective listening [1]. Journal of the Acoustical Society of America, 89(4 I), 1816-1818.
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  PMID: 2045588;
• Dai, H., & Green, D. M. (1991). Effect of amplitude modulation on profile detection. Journal of the Acoustical Society of America, 90(2 I), 836-845.
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  PMID: 1939888;Abstract: The effect of amplitude modulation on profile detection was examined in three experiments. The observer's task was to determine in which observation interval an increment was added to the 1000-Hz target component of a multitone complex in which the components were equally spaced on a logarithmic frequency scale from 200 to 5000 Hz. The target was unmodulated throughout the study. In some conditions, all nontarget components of the standard were modulated in phase; in other conditions, they were modulated with random phase. In experiment 1, the threshold was measured as a function of the modulation rate. The results show that, at low modulation rates, 5 Hz for example, modulation elevates threshold by about 13 dB. The threshold decreases as the modulation rate increases, with the threshold elevation being only 3 dB at 80 Hz. In experiment 2, threshold was measured as a function of modulation depth for both 21- and 5-component complexes. The results show that for a 5-Hz modulation rate the threshold decreases as the modulation depth decreases, and that the rate of decrease is greater for the 21-component complex than for the 5-component complex. In experiment 3, the effects of random-phase modulation were explored; the phase of the modulation waveform was randomly chosen for each component. The results show that there is no difference between in-phase and random-phase modulation when each component occupies a different critical band. If, however, two or more components occupy the same critical band, then randomizing the phase of modulation reduces the effective depth of modulation within that critical band, and the effect of modulation is thereby lessened.
• Dai, H., Scharf, B., & Buus, S. (1991). Effective attenuation of signals in noise under focused attention. Journal of the Acoustical Society of America, 89(6), 2837-2842.
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  PMID: 1918627;Abstract: When attending to a tone at a given frequency, listeners are most sensitive to that tone and others within a restricted band of frequencies surrounding it. This region of enhanced sensitivity defines the attention band that was measured in two experiments using a modified version of the probe-signal method of Greenberg and Larkin [J. Acoust. Soc. Am. 44, 1513-1523 (1968)]. Experiment 1 showed that at five center frequencies, from 0.25 to 4.0 kHz, the shape of the attention band resembles that of the auditory filter as inferred from notched-noise masking experiments by other investigators. The width of the attention band is close to the critical band at higher frequencies, but only half as wide at 0.25 and 0.5 kHz. Experiment 2 produced psychometric functions for unattended probe tones at least 0.23 kHz away from a fully attended, 1-kHz target tone. From these functions, the effective attenuation, measured as the threshold difference between the 1-kHz target and the probes, was estimated to be 7 dB; the amount of attenuation appeared to be about the same regardless of how far the probe frequency was from the attended band. One interpretation of these results is that bands centered on the unattended tones contribute to the decision process with some small but measurable weight and are not entirely ignored.
• Green, D. M., & Dai, H. (1991). Probability of being correct with 1 of M orthogonal signals. Perception & Psychophysics, 49(1), 100-101.
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  PMID: 2011448;
• Dai, H., & Feng, R. (1988). Anisotropy of ultrasonic speed in muscular tissues. Chinese Journal of Acoustics, 7(2), 171-175.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.
• Dai, H., & Feng, R. (1988). Ultrasonic attenuation in suspension of red cells. Ultrasonics, 26(1), 168-170.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.
• Dai, H., & Feng, R. (1986). Anisotropy of sound propagation in media with fibrous structure. Science Bulletin, 32(1), 665-666.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.
• Dai, H., & Feng, R. (1986). Ultrasonic attenuation in normal blood. Acta Biophysica, 2(1), 117-120.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.
• Feng, R., & Dai, H. (1985). The validity of the acoustical Kramers Kronig relationship for mammalian soft tissues. Acta Biophysica, 1(1), 15-20.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.
• Feng, R., Chen, Z., Zhu, Z., & Dai, H. (1985). Ultrasonic attenuation and speed in mammalian soft tissues in vitro.. Acta Acustica, 10(1), 285-292.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.
• Feng, R., Chen, Z., Zhu, Z., & Dai, H. (1983). A pulse-transmission technique for measuring ultrasonic properties of acoustical media. Acoustic Technique, 2(2), 28-31.
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  Abstract: A simplified model is used to work out the anisotropy of sound speed in a fiber bundle. It is explained qualitatively why the sound speed in the direction of fiber is greater than that in the direction perpendicular to the fiber. Then an estimation of the difference in speed is presented. The estimation is in agreement with the experimental data.

Proceedings Publications

• Wright, B. A., & Dai, H. (2013, June). Tuning in the time domain revealed through detection of auditory signals of unexpected duration or presentation time. In International Congress on Acoustics, 2013, 1-4.
• Dai, H. (2008, July). Feedback cancellation for hearing aids fitted to open ear canals. In ICALIP 2008 - 2008 International Conference on Audio, Language and Image Processing, Proceedings, 1606-1609.
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  Abstract: Fitting hearing aids to open ear canals, in spite of its many benefits and increased popularity, is particularly prone to feedback problems. The present study examined the system responses of the feedback path and how effective the feedback signals can be cancelled under the open-canal condition. Compared to a traditional fitting method with earmolds, the open-canal fitting has a smaller amount of usable gain due to a minimal sound attenuation (27 dB) in the open canal. Furthermore, the open-canal fitting appears to have no advantage over the traditional method in the amount of extra usable gain (15 dB) that the current feedback-cancellation system provides. Significant improvement to the feedback-cancellation system, either from increased signal-processing power or from the improvement in design based on the knowledge of the open-canal characteristics, will be needed to extend the benefits of the open-canal fitting method to patients with more than a moderate hearing loss. © 2008 IEEE.
• Dai, H. (1998, June). Decision weights for pitch perception. In 16th International Congress on Acoustics 1998, 16, 1-4.
• Dai, H., & Feng, R. (1985, April). Anisotropy of sound propagation in media with fibrous structure. In WESTPAC II Acoustics Conference, 85, 212-214.
• Feng, R., & Dai, H. (1985, April). The validity of the acoustical Kramers-Kronig relationship for mammalian soft tissues.. In WESTPAC II Acoustics Conference, 85, 220-224.

Presentations

• Buss, E., & Dai, H. (2017, Spring). Effects of temporal coherence and signal-frequency uncertainty for tone detection in a random-frequency multi-tonal masker. Journal of the Acoustical Society of America.
• Dai, H. (2017, October). Hearing research keynote speaker. 3rd Chinese Conference of Hearing Research. Nanjing, China.
• Mast, W., & Dai, H. (2017, March). In search of an improved pure-tone audiometry procedure. Conference of the American Auditory Society. Scotsdale, AZ: American Auditory Society.
• Dai, H., & Hess, S. (2016, March). On Estimating Internal Noise: Comparison of Three Methods. Conference of the American Auditory Society. Scotsdale, AZ: American Auditory Society.
• Hess, S., & Dai, H. (2016, March). Statistical Confidence in the Comparison between Estimated Decision Weights. Conference of the American Auditory Society. Scotsdale, AZ: American Auditory Society.
• Hess, S., & Dai, H. (2015, March). Inter-Pixel Correlation of Estimated Decision Weights. Conference of the American Auditory Society. Scotsdale, AZ: American Auditory Society.
• Dai, H. (2014, January). Global versus local processing in auditory pattern perception. 8th Conference of Auditory Cognitive Neuroscience Society. Univ of Arizona, Tucson, AZ: Auditory Cognitive Neuroscience Society.
• Dai, H. (2014, May). Seeing the wood for the trees: Delineating global (holistic) and local (analytic) processing in the perception of sound spectral patterns. Third International Conference on Psychology and Social Harmony. Su Zhou, China.
• Dai, H., Buss, E., & Wright, B. (2014, March). On estimating detection and discrimination thresholds. Conference of the American Auditory Society. Scotsdale, AZ: American Auditory Society.

Poster Presentations

• Dai, H., & Hess, S. (2015, December). On estimating internal noise. ARIZONA COGNITIVE SCIENCE CONCLAVE 2015. Univ of Arizona, Tucson, AZ: Sponsored by the Cognitive Science Program and the College of Social and Behavioral Sciences, University of Arizona.
• Dai, H. (2014, April). Delineating synthetic from analytic listening in pitch perception. 2014 Poster Session of the School of Mind, Brain, and Behavior. Student Union, Univ of Arizona, Tucson, AZ: The School of Mind, Brain, and Behavior, College of Science, Univ of Arizona.
• Dai, H. (2014, April). Effect of aging on frequency discrimination. 2014 Poster Session of the School of Mind, Brain, and Behavior. Student Union, Univ of Arizona, Tucson, AZ: The School of Mind, Brain, and Behavior, College of Science, Univ of Arizona.
• Dai, H., Buss, E., & Primus, M. (2014, February). Psychometric Functions for Pure-tone Frequency Discrimination by Aged Listeners. annual conference of the Association for Research in Otolaryngology. San Diego, CA: Association for Research in Otolaryngology.