摘要:

Sweep‐tone measurements of front‐cavity resonances in apical stops are reported. Volumes inferred from resonance frequency data are presented as a function of place of articulation. The results indicate that, for post‐dental points of contact, a cavity located under the tongue tip is formed. It is shown that this sublingual cavity plays a very important role in shaping the spectral structure of apical stops.

ISSN:0001-4966    

DOI:10.1121/1.399707

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

Vocal fold contact behavior was examined in separate groups of boys and girls through application of an electroglottograph (EGG). In general, a contact quotient (EGG duty cycle) showed minimal differences within and between boys and girls during sustained production of the vowels /i/, /u/, and /a/. The findings are discussed with respect to the laryngeal behavior of prepubescent children as well as the clinical utility and applicability of the EGG for examining phonatory behavior among young children.

ISSN:0001-4966    

DOI:10.1121/1.399708

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

Yost [J. Acoust. Soc. Am.78, 901–907 (1985)] found that the detectability of a 30‐ms dichotic signal (Sπ) in a 30‐ms diotic noise (No) was not affected by the presence of a 500‐ms dichotic forward fringe (Nπ). Kollmeier and Gilkey [J. Acoust. Soc. Am.87, 1709–1719, (1990)] performed a somewhat different experiment and varied the onset time of a 25‐ms Sπ signal in a 750‐ms noise that switched, after 375‐ms, from Nπ to No. In contrast to Yost, they found that the Nπ segment of the noise reduced the detectability of the signal even when the signal was temporally delayed well into the No segment of the noise and suggested that the Nπ segment of noise acted as a forward masker. To resolve this apparent conflict, the present study investigated the detectability of a brief Sπ signal in the presence of an No masker of the same duration as the signal. The masker was preceded by quiet or an Nπ forward fringe and followed by quiet, an No, or Nπ backward fringe. The present study differs from most previous studies of the effects of the masker fringe in that the onset time of the signal was systematically varied to examine how masking changes during the time course of the complex fringe–masker–fringe stimulus. The results failed to replicate those of Yost in that an Nπ forward fringe reduced the detectability of the signal, and agreed with those of Kollmeier and Gilkey in that thresholds were elevated well after the offset of the Nπ segment of the noise. The addition of an Nπ backward fringe was also shown to reduce the detectability of the signal. Possible reasons for differences between the results of the present study and those of Yost are evaluated. Results are discussed in the context of models of binaural detection.

ISSN:0001-4966    

DOI:10.1121/1.399709

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

A series of three experiments was undertaken to investigate detection of sinusoidal frequency modulation (FM) in the presence of FM at a separate frequency. The first experiment measured detection of modulation for an FM tone with a modulation frequency ( f m) of 6 Hz as a function of carrier frequency ( f c) under three conditions: (1) in quiet, (2) in the presence of a 2500‐Hz pure tone, and (3) in the presence of a 2500‐Hz FM tone withf m=6 Hz, modulating in phase with the signal. Detection of FM in the presence of the second FM tone was worse than for either the signal presented in quiet or in the presence of the unmodulated tone. Threshold varied as an inverse function of frequency separation between the signal and the masker. In the second experiment, FM detection for a signal withf c=1900 Hz andf m=6 Hz was measured as a function of the modulation frequency ( f m=2–18 Hz) of the 2500‐Hz masker tone. FM detection improved significantly with increasing difference between the modulation frequencies of the signal and the masker. The final experiment measured detection of FM for a signal ( f c=1900 Hz,f m=6 Hz) in the presence of a second FM tone ( f c=2500 Hz,  f m=6 Hz) as a function of the relative phase of the 6‐Hz modulators. Detection of FM improved monotonically as a function of increasing phase difference between the two modulators. The results are discussed in terms of modulation detection interference and perceptual grouping.

ISSN:0001-4966    

DOI:10.1121/1.399710

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

The threshold of a 1250‐Hz tonal signal was measured in the presence of five noise bands (each 50 Hz wide, centered at 850, 1050, 1250, 1450, and 1650 Hz) under five conditions of uncertainty about the waveform type (‘‘correlated’’ or ‘‘uncorrelated’’), and/or the specific waveform sample to be presented. The waveform type was correlated when the temporal envelopes of all of the noise bands were the same, and was uncorrelated when the temporal envelope of the band centered on the signal differed from the common envelope of the other bands. At the low‐uncertainty end of the continuum of conditions, the same waveform type was presented throughout an entire block of trials, and, in addition, the same waveform sample was presented on the two observation intervals of a single trial (but changed across trials). At the high‐uncertainty end of the continuum, both the waveform type and the waveform sample were chosen at random for every observation interval. Threshold estimates obtained from trials in which both observation intervals contained the same waveform type were not affected by uncertainty about the waveform sample within a trial, nor by uncertainty about the waveform type introduced across trials. Thus the comodulation masking release, or CMR (the difference in the thresholds obtained with the uncorrelated and correlated waveforms), calculated from these types of trials was robust across all of the uncertainty conditions. However, on those trials in which one correlated interval and one uncorrelated interval were paired, threshold estimates were influenced by a bias for listeners to choose the uncorrelated interval as the signal interval, whether or not it actually contained the signal. This bias reveals the importance of recognizing the contribution of the nonsignal interval in experiments involving masker uncertainty. Parallel results were obtained using the comodulation detection difference (CDD) task. In some conditions, marked individual differences were observed.

ISSN:0001-4966    

DOI:10.1121/1.399711

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

For a group of eight subjects showing stronger than usual irregularities in the level dependence of the quadratic distortion product, the level and phase of the (f2−f1) difference tone were measured using the method of cancellation for three sets of primary frequencies as a function of the primary levels. An additional masker seems to ‘‘linearize’’ the level dependence toward regular behavior. Using data sets produced with and without the additional masker, it is possible to separate two sources of quadratic nonlinearity, one with regular behavior presumably located in the middle ear and another with irregular behavior (similar to that of cubic distortion) presumably located in the characteristics of outer hair cells. Through the ‘‘subtraction’’ of empirically determined patterns from idealized patterns, it is possible to approximate patterns stemming from the inner‐ear source alone.

ISSN:0001-4966    

DOI:10.1121/1.399712

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

Three programs (female voice, jazz music, and pink noise) were reproduced using four different frequency responses and two different sound levels. Fourteen normal hearing subjects listened to the reproductions via earphones and judged the sound quality on seven perceptual scales (loudness, clarity, fullness, spaciousness, brightness, softness/gentleness, and nearness) and a fidelity scale. Significant differences among the reproductions appeared in all scales and could be attributed to the differences in frequency response or sound level or both. Interactions between the reproductions and the programs could be explained by the relations between the spectrum of the programs and the frequency responses used. The results for the noise program were similar to those for the jazz music program.

ISSN:0001-4966    

DOI:10.1121/1.399713

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

The detection of sinusoidal amplitude modulation (SAM) provides a lower bound on the degree to which temporal information in the envelope of complex waveforms is encoded by the auditory system. The extent to which changes in the amount of modulation are discriminable provides additional information on the ability of the auditory system to utilize envelope fluctuations. Results from an experiment on the discrimination of modulation depth of broadband noise are presented. Discrimination thresholds, expressed as differences in modulation power, increase monotonically with the modulation depth of the standard, but do not obey Weber’s Law. The effects of carrier level and of modulation frequency are consistent with those observed in modulation detection: Changes in carrier level have little effect on modulation discrimination; changes in modulation frequency also have little effect except for standards near the modulation detection threshold. The discrimination of modulation depth is consistent with the leaky‐integrator model of modulation detection for standards below −10 dB (20 log ms); for standards greater than −10 dB, the leaky integrator predicts better performance than that observed behaviorally.

ISSN:0001-4966    

DOI:10.1121/1.399714

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

Fourteen prelinguistically profoundly hearing‐impaired children were fitted with the multichannel electrotactile speech processor (Tickle Talker) developed by Cochlear Pty. Ltd. and the University of Melbourne. Each child participated in an ongoing training and evaluation program, which included measures of speech perception and production. Results of speech perception testing demonstrate clear benefits for children fitted with the device. Thresholds for detection of pure tones were lower for the Tickle Talker than for hearing aids across the frequency range 250–4000 Hz, with the greatest tactual advantage in the high‐frequency consonant range (above 2000 Hz). Individual and mean speech detection thresholds for the Ling 5‐sound test confirmed that speech sounds were detected by the electrotactile device at levels consistent with normal conversational speech. Results for three speech feature tests showed significant improvement when the Tickle Talker was used in combination with hearing aids (TA) as compared with hearing aids along (A). Mean scores in the TA condition increased by 11% for vowel duration, 20% for vowel formant, and 25% for consonant manner as compared with hearing aids alone. Mean TA score on a closed‐set word test (WIPI) was 48%, as compared with 32% for hearing aids alone. Similarly, mean WIPI score for the combination of Tickle Talker, lipreading, and hearing aids (TLA) increased by 6% as compared with combined lipreading and hearing aid (LA) scores. Mean scores on open‐set sentences (BKB) showed a significant increase of 21% for the tactually aided condition (TLA) as compared with unaided (LA). These results indicate that, given sufficient training, children can utilize speech feature information provided through the Tickle Talker to improve discrimination of words and sentences. These results indicate that, given sufficient training, children can utilize speech feature information provided through the Tickle Talker to improve discrimination of words and sentences. These results are consistent with improvement in speech discrimination previously reported for normally hearing and hearing‐impaired adults using the device. Anecdotal evidence also indicates some improvements in speech production for children fitted with the Tickle Talker.

ISSN:0001-4966    

DOI:10.1121/1.399715

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP

摘要:

This study describes a method for recording the electrically evoked, whole‐nerve action potential (EAP) in users of the Ineraid cochlear implant. The method is an adaptation of one originally used by Charlet de Sauvageetal. [J. Acoust. Soc. Am.73, 615–627 (1983)] in guinea pigs. The response, recorded from 11 subjects, consists of a single negative peak that occurs with a latency of approximately 0.4 ms. EAP input/output functions are steeply sloping and monotonic. Response amplitudes ranging up to 160 μV have been recorded. Slope of the EAP input/output function correlates modestly (approximately 0.6–0.69) with results of tests measuring word recognition skills. The refractory properties of the auditory nerve were also assessed. Differences across subjects were found in the rate of recovery from the refractory state. These findings imply that there may be difference across subjects in the accuracy with which rapid temporal cues can be coded at the level of the auditory nerve. Reasonably strong correlations (approximately 0.74–0.85) have been found between the magnitude of the slope of these recovery curves and performance on tests of word recognition.

ISSN:0001-4966    

DOI:10.1121/1.399716

出版商:Acoustical Society of America    

年代:1990

数据来源: AIP