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W A Yost

Publications and source records attributed to W A Yost.

At least 37 records · Page 2Linked to original sources
PubMed1992

Behavioral measures of frequency selectivity in the chinchilla.

A simultaneous masking procedure was used to derive four measures of frequency selectivity in the chinchilla. The first experiment measured critical masking ratios (CRs) at various signal frequencies. Estimates of the chinchillas' critical bandwidths derived from the CRs were much broader than comparable human estimates, indicating that the chinchilla may have inferior frequency selectivity. The second experiment measured critical bandwidths at 1, 2, and 4 kHz in a band-narrowing experiment. This technique yielded narrower estimates of critical bandwidth; however, chinchillas continued to exhibit poor frequency selectivity compared to man. The third experiment measured auditory-filter shape at 0.5, 1, and 2 kHz via rippled noise masking. Results of the rippled noise masking experiment indicate that auditory filters of humans and chinchillas are similar in terms of shape and bandwidth with chinchillas showing only slightly poorer frequency selectivity. The final experiment measured auditory filter shape at 0.5, 1, 2, and 4 kHz using notched noise masking. This experiment yielded auditory filter shapes and bandwidths similar to those derived from man. The discrepancy between the indirect estimates of frequency selectivity derived from CR and band-narrowing techniques and the direct estimates derived from rippled noise and notched noise masking are explained by taking into account the processing efficiency of the subjects.

Acoustics↗
PubMed1991

Auditory image perception and analysis: the basis for hearing.

The premise of this paper is that the auditory system's primary function is its ability to determine the sources of sound. Auditory image perception and analysis are defined as the basis for sound source determination. Few studies in the literature have focused on understanding these abilities and the paper argues that more attention should be paid to auditory image perception and analysis. Four questions are posed for understanding auditory image formation and seven physical variables are described which might be used for auditory image perception. The paper relates auditory image perception and analysis to a number of other topics in the hearing sciences in order to reinforce the argument that auditory image perception and analysis are the basis of hearing.

Acoustic Stimulation↗
PubMed1991

Thresholds for segregating a narrow-band from a broadband noise based on interaural phase and level differences.

Either an interaural phase shift or level difference was introduced to a narrow section of broadband noise in order to measure the acuity of the binaural system to segregate a narrowband from a broadband stimulus. Listeners were asked to indicate whether this dichotic noise or a totally diotic noise was presented in a single-interval procedure. Thresholds for interaural phase and level differences were estimated from four point psychometric functions. These thresholds were determined for three bandwidths of interaurally altered noise (2, 10, and 100 Hz) centered at four center frequencies (200, 500, 1000, and 1600 Hz). Thresholds were lowest when the interaurally altered band of noise was centered at 500 Hz, and thresholds increased as the bandwidth of the interaurally altered noise decreased. Performance did not exceed 75% correct when either an interaural phase shift (180 degrees) or interaural level difference (50 dB) was introduced to a 100 Hz band of noise centered at frequencies higher than 1600 Hz. In a second set of conditions, performance was measured when both an interaural phase shift and level difference were presented in a 10-Hz-wide band of noise centered at 500 Hz. A version of the Durlach E-C model was able to account for a great deal of the data. The results are discussed in terms of the Huggins dichotic pitch.

Attention↗
PubMed1990

A comparison among three measures of cross-spectral processing of amplitude modulation with tonal signals.

Results were obtained from three paradigms used to study cross-spectral processing of envelope modulation [comodulation masking release (CMR), comodulation detection difference (CDD), and modulation detection interference (MDI)]. When tonal carriers separated by two octaves (flanking tone at 1000 Hz and target tone at 4000 Hz) were amplitude modulated at 20 Hz, there was no evidence of a cMR or CDD effect, but there was substantial MDI.

Acoustic Stimulation↗
PubMed1990

Temporal integration in amplitude modulation detection.

Thresholds for detecting sinusoidal amplitude modulation (AM) of a wideband noise carrier were measured as a function of the duration of the modulating signal. The carrier was either; (a) gated with a duration that exceeded the duration of modulation by the combined stimulus rise and fall times; (b) presented with a fixed duration that included a 500-ms carrier fringe preceding the onset of modulation; or (c) on continuously. In condition (a), the gated-carrier temporal modulation transfer functions (TMTFs) exhibited a bandpass characteristic. For AM frequencies above the individual subject's TMTF high-pass segment, the mean slope of the integration functions was - 7.46 dB per log unit duration. For the fringe and continuous-carrier conditions [(b) and (c)], the mean slopes of the integration functions were, respectively, - 9.30 and - 9.36 dB per log unit duration. Simulations based on integration of the output of an envelope detector approximate the results from the gated-carrier conditions. The more rapid rates of integration obtained in the fringe and continuous-carrier conditions may be due to "overintegration" where, at brief modulation durations, portions of the unmodulated carrier envelope are included in the integration of modulating signal energy.

Adult↗
PubMed1989

Across-critical-band processing of amplitude-modulated tones.

Two experiments using two-tone sinusoidally amplitude-modulated stimuli were conducted to assess cross-channel effects in processing low-frequency amplitude modulation. In experiment I, listeners were asked to discriminate between two sets of two-tone amplitude-modulated complexes. In one set, the modulation phase of the lower frequency carrier tone was different from that of the upper frequency carrier tone. In the other stimulus set, both amplitude-modulated carriers had the same modulator phase. The amount of phase shift required to discriminate between the two stimulus sets was determined as a function of the separation between the two carriers, modulation depth, and modulation frequency. Listeners could discriminate a 50 degrees-60 degrees phase shift between the modulated envelopes for tones separated by more than a critical band. In experiment II, the modulation depth required to detect modulation of a probe carrier was measured in the presence of an amplitude-modulated masker. The threshold for detecting probe modulation was determined as a function of the separation between the masker and probe carriers, the phase difference between the masker and probe modulators, and masker modulation depth (in all conditions, the rate of probe and masker modulation was 10 Hz). The threshold for detecting probe modulation was raised substantially when the masker tone was also modulated. The results are consistent with theories suggesting that amplitude modulation helps form auditory objects from complex sound fields.

Auditory Perception↗
PubMed1989

Modulation interference in detection and discrimination of amplitude modulation.

Two experiments were conducted to assess the effect of the rate of sinusoidal amplitude modulation (SAM) of a masker tone on detection of SAM of a probe tone (experiment 1) or on SAM-rate discrimination for the probe tone (experiment 2). When modulated at the same rate as the probe, the masker interfered with both the detection of probe modulation and the discrimination of the rate of probe modulation. The interference was obtained when the masker was either higher or lower in frequency than the probe (the probe and masker were separated by 2 oct). The amount of interference in detecting probe modulation (experiment 1) decreased as the common base rate of modulation was increased from 5 to 200 Hz. For rate discrimination (experiment 2), the amount of interference remained approximately the same for base rates of 2-40 Hz, the range over which rate discrimination was measured. In both experiments, the amount of interference was reduced when the masker was modulated at a different rate than the probe.

Acoustic Stimulation↗
PubMed1988

The masking-level difference and overall masker level: restating the internal noise hypothesis.

Recent investigations of the masking-level difference (MLD) have often involved measurement of the MLD as a function of masker level. The results show, as had earlier work, that the size of the MLD decreases as the masker level decreases. These studies have usually not considered an earlier explanation of the dependency of the MLD on masker level, that is, that additive internal noise, which is partially interaurally uncorrelated, leads to decorrelated maskers at low levels of the external masking noise. Because maskers that are decorrelated yield small MLDs, the MLD is likewise small at low masker levels. This review article shows that this explanation provides a good fit to data obtained over the past four decades. It also shows that the MLD depends less on masker level with insert phones than with supraaural phones as would be predicted by the additive internal noise explanation and the observation of lower internal noise with the use of insert phones. It is concluded that the internal noise explanation should be considered when the MLD is measured as a function of masker level.

Humans↗
PubMed1988

Discrimination of interaural differences of level as a function of frequency.

Discrimination of interaural differences of level (IDLs) was measured for pure tones as a function of frequency and as a function of the interaural difference of phase or level of a standard. Varying the interaural difference of the standard was assumed to change the lateral position of its intracranial image. Threshold IDLs were approximately constant over a frequency range from 200-5000 Hz, except in a region near 1000 Hz where they were slightly elevated. Thresholds increased as the value of the standard interaural differences of phase or level increased, implying that interaural resolution declines as the lateral image moves away from midline. The results are generally consistent with the predictions of current models of lateralization, but additions to these models are required in order for them to account for the slight frequency dependence of threshold IDLs.

Auditory Perception↗
PubMed1987

Temporal changes in a complex spectral profile.

The spectral properties of a complex stimulus (rippled noise) were varied over time, and listeners were asked to discriminate between this stimulus and a flat-spectrum, stationary noise. The spacing between the spectral peaks of rippled noise was changed sinusoidally as a function of time, or the location of the spectral peaks of rippled noise was moved up and down the spectrum as a sinusoidal function of time. In most conditions, listeners were able to make the discriminations up to rates of temporal modulation of 5-10 cycles per second. Beyond 5-10 cps the rippled noise with the temporally varying peaks was indiscriminable from a flat (nonrippled) noise. The results suggest that for temporal changes in the spectral peaks of rippled noise, listeners cannot monitor the output of a single (or small number of) auditory channel(s) (critical bands), or that the mechanism used to extract the perceptual information from these stimuli is slow. Temporal variations in the spectral properties of rippled noise may relate to temporal changes in the repetition pitch of complex sounds, the temporal properties of the coloration added to sound in a reverberant environment, and the nature of spectral peak changes such as those that occur in speech-formant transitions. The results are relevant to the general issue of the auditory system's ability to extract information from a complex spectral profile.

Auditory Pathways↗
PubMed1986

Masking-level differences for trains of clicks.

Masking-level differences (MLDs) were measured for trains of 2000-Hz bandpass clicks as a function of the interclick interval (ICI) and the number of clicks in the train. The magnitude of the MLD grew as the number of clicks in the train was increased from 1 to 32. While the MLDs tended to be larger at longer ICIs, the effect was mediated by changes in detectability in the homophasic conditions. For click trains consisting of 4-32 clicks, the improvement in detectability in the antiphasic conditions with increases in the number of clicks appears to be the result of integration of acoustic power, as is the case for the homophasic conditions. The absence of MLDs for short trains of high-frequency transients remains quite puzzling, since large MLDs are found with single, low-frequency transients.

Auditory Threshold↗
PubMed1985

Prior stimulation and the masking-level difference.

Signal detection in diotic (NoSo) and dichotic (NoS pi) conditions was measured as a function of the stimulus parameters of the noise that preceded the signal-plus-masker. When the signal and masker were both pulsed, dichotic signal detection was worse than when the masker was continuous or when the onset of the masker preceded the signal-plus-masker by at least 500 ms. The dichotic detection thresholds decreased as the duration of the pulsed signal plus pulsed masker was increased. The level, spectrum, interaural configuration, duration, and temporal proximity of the prior noise (forward fringe) relative to the masker and/or signal and masker were all investigated. Almost any difference between the parameters of the fringe and the masker resulted in poorer signal detection in the dichotic conditions. These same stimulus conditions produced small (less than 2.2 dB) changes in the diotic detection thresholds. The various models of the Masking-Level Difference (MLD) may be modified to qualitatively describe some of these results.

Acoustic Stimulation↗
PubMed1984

The precedence effect: revisited.

The precedence effect, as investigated by Wallach et al. [Am. J. Psychol. 62, 324-336 (1949)] was studied in three experiments. Experiment I was a replication of the original work of Wallach et al. Although the first click pair appears to dominate the perception of the position of the lateral image, the effect of the first click pair does not appear to "offset" or "cancel" the effect of the second click pair in terms of producing a lateral image at midline. The data are consistent with Zurek's [J. Acoust. Soc. Am. 67, 952-964 (1980)] proposal that the binaural system is less sensitive to the interaural temporal difference of the second click pair. Experiment II indicated that the effect of the first click pair on lateral judgments still dominates that of the second click pair when the images are judged to be off midline. In all of these studies, the variability of the data is quite high. Experiment III showed that the first click pair also led to a larger change in masked thresholds (masking-level differences, MLDs) than does the second click pair. These data reconfirm the use of two-click stimuli for demonstrations of the precedence effect and they describe some of the limitations of the procedure and the generalities of the effect.

Acoustic Stimulation↗
PubMed1983

Psychophysics and neurophysiology of repetition noise processing in a vertebrate auditory system.

The psychophysics and neurophysiology of repetition noise (RN) processing was studied in the goldfish. RN is the sum of a noise waveform with its delayed (by T s) repetition, which may be attenuated (by A dB), and inverted relative to the undelayed signal. Such a signal has a periodic spectrum with peaks separated by 1/T Hz, and a prominence in its autocorrelation function at T s. In usual environments, RN contains information about sound-reflecting surfaces. Delays in the range of 0.5-20 ms create pitch sensations in man. Psychophysical experiments using classical respiratory conditioning investigated the masking effectiveness of RN on tones, the detection of changes in delay (T) at various values of T, A and overall noise level, and the values of A required to bring a 20% delay discrimination to threshold. While the masking data define detection filters quite broadly tuned compared with man, various measures of delay discrimination are comparable to those for man. Unit responses from the auditory nerve are consistent with broadly tuned psychophysical filters, but in all cells studied show prominent inter-spike-interval (ISI) peaks which predict the delay values used to generate the RN. We conclude that the qualitative features of RN are coded in ISIs, and are processed by the CNS in the time domain. Similar mechanisms may be used by other vertebrate species in processing repetition noise.

Animals↗
PubMed1982

The phase angle of addition in temporal masking for diotic and dichotic listening conditions.

The phase angle, alpha, between a tonal signal and a tonal masker was varied from 0 degrees to 135 degrees in simultaneous masking, forward masking, and pulsation-threshold paradigms. In all conditions the frequency of the signal and masker was 500 Hz. For forward masking both diotic (MOSO) and dichotic (MOS pi) listening conditions were investigated. Only the dichotic case was studied using the pulsation threshold method. In simultaneous masking, thresholds varied as a function of alpha in both diotic and dichotic conditions. Thresholds in the diotic conditions were consistently different from those in the dichotic conditions -- i.e., there were masking-level differences (MLDs) at most values of alpha tested. In forward masking and pulsation-threshold, however, thresholds were independent of alpha in the dichotic conditions; and thresholds were independent of alpha in the diotic, forward masking conditions. Nevertheless, for forward masking the dichotic thresholds remained below the diotic thresholds, yielding MLDs of 3-6 dB. Thus, in nonsimultaneous masking, there is a clear effect of the interaural signal phase, but not of the masker-signal phase relationship, on signal detectability. These results imply that masker-signal phase information is either not preserved or not used by subjects in nonsimultaneous tone-on-tone masking experiments.

Auditory Perception↗
PubMed1982

Measures of intensity discrimination.

Several different measures have been employed in the literature to describe performance by human observers in intensity discrimination tasks. These measures include the difference limen (DL) or "delta I in dB," the Weber fraction (delta I/I), and signal-to-masker ratio (Ps/Pm). This article describes the mathematical relationship among these measures for conditions in which masker and signal are (1) sinusoids of the same frequency; (2) sinusoids of different frequencies; and (3) noise waveforms. We provide a table which contains values of each of these measures, describing equivalent performance over the typical range obtained in most intensity discrimination experiments. We express some cautions that should be observed in choosing and reporting particular measures of intensity discrimination.

Humans↗
PubMed1982

The dominance region and ripple noise pitch: a test of the peripheral weighting model.

An estimate of the spatial curve of pitch dominance for the repetition pitch of ripple noise was measured using the pitch strength discrimination procedure. A variety of stimulus conditions were examined. The peripheral weighting model [Yost and Hill, J. Acoust. Soc. Am. 66, 400-410 (1979)] of repetition pitch assumes a relationship between the curve of pitch dominance and the shape of the psychophysical suppression of unmasking function. Ripple noise was also used to estimate the psychophysical suppression or unmasking function. The results indicate that with the estimates of the psychophysical suppression or unmasking function the peripheral weighting model can account for the general shape of the curve of pitch dominance.

Auditory Threshold↗