Brian Moore
University of Cambridge, Psychology, Emeritus
These experiments measure the ability to detect a change in the relative phase of a single component in a harmonic complex tone. Complex tones containing the first 20 harmonics of 50, 100, or 200 Hz, all at equal amplitude, were used. All... more
These experiments measure the ability to detect a change in the relative phase of a single component in a harmonic complex tone. Complex tones containing the first 20 harmonics of 50, 100, or 200 Hz, all at equal amplitude, were used. All of the harmonics except one started in cosine phase. The remaining harmonic started in cosine phase, but was shifted in phase half-way through either the first or the second of the two stimuli comprising a trial. The subject had to identify the stimulus containing the phase-shifted component. For normally hearing subjects tested at a level of 70 dB SPL per component, thresholds for detecting the phase shift [i.e., phase difference limens (DLs)] were smallest (2 degrees-4 degrees) for harmonics above the eighth and for the lowest fundamental frequency (F0). Changes in phase were not detectable for harmonic numbers below three or four at the lowest F0 and below 5-13 at the highest F0. The DLs increased slightly for the highest harmonics in the complexes. The DLs increased markedly with decreasing level, except for the highest harmonic, where only a small effect of level was found. Subjects reported that the phase-shifted harmonic appeared to "pop out" and was heard with a pure-tone quality. A pitch-matching experiment demonstrated that the pitch of this tone corresponded to the frequency of the phase-shifted component. For the highest harmonic, the phase shift was associated with a downward shift of the edge pitch heard in the reference (all cosine phase) stimulus. When the phases of the components in the reference stimulus were randomized, phase DLs were much higher (and often impossible to measure), the pop-out phenomenon was not observed, and no edge pitch was heard. Subjects with unilateral cochlear hearing impairment generally showed poorer phase sensitivity in their impaired than in their normal ears, when the two ears were compared at equal sound-pressure levels. However, at comparable sensation levels, the impaired ears sometimes showed lower phase DLs. The results are explained by considering the waveforms that would occur at the outputs of the auditory filters in response to these stimuli.
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This article examines the idea that the temporal resolution of the auditory system can be modeled using a temporal window (an intensity weighting function) analogous to the auditory filter measured in the frequency domain. To estimate the... more
This article examines the idea that the temporal resolution of the auditory system can be modeled using a temporal window (an intensity weighting function) analogous to the auditory filter measured in the frequency domain. To estimate the shape of the hypothetical temporal window, threshold was measured for a brief sinusoidal signal presented in a temporal gap between two bursts of noise. The duration of the gap was systematically varied and the signal was placed both symmetrically and asymmetrically within the gap. The data were analyzed by assuming that the temporal window had the form of a simple mathematical expression with a small number of free parameters. The values of the parameters were adjusted to give the best fit to the data. The analysis assumed that, for each condition, the temporal window was centered at the time giving the highest signal-to-masker ratio, and that threshold corresponded to a fixed ratio of signal energy to masker energy at the output of the window. The data were fitted well by modeling each side of the window as the sum of two rounded-exponential functions. The window was highly asymmetric, having a shallower slope for times before the center than for times after. The equivalent rectangular duration (ERD) of the window was typically about 8 ms. The ERD increased slightly when the masker level was decreased, but did not differ significantly for signal frequencies of 500 and 2000 Hz. The temporal-window model successfully accounts for the data from a variety of experiments measuring temporal resolution. However, it fails to predict certain aspects of forward masking and of the detection of amplitude modulation at high rates.
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Threshold was measured for a 20-ms, 1-kHz sinusoidal signal following a narrow-band noise masker centered at 1 kHz with an overall level of 70 dB SPL. The effect of temporal uncertainty was investigated by providing a broadband, low-level... more
Threshold was measured for a 20-ms, 1-kHz sinusoidal signal following a narrow-band noise masker centered at 1 kHz with an overall level of 70 dB SPL. The effect of temporal uncertainty was investigated by providing a broadband, low-level noise cue, gated synchronously either with the masker intervals or the signal intervals. The cue could be either in the same ear as the signal-plus-masker, or in the opposite ear. In every case the cue produced a reduction in signal threshold, the largest reduction (about 20 dB) occurring when the cue was gated with the masker. The results indicate that in specific conditions, when the signal is similar in quality to the masker (having a similar center frequency and bandwidth), forward masking can involve a high degree os temporal uncertainty. Effects resembling "suppression" can be produced by providing a temporal cue. Adding a 1.2-kHz sinusoid at 90 dB SPL to the masker produced a 10-dB larger reduction in threshold than the noise cue. This greater effect is probably attributable to suppression of the masker by the sinusoid.
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The loudness model described by Moore et al. [J. Audio Eng. Soc. 45, 224-240 (1997)] forms the basis for a recent ANSI standard for the calculation of the loudness of steady sounds. However, the model does not give accurate predictions of... more
The loudness model described by Moore et al. [J. Audio Eng. Soc. 45, 224-240 (1997)] forms the basis for a recent ANSI standard for the calculation of the loudness of steady sounds. However, the model does not give accurate predictions of the absolute thresholds published in a recent ISO standard. Here it is described how the assumed middle-ear transfer function in the model can be modified to give more accurate absolute threshold predictions. The modified model also gives reasonably accurate predictions of the equal-loudness contours published in a recent ISO standard.
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Bernstein and Oxenham [(2008). J. Acoust. Soc. Am. 124, 1653-1667] measured thresholds for discriminating the fundamental frequency, F0, of a complex tone that was passed through a fixed bandpass filter. They found that performance... more
Bernstein and Oxenham [(2008). J. Acoust. Soc. Am. 124, 1653-1667] measured thresholds for discriminating the fundamental frequency, F0, of a complex tone that was passed through a fixed bandpass filter. They found that performance worsened when the F0 was decreased so that only harmonics above the tenth were audible. However, performance in this case was improved by mistuning the odd harmonics by 3%. Bernstein and Oxenham considered whether the results could be explained in terms of temporal fine structure information available at the output of a single auditory filter and concluded that their results did not appear to be consistent with such an explanation. Here, it is argued that such cues could have led to the improvement in performance produced by mistuning the odd harmonics.
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For normal listeners, intensity DLs for Gaussian‐shaped tone pulses are largest at medium pulse durations when the pedestals are 10 dB above threshold, either in quiet or in a pink‐noise background. One explanation is that worst... more
For normal listeners, intensity DLs for Gaussian‐shaped tone pulses are largest at medium pulse durations when the pedestals are 10 dB above threshold, either in quiet or in a pink‐noise background. One explanation is that worst performance occurs when the internal representation is most compact in time and frequency, affording minimal opportunity for multiple looks [N. H. van Schijndel, T. Houtgast, and J. Festen, J. Acoust. Soc. Am. 105, 3425–3435 (1999)]. However, the mid‐duration worsening is largest for medium overall levels, suggesting an involvement of the compression on the basilar membrane (BM), which is also greatest at medium levels [T. Baer, B. C. J. Moore, and B. R. Glasberg, J. Acoust. Soc. Am. 106, 1907–1916 (1999)]. If so, the mid‐duration worsening should be reduced when BM compression is reduced by outer hair cell damage. To test this, subjects with sensorineural losses were tested using 1‐kHz or 4‐kHz pulses, in quiet or in pink noise that raised thresholds by 10–20 dB. For subjects with mild losses, poorest performance was sometimes found for medium durations. For more severe losses, intensity DLs tended to improve monotonically or remain roughly constant with increasing duration. The results provide support for both multiple‐look and BM‐compression explanations. [Work supported by MRC.]
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Temporal modulation transfer functions were obtained using sinusoidal carriers for four normally hearing subjects and three subjects with mild to moderate cochlear hearing loss. Carrier frequencies were 1000, 2000 and 5000 Hz, and... more
Temporal modulation transfer functions were obtained using sinusoidal carriers for four normally hearing subjects and three subjects with mild to moderate cochlear hearing loss. Carrier frequencies were 1000, 2000 and 5000 Hz, and modulation frequencies ranged from 10 to 640 Hz in one-octave steps. The normally hearing subjects were tested using levels of 30 and 80 dB SPL. For the higher level, modulation detection thresholds varied only slightly with modulation frequency for frequencies up to 80 Hz, but decreased for high modulation frequencies. The decrease can be attributed to the detection of spectral sidebands. For the lower level, thresholds varied little with modulation frequency for all three carrier frequencies. The absence of a decrease in the threshold for large modulation frequencies can be explained by the low sensation level of the spectral sidebands. The hearing-impaired subjects were tested at 80 dB SPL, except for two cases where the absolute threshold at the carrier frequency was greater than 70 dB SPL; in these cases a level of 90 dB was used. The results were consistent with the idea that spectral sidebands were less detectable for the hearing-impaired than for the normally hearing subjects. For the two lower carrier frequencies, there were no large decreases in threshold with increasing modulation frequency, and where decreases did occur, this happened only between 320 and 640 Hz. For the 5000-Hz carrier, thresholds were roughly constant for modulation frequencies from 10 to 80 or 160 Hz, and then increased monotonically, becoming unmeasurable at 640 Hz. The results for this carrier may reflect "pure" effects of temporal resolution, without any influence from the detection of spectral sidebands. The results suggest that temporal resolution for deterministic stimuli is similar for normally hearing and hearing-impaired listeners.
Research Interests: Physics, Acoustics, Psychoacoustics, Medicine, Multidisciplinary, and 15 moreHumans, Presbycusis, Female, Male, Aged, Middle Aged, Adult, Modulation Transfer Function, Hearing Impaired, Auditory Threshold, Frequency Modulation, Amplitude Modulation, Carrier Signal, Pitch discrimination, and normal hearing
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Research Interests: Computer Science, Acoustics, Auditory Perception, Audiology, Psychoacoustics, and 14 moreTime Perception, Medicine, Learning, TIME, Software, Computers, Humans, Clinical Sciences, Fine Structure Constant, Auditory Threshold, Time, Task Performance and Analysis, Acoustic Stimulation, and Neuropsychological Tests
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Gockel, Carlyon, and Plack [J. Acoust. Soc. Am. 116, 1092-1104 (2004)] showed that discrimination of the fundamental frequency (F0) of a target tone containing only unresolved harmonics was impaired when an interfering complex tone with... more
Gockel, Carlyon, and Plack [J. Acoust. Soc. Am. 116, 1092-1104 (2004)] showed that discrimination of the fundamental frequency (F0) of a target tone containing only unresolved harmonics was impaired when an interfering complex tone with fixed F0 was added to the target, but filtered into a lower frequency region. This pitch discrimination interference (PDI) was greater when the interferer contained resolved harmonics than when it contained only unresolved harmonics. Here, it is examined whether this occurred because, when the interferer contained unresolved harmonics, "pitch pulse asynchrony (PPA)" between the target and interferer provided a cue that enhanced performance; this was possible in the earlier experiment because both target and interferer had components added in sine phase. In experiment 1, it was shown that subjects were moderately sensitive to the direction of PPA across frequency regions. In experiments 2 and 3, PPA cues were eliminated by adding the components of the target only, or of both target and interferer, in random phase. For both experiments, an interferer containing resolved harmonics produced more PDI than an interferer containing unresolved harmonics. These results show that PDI is smaller for an interferer with unresolved harmonics even when cues related to PPA are eliminated.
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The effect of level and frequency on the audibility of partials was measured for complex tones with partials uniformly spaced on an equivalent rectangular bandwidth (ERB(N)) number scale. On each trial, subjects heard a sinusoidal... more
The effect of level and frequency on the audibility of partials was measured for complex tones with partials uniformly spaced on an equivalent rectangular bandwidth (ERB(N)) number scale. On each trial, subjects heard a sinusoidal "probe" followed by a complex tone. The probe was mistuned downwards or upwards (at random) by 4.5% from the frequency of one randomly selected partial in the complex. The subject indicated whether the probe was higher or lower in frequency than the nearest partial in the complex. The frequencies were roved from trial to trial, keeping frequency ratios fixed. In experiment 1, the level per partial, L, was 40 or 70 dB SPL and the mean frequency of the central partial, f(c), was 1201 Hz. Scores for the highest and lowest partials in the complexes were generally high for all spacings. Scores for the inner partials were close to chance at 0.75-ERB(N) spacing, and improved as the spacing was increased up to 2 ERB(N). For intermediate spacings, performance was better for the lower level used. In experiment 2, L was 70 dB SPL and f(c) was 3544 Hz. Performance worsened markedly for partial frequencies above 3544 Hz, consistent with a role of phase locking.
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This study examined whether "modulation masking" could be produced by temporal similarity of the probe and masker envelopes, even when the masker envelope did not contain a spectral component close to the probe... more
This study examined whether "modulation masking" could be produced by temporal similarity of the probe and masker envelopes, even when the masker envelope did not contain a spectral component close to the probe frequency. Both masker and probe amplitude modulation were applied to a single 4-kHz sinusoidal or narrow-band noise carrier with a level of 70 dB SPL. The threshold for detecting 5-Hz probe modulation was affected by the presence of a pair of masker modulators beating at a 5-Hz rate (40 and 45 Hz, 50 and 55 Hz, or 60 and 65 Hz). The threshold was dependent on the phase of the probe modulation relative to the beat cycle of the masker modulators; the threshold elevation was greatest (12-15 dB for the sinusoidal carrier and 9-11 dB for the noise carrier, expressed as 20 log m) when the peak amplitude of the probe modulation coincided with a peak in the beat cycle. The maximum threshold elevation of the 5-Hz probe produced by the beating masker modulators was 7-12 dB greater than that produced by the individual components of the masker modulators. The threshold elevation produced by the beating masker modulators was 2-10 dB greater for 5-Hz probe modulation than for 3- or 7-Hz probe modulation. These results cannot be explained in terms of the spectra of the envelopes of the stimuli, as the beating masker modulators did not produce a 5-Hz component in the spectra of the envelopes. The threshold for detecting 5-Hz probe modulation in the presence of 5-Hz masker modulation varied with the relative phase of the probe and masker modulation. The pattern of results was similar to that found with the beating two-component modulators, except that thresholds were highest when the masker and probe were 180 degrees out of phase. The results are consistent with the idea that nonlinearities within the auditory system introduce distortion in the internal representation of the envelopes of the stimuli. In the case of two-component beating modulators, a weak component is introduced at the beat rate, and it has an amplitude minimum when the beat cycle is at its maximum. The results could be fitted well using two models, one based on the concept of a sliding temporal integrator and one based on the concept of a modulation filter bank.
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The dominant region for pitch was measured for complex tones with low fundamental frequency (F0=35 and 50 Hz). The tones contained 59 harmonics, added in cosine or random phase. The harmonics were split into two groups; group A containing... more
The dominant region for pitch was measured for complex tones with low fundamental frequency (F0=35 and 50 Hz). The tones contained 59 harmonics, added in cosine or random phase. The harmonics were split into two groups; group A containing harmonics 1‐K and group B containing harmonics (K+1)‐N. On each trial, two successive complex tones were presented. In one, the harmonics in group A were shifted down by deltaF0 and the harmonics in group B were shifted up by deltaF0. In the other tone, the shifts were in the opposite direction. The tones were presented in random order and the subject had to indicate which had the higher pitch. The pitch judgements followed the components in group B for small K and the components in group A for large K. The frequency corresponding to the middle of the transition region was taken as the center of the dominant region, fdom. The value of fdom varied markedly across subjects but typically corresponded to harmonic numbers above the 6th, for both phase conditions. Thus, the dominant harmonics were unresolved. These results indicate that resolution of individual harmonics is not the key factor determining the location of the dominant region. [Work supported by the MRC.]
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When a low harmonic in a harmonic complex tone is mistuned from its harmonic value by a sufficient amount it is heard as a separate tone, standing out from the complex as a whole. This experiment estimated the degree of mistuning required... more
When a low harmonic in a harmonic complex tone is mistuned from its harmonic value by a sufficient amount it is heard as a separate tone, standing out from the complex as a whole. This experiment estimated the degree of mistuning required for this phenomenon to occur, for complex tones with 10 or 12 equal-amplitude components (60 dB SPL per component). On each trial the subject was presented with a complex tone which either had all its partials at harmonic frequencies or had one partial mistuned from its harmonic frequency. The subject had to indicate whether he heard a single complex tone with one pitch or a complex tone plus a pure tone which did not "belong" to the complex. An adaptive procedure was used to track the degree of mistuning required to achieve a d' value of 1. Threshold was determined for each ot the first six harmonics of each complex tone. In one set of conditions stimulus duration was held constant at 410 ms, and the fundamental frequency was either 100, 200, or 400 Hz. For most conditions the thresholds fell between 1% and 3% of the harmonic frequency, depending on the subject. However, thresholds tended to be greater for the first two harmonics of the 100-Hz fundamental and, for some subjects, thresholds increased for the fifth and sixth harmonics. In a second set of conditions fundamental frequency was held constant at 200 Hz, and the duration was either 50, 110, 410, or 1610 ms. Thresholds increased by a factor of 3-5 as duration was decreased from 1610 ms to 50 ms. The results are discussed in terms of a hypothetical harmonic sieve and mechanisms for the formation of perceptual streams.
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... Brian CJ Moore, Deborah A. Vickers, Christopher J. Plack, Andrew J. Oxenham. Abstract. ... The measures of loudness recruitment were used to derive a parameter HL, the amount of the hearing loss attributable to OHC damage [BCJ Moore... more
... Brian CJ Moore, Deborah A. Vickers, Christopher J. Plack, Andrew J. Oxenham. Abstract. ... The measures of loudness recruitment were used to derive a parameter HL, the amount of the hearing loss attributable to OHC damage [BCJ Moore and BR Glasberg, Auditory Neurosci. ...
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These experiments on across-channel masking (ACM) and comodulation masking release (CMR) were designed to extend the work of Grose and Hall [J. Acoust. Soc. Am. 85, 1276-1284 (1989)] on CMR. They investigated the effect of the temporal... more
These experiments on across-channel masking (ACM) and comodulation masking release (CMR) were designed to extend the work of Grose and Hall [J. Acoust. Soc. Am. 85, 1276-1284 (1989)] on CMR. They investigated the effect of the temporal position of a brief 700-Hz signal relative to the modulation cycle of a 700-Hz masker 100% sinusoidally amplitude modulated (SAM) at a 10-Hz rate, which was either presented alone (reference masker) or formed part of a masker consisting of the 3rd to 11th harmonics of a 100-Hz fundamental. In the harmonic maskers, each harmonic was either SAM with the same 10-Hz modulator phase (comodulated masker) or with a shift in modulator phase of 90 degrees for each successive harmonic (phase-incoherent masker). When the signal was presented at the dips of the envelope of the 700-Hz component, the comodulated masker gave lower thresholds than the reference masker, while the phase-incoherent masker gave higher thresholds, i.e., a CMR was observed. No CMR was found when the signal was presented at the peaks of the envelope. In experiment 1, we replicated the experiment of Grose and Hall, but with an additional condition in which the 600- and 800-Hz components were removed from the masker, in order to investigate the role of within-channel masking effects. The results were similar to those of Grose and Hall. In experiment 2, the signal was added at the peaks of the envelope of the 700-Hz component, but in antiphase to the carrier of that component and at a level chosen to transform the peaks into dips. No CMR was found. Rather, performance was worse for both the comodulated and phase-incoherent maskers than for the reference masker. This was true even when the flanking components in the maskers were all remote in frequency from 700 Hz. In experiment 3, the masker components were all 50% SAM and the signal was added in antiphase at a dip of the envelope of the 700-Hz component, thus making the dip deeper. Performance was worse for the phase-incoherent than for the reference masker and was worse still for the comodulated masker. The results of all three experiments indicate strong ACM effects. CMR was found only when the signal was placed in the dips of the masker envelope and when it produced an increase in level relative to that in adjacent bands.
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Thresholds for the detection of temporal gaps were measured using two types of signals to mark the gaps: bandpass-filtered noises and sinusoids. The first experiment used seven subjects with relatively flat unilateral moderate cochlear... more
Thresholds for the detection of temporal gaps were measured using two types of signals to mark the gaps: bandpass-filtered noises and sinusoids. The first experiment used seven subjects with relatively flat unilateral moderate cochlear hearing loss. The normal ear of each subject was tested both at the same sound-pressure level (SPL) as the impaired ear, and at the same sensation level (SL). Background noise was used to mask spectral "splatter" associated with the gap. For the noise markers, gap thresholds tended to be larger for the impaired ears than for the normal ears when the comparison was made at equal SPL; the difference was reduced, but not eliminated, when the comparison was made at equal SL. Gap thresholds for both the normal and impaired ears decreased as the center frequency increased from 0.5 to 2.0 kHz. For the sinusoidal markers, gap thresholds were often similar for the normal and impaired ears when tested at equal SPL, and were larger for the normal ears when tested at equal SL. Gap thresholds did not change systematically with frequency. Gap thresholds using sinusoidal markers were smaller than those using noise markers. In the second experiment, three subjects with single-channel cochlear implants were tested. Gap thresholds for noise bands tended to increase with increasing center frequency when the noise bandwidth was fixed, and to decrease with increasing bandwidth when the center frequency was fixed. Gap thresholds for sinusoids did not change with center frequency, but decreased markedly with increasing level. Gap thresholds for sinusoids were considerably smaller than those for noise bands.(ABSTRACT TRUNCATED AT 250 WORDS)
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Peripheral-channeling theorists argue that differences in excitation pattern between successive sounds are necessary for stream segregation to occur. The component phases of complex tones comprising unresolved harmonics (F0=100 Hz) were... more
Peripheral-channeling theorists argue that differences in excitation pattern between successive sounds are necessary for stream segregation to occur. The component phases of complex tones comprising unresolved harmonics (F0=100 Hz) were manipulated to change pitch and timbre without changing the power spectrum. In experiment 1, listeners compared two alternating sequences of tones, A and B. One sequence was isochronous (tone duration=60 ms, intertone interval=40 ms). The other began isochronously, but the progressive delay of tone B made the rhythm irregular. Subjects had to identify the sequence with irregular rhythm. Stream segregation makes this task more difficult. A and B could differ in passband (1250-2500 Hz, 1768-3536 Hz, 2500-5000 Hz), component phase (cosine, alternating, random), or both. Stimuli were presented at 70 dB SPL in pink noise. Dissimilarity in either passband or phase increased discrimination thresholds. Moreover, phase differences raised threshold even when there was no passband difference. In experiment 2, listeners judged moment-by-moment the grouping of long ABA-ABA-... sequences. The measure was the proportion of time a sequence was heard as segregated. The factors that increased segregation were very similar to those that increased threshold in experiment 1. Overall, the findings indicate that substantial stream segregation can occur without differences in power spectrum. It is concluded that differences in peripheral channeling are not a requirement for stream segregation.
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A model for predicting loudness for people with cochlear hearing loss is applied to the problem of prescribing the frequency-gain characteristic of a linear hearing aid. It is argued that a reasonable goal is to make all frequency bands... more
A model for predicting loudness for people with cochlear hearing loss is applied to the problem of prescribing the frequency-gain characteristic of a linear hearing aid. It is argued that a reasonable goal is to make all frequency bands of speech equally loud while achieving a comfortable overall loudness; this can maximize the proportion of the speech spectrum that is above the absolute threshold for a given loudness. In terms of the model this means that the specific loudness pattern evoked by speech of a moderate level (65 dB SPL) should be reasonably flat (equal loudness per critical band), and the overall loudness should be similar to that evoked in a normal listener by 65 dB speech (about 23 sones). The model is used to develop a new formula - the 'Cambridge formula' - for prescribing insertion gain from audiometric thresholds. It is shown that, for a fixed overall loudness of 23 sones, the Cambridge formula leads to a higher calculated articulation index than three other commonly used prescriptive methods: NAL(R), FIG6 and DSL.
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The mechanism(s) determining pitch may assign less weight to portions of a sound where the frequency is changing rapidly. The present experiments explored the possible effect of this on the overall pitch of frequency-modulated sounds.... more
The mechanism(s) determining pitch may assign less weight to portions of a sound where the frequency is changing rapidly. The present experiments explored the possible effect of this on the overall pitch of frequency-modulated sounds. Pitch matches were obtained between an adjustable unmodulated sinusoid and a sinusoidal carrier that was frequency modulated using a highly asymmetric function with the form of a repeating U or inverted U shaped function. The amplitude was constant during the 400-ms presentation time of each stimulus, except for 10-ms raised-cosine onset and offset ramps. In experiment 1, the carrier level was 50 dB SPL and the geometric mean of the instantaneous frequency of the modulated carrier, fc, was either 0.5, 1, 2, or 8 kHz. The modulation rate (fm) was 5, 10, or 20 Hz. The overall depth (maximum to minimum) of the FM was 8% of fc. For all carrier frequencies, the matched frequency was shifted away from the mean carrier frequency, downwards for the U shaped function stimuli and upwards for the repeated inverted U shaped function stimuli. The shift was typically slightly greater than 1% of fc, and did not vary markedly with fc. The effect of fm was small, but there was a trend for the shifts to decrease with increasing fm for fc = 0.5 kHz and to increase with increasing fm for fc = 2 kHz. In experiment 2, the carrier level was reduced to 20 dB SL and matches were obtained only for fc = 2 kHz. Shifts in matched frequency of about 1% were still observed, but the trend for the shifts to increase with increasing fm no longer occurred. In experiment 3, matches were obtained for a 4-kHz carrier at 50 dB SPL. Shifts of about 1% again occurred, which did not vary markedly with fm. The shifts in matched frequency observed in all three experiments are not predicted by models based on the amplitude- or intensity-weighted average of instantaneous frequency (EWAIF or IWAIF). The shifts (and the pitch shifts observed earlier for two-tone complexes and for stimuli with simultaneous AM and FM) are consistent with a model based on the assumption that the overall pitch of a frequency-modulated sound is determined from a weighted average of period estimates, with the weight attached to a given estimate being inversely related to the short-term rate of change of period and directly related to a compressive function of the amplitude.
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Eight subjects with bilateral sensorineural hearing losses took part in a trial comparing listening unaided with listening binaurally through two types of hearing aid, aid A and aid B. Both aids incorporated slow-acting automatic gain... more
Eight subjects with bilateral sensorineural hearing losses took part in a trial comparing listening unaided with listening binaurally through two types of hearing aid, aid A and aid B. Both aids incorporated slow-acting automatic gain control (AGC) operating on the whole speech signal. However, aid A also incorporated two-channel syllabic compression. The two aids were chosen to be as similar as possible in other respects, and both were worn behind the ear. Subjects were tested in a counter-balanced order, and had at least 2 weeks of everyday experience with each aid before testing took place. Performance was evaluated in three ways: by measuring speech intelligibility in quiet for sentences at three peak sound levels, 55, 70 and 85 dB SPL; by measuring the level of speech required for 50% intelligibility (called the SRT) of sentences in two levels of speech-shaped noise, 60 and 75 dB SPL; and by administering questionnaires about experience with the aids in everyday life. Both aid A and aid B improved the intelligibility of speech in quiet relative to unaided listening, particularly at the lowest sound level. However, aid A gave lower (i.e., superior) SRTs in speech-shaped noise than aid B or unaided listening. The questionnaires also indicated that aid A gave better performance in noisy situations. The results strongly suggest that two-channel syllabic compression, combined with slow-acting AGC operating on the whole speech signal, can give superior results to slow-acting AGC alone, particularly in noisy situations.
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This study investigated how effectively audition can be used to guide navigation around an obstacle. Ten blindfolded normally sighted participants navigated around a 0.6 × 2 m obstacle while producing self-generated mouth click sounds.... more
This study investigated how effectively audition can be used to guide navigation around an obstacle. Ten blindfolded normally sighted participants navigated around a 0.6 × 2 m obstacle while producing self-generated mouth click sounds. Objective movement performance was measured using a Vicon motion capture system. Performance with full vision without generating sound was used as a baseline for comparison. The obstacle's location was varied randomly from trial to trial: it was either straight ahead or 25 cm to the left or right relative to the participant. Although audition provided sufficient information to detect the obstacle and guide participants around it without collision in the majority of trials, buffer space (clearance between the shoulder and obstacle), overall movement times, and number of velocity corrections were significantly (p < 0.05) greater with auditory guidance than visual guidance. Collisions sometime occurred under auditory guidance, suggesting that audi...
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ABSTRACT The summation of loudness across ears is often studied indirectly by measuring the level difference required for equal loudness (LDEL) of monaurally and diotically presented sounds. Typically, the LDEL is 5-6 dB, consistent with... more
ABSTRACT The summation of loudness across ears is often studied indirectly by measuring the level difference required for equal loudness (LDEL) of monaurally and diotically presented sounds. Typically, the LDEL is 5-6 dB, consistent with the idea that a diotic sound is about 1.5 times as loud as the same sound presented monaurally at the same level, as predicted by the loudness model of Moore and Glasberg [J. Acoust. Soc. Am. 121, 1604-1612 (2007)]. One might expect that the LDEL would be smaller than 5-6 dB for hearing-impaired listeners, because loudness recruitment leads to a greater change of loudness for a given change in level. However, previous data from several laboratories showed similar LDEL values for normal- and hearing-impaired listeners. Here, the LDEL was measured for normal-hearing and hearing-impaired listeners using narrowband and broadband noises centered on a frequency where the latter had near-normal audiometric thresholds (500 Hz) and at a frequency where audiometric thresholds were elevated (3000 or 4000 Hz). The LDEL was similar for the two center frequencies for the normal-hearing listeners, but was smaller at the higher center frequency for the hearing-impaired listeners. The results were predicted reasonably well by the loudness model of Moore and Glasberg.
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Research Interests: Mathematics, Music, Adolescent, Medicine, Multidisciplinary, and 6 moreHumans, Young Adult, Pitch Perception, Middle Aged, Adult, and Ear
The first two experiments were designed to determine whether mutual suppression in broadband noise increases in strength with increasing overall level. In experiment I masking functions (signal threshold versus masker level) were measured... more
The first two experiments were designed to determine whether mutual suppression in broadband noise increases in strength with increasing overall level. In experiment I masking functions (signal threshold versus masker level) were measured in forward masking as a function of the delay time of a 10-ms signal, both for a broadband noise masker (low-pass filtered at 8 kHz) and for sinusoidal maskers at 1, 2 and 4 kHz. In the latter case the signal frequency equaled the masker frequency. For short signal delays the masking functions were steeper for the sinusoidal masker than for the noise masker. At longer delays the slopes for both masker types decreased and the slopes for the two masker types became more nearly equal. In experiment II we investigated the effect of gating a low-level noise cue with the sinusoidal masker. At the longer signal delays the masking functions had equal slopes for the broadband noise masker and the sinusoidal masker with cue. At short signal delays the masking functions for sinusoidal maskers may be &quot;artificially&quot; steepened, since the subject lacks an effective cue to distinguish the signal from the masker. The equal slopes at longer delays indicate that mutual suppression of the components within a broadband noise does not increase in strength with increasing overall level. In experiment III we attempted to estimate the magnitude of mutual suppression in a broadband noise by comparing masking functions for a broadband noise and for a noise whose bandwidth was 20% of the center frequency. The suppression was estimated to be about 2 dB at 4 kHz and 8 dB at 2 kHz. A simple mathematical expression, suggested by Jesteadt et al. [J. Acoust. Soc. Am. 71, 950-962 (1982)], was found to give an accurate description of the amount of masking produced by the broadband masker as a function of masker level and signal delay.
Research Interests: Mathematics, Physics, Medicine, Multidisciplinary, Humans, and 4 moreNoise, Cues, Time Factors, and Auditory Threshold
Frequency discrimination was measured for a wide range of center frequencies (0.25-8 kHz) using three different tasks. In the first (difference limens for frequency, DLFs) subjects were required to indicate which of two successive tone... more
Frequency discrimination was measured for a wide range of center frequencies (0.25-8 kHz) using three different tasks. In the first (difference limens for frequency, DLFs) subjects were required to indicate which of two successive tone pulses was higher in frequency. In the second (difference limens for change, DLCs), two successive pairs of tone pulses were presented; one pair had the same frequency and the other pair differed in frequency. Subjects were required to indicate which pair differed in frequency. In the third (frequency-modulation difference limens, FMDLs), subjects were required to indicate which of two successive tone pulses was frequency modulated. Modulation rates were 2, 5, or 10 Hz. For frequencies up to 2 kHz, DLFs and DLCs were small (less than 0.6% of the center frequency) and were similar to one another. For frequencies of 4 kHz and above, both DLFs and DLCs increased markedly, but the increase was greater for DLFs. Thus the worsening of performance at high frequencies is greater when subjects are required to indicate the direction of a frequency change than when they just have to detect any change. FMDLs, when expressed relative to the carrier frequency, varied much less with frequency than DLFs or DLCs. At 2 kHz and below, FMDLs were larger than DLFs or DLCs. Above 4 kHz, FMDLs were smaller than DLFs or DLCs. At 2 kHz and below, FMDLs usually worsened with increasing modulation frequency. Above 4 kHz, FMDLs improved with increasing modulation frequency.(ABSTRACT TRUNCATED AT 250 WORDS)
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Moore and Glasberg [(2007). J. Acoust. Soc. Am. 121, 1604-1612] developed a model for predicting the loudness of dichotic sounds. The model gave accurate predictions of data in the literature, except for an experiment of Zwicker and... more
Moore and Glasberg [(2007). J. Acoust. Soc. Am. 121, 1604-1612] developed a model for predicting the loudness of dichotic sounds. The model gave accurate predictions of data in the literature, except for an experiment of Zwicker and Zwicker [(1991). J. Acoust. Soc. Am. 89, 756-764], in which sounds with non-overlapping spectra were presented to the two ears. The input signal was noise with the same intensity in each critical band (bark). This noise was filtered into 24 bands each 1 bark wide. The bands were then grouped into wider composite bands (consisting of 1, 2, 4, or 12 successive sub-bands) and each composite band was presented either to one ear or the other. Loudness estimates obtained using a scaling procedure decreased somewhat as the number of composite bands increased (and their width decreased), but the predictions of the model showed the opposite pattern. This experiment was similar to that of Zwicker and Zwicker, except that the widths of the bands were based on the ERB(N)-number scale, and a loudness-matching procedure was used. The pattern of the results was consistent with the predictions of the model, showing an increase in loudness as the number of composite bands increased and their spacing decreased.
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... Michael J. Shailer and Gregory P. Schooneveldt* Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 ... Moore, B. G J.. Emmerich, DS Monaural envelope correlation perception, revisited:... more
... Michael J. Shailer and Gregory P. Schooneveldt* Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 ... Moore, B. G J.. Emmerich, DS Monaural envelope correlation perception, revisited: effects of bandwidth, frequency separation ...
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This paper describes experiments evaluating and optimizing an automatic gain control system, called dual front-end AGC (abbreviated as D), intended for use in hearing aids. This system has two purposes: (1) to compensate for variations in... more
This paper describes experiments evaluating and optimizing an automatic gain control system, called dual front-end AGC (abbreviated as D), intended for use in hearing aids. This system has two purposes: (1) to compensate for variations in the overall level of speech from one situation to another by slowly changing its gain; (2) to protect the user from sudden intense transients without affecting the long-term gain. This is achieved by using two control voltages to determine the gain. One changes slowly as the input varies in level. Normally this component determines the overall gain. The other comes into operation when an intense transient occurs. It acts rapidly to reduce the gain, avoiding over-amplification of the transient, but its action ceases quickly after the end of the transient. We describe four experiments measuring speech intelligibility for subjects with cochlear hearing loss in which we determine optimum values for two of the time constants of the D system, namely the recovery time of the fast component and the attack time of the slow component. The experiments also compare the D system with linear amplification (L) and &amp;amp;#39;adaptive compression&amp;amp;#39; (A). The results show: (1) for the D system, optimum values are about 80-150 ms for the recovery time of the fast component and 150-325 ms for the attack time of the slow component; (2) in situations where intense transient sounds are present, and there is either no background sound (experiment 1) or continuous speech-shaped noise as a background (experiment 2), the D system gives significantly better performance than the L or A systems. When the background noise is a single voice, reversed in time (experiment 3), the D and L systems give similar performance, and both are markedly superior to the A system; (3) when the level of speech is varied over a range of 30 dB (experiment 4), both D and A systems allow good performance over the whole range of levels. Performance for the L system worsens markedly at the lower levels.