摘要:

A model of the mechanism of residue pitch perception is revisited. It is evaluated in the context of some new empirical results, and it is proposed that the model is able to reconcile a number of differing approaches in the history of theories of pitch perception. The model consists of four sequential processing stages: peripheral frequency selectivity, within-channel half-wave rectification and low-pass filtering, within-channel periodicity extraction, and cross-channel aggregation of the output. The pitch percept is represented by the aggregated periodicity function. Using autocorrelation as the periodicity extraction method and the summary autocorrelation function (SACF) as the method for representing pitch information, it is shown that the model can simulate new experimental results that show how the quality of the pitch percept is influenced by the resolvability of the harmonic components of the stimulus complex. These include: (i) the pitch of harmonic stimuli whose components alternate in phase; (ii) the increased frequency difference limen of tones consisting of higher harmonics; and (iii) the influence of a mistuned harmonic on the pitch of the complex as a function of its harmonic number. To accommodate these paradigms, it was necessary to compare stimuli along the length of the SACF rather than relying upon the highest peak alone. These new results demonstrate that the model responds differently to complexes consisting of low and high harmonics. As a consequence, it is not necessary to postulate two separate mechanisms to explain different pitch percepts associated with resolved and unresolved harmonics.

ISSN:0001-4966    

DOI:10.1121/1.420088

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

The perceived lateral position of narrow-band noise (NBN) was studied in a graphic pointer task as a function of the method of compensation for interaural threshold asymmetries in hearing-impaired and normal-hearing subjects. The method of compensation consisted of equal sensation level (EqSL) or equal sound-pressure level (EqSPL) at the two ears within the same subject. The NBN signals were presented at 11 center frequencies with interaural intensity differences (IIDs) that varied from−20to+20 dB.When equalizing by SL, the perceived lateral position is essentially linearly dependent on the degree and direction of asymmetry in asymmetric normal-hearing and hearing-impaired listeners. Equalizing by SPL shows no such dependency but produces images that are lateralized close to the midline. These results reveal that subjects may have adapted to their threshold asymmetries. These results will be discussed in terms of the fitting of binaural hearing aids.

ISSN:0001-4966    

DOI:10.1121/1.420089

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Microphone arrays can improve speech recognition in noise for hearing-impaired listeners by suppressing interference coming from other than the desired signal direction. In a previous paper [J. M. Kates and M. R. Weiss, J. Acoust. Soc. Am.99, 3138–3148 (1996)], several array-processing techniques were evaluated in two rooms using the AI-weighted array gain as the performance metric. The array consisted of five omnidirectional microphones having uniform 2.5-cm spacing, oriented in the endfire direction. In this paper, the speech intelligibility for two of the array processing techniques, delay-and-sum beamforming and superdirective processing, is evaluated for a group of hearing-impaired subjects. Speech intelligibility was measured using the speech reception threshold (SRT) for spondees and speech intelligibility rating (SIR) for sentence materials. The array performance is compared with that for a single omnidirectional microphone and a single directional microphone having a cardioid response pattern. The SRT and SIR results show that the superdirective array processing was the most effective, followed by the cardioid microphone, the array using delay-and-sum beamforming, and the single omnidirectional microphone. The relative processing ratings do not appear to be strongly affected by the size of the room, and the SRT values determined using isolated spondees are similar to the SIR values produced from continuous discourse.

ISSN:0001-4966    

DOI:10.1121/1.420107

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Voice produced on inhaled air is a form of phonation that has received relatively little attention despite its apparent usefulness in the assessment of vocal function. This preliminary investigation was designed to describe the general characteristics of vocalization driven by an ingressive phonatory airflow. Vocal fundamental frequency(F0),electroglottographic (EGG), and airflow measures were examined in 16 normal men and women, who alternated between inspiratory and expiratory voice. MeanF0routinely increased during inspiratory voice segments, shifting on average 5.1 semitones above the subjects’ comfortable expiratory voice frequency. EGG data showed inspiratory voice to be associated with a more symmetrical pattern of vocal fold contact characterized by a prolonged interval of increasing contact. Both short-termF0variability (jitter) and EGG amplitude perturbation were significantly higher during inspiratory voice. Stroboscopic examination of four of the subjects showed caudal displacement of the larynx and lengthened vocal folds associated with inspiratory phonation. The absolute airflow rate was significantly greater for inspiratory phonation, on average 48.5% higher than during normal expiratory voice. It was also found that both inspiratory pulse and falsetto vibratory patterns could be produced by at least some of the subjects, indicating some control over the mode and frequency of vocal fold vibration when driven by an ingressive airflow.

ISSN:0001-4966    

DOI:10.1121/1.420090

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Intraoral air pressure(P0),nasal airflow, and nasal air volume characteristics were determined from 63 adult speakers during production of oral and nasal consonants. The speakers were categorized into two age groups. Young speakers (21 males, 21 females) ranged in age from 18 to 37 years(mean=24);older speakers (10 males, 11 females) ranged in age from 68 to 83 years(mean=75).Speakers produced the syllables /pi/ and /si/ and the word “hamper” at self-determined loudness levels during reiterant speech tasks. Results indicated similar velopharyngeal function between young and older adults as reflected by nasal airflow and air volume measures. Older adults, however, exhibited significantly higher levels ofP0than younger adults during production of /p/ in “hamper.” In addition, (a) male speakers exhibited higherP0than females during production of /p/ in “hamper,” (b) all speakers demonstrated declination ofP0during production of /p/ in “hamper” as a function of word position in the utterance, and (c) male and female speakers exhibited different patterns of nasal air volume during production of “hamper” as a function of word position in the utterance. The intraoral air pressure results suggest differences in respiratory function between young and older speakers. The nasal air volume results suggest a gender specific velopharyngeal declination effect. Implications for velar motor control strategies are discussed.

ISSN:0001-4966    

DOI:10.1121/1.420091

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

The expression of “naming,” “commanding,” “angry,” “frightened,” “pleading,” “astonished,” “satisfied,” “admiring,” “scornful,” and “sad” was studied with the word [saara] spoken by 12 subjects. Using the same connotations, the 120 utterances were categorized by 73 listeners. Most samples were agreed on by 50%–99% of the judges. Most samples of “astonished,” “angry,” “frightened,” and “commanding” were judged as intended, while “pleading” was often confused with “sad,” and “content” with “admiring.” Acoustic differences between the categories were examined forF0,duration, and sound pressure; spectral features of [aa] were visualized with the self-organizing map of Kohonen. Most intraspeaker variation of meanF0,F0range, sound pressure, and duration took place during the [aa] segment. Peak sound pressure, meanF0,and spectral energy distribution of [aa] differentiated among “commanding,” “angry,” “frightened,” “naming,” and “sad.” Specific intonations of the [aa]segment were encountered for “astonished,” “scornful,” and “pleading.” The best-conveyed “admiring” samples were distinguished from “content” by spectral cues for a breathy voice quality.

ISSN:0001-4966    

DOI:10.1121/1.420109

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

This study investigated speaker normalization in perception of Mandarin tone 2 (midrising) and tone 3 (low-falling–rising) by examining listeners’ use ofF0range as a cue to speaker identity. Two speakers were selected such that tone 2 of the low-pitched speaker and tone 3 of the high-pitched speaker occurred at equivalentF0heights. Production and perception experiments determined that turning point (or inflection point of the tone), andΔF0(the difference inF0between onset and turning point) distinguished the two tones. Three tone continua varying in either turning point,ΔF0,or both acoustic dimensions, were then appended to a natural precursor phrase from each of the two speakers. Results showed identification shifts such that identical stimuli were identified as low tones for the high precursor condition, but as high tones for the low precursor condition. Stimuli varying in turning point showed no significant shift, suggesting that listeners normalize only when the precursor varies in the same dimension as the stimuli. The magnitude of the shift was greater for stimuli varying only inΔF0,as compared to stimuli varying in both turning point andΔF0,indicating that normalization effects are reduced for stimuli more closely matching natural speech.

ISSN:0001-4966    

DOI:10.1121/1.420092

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

In an attempt to replicate and extend previous results obtained on a digital piano [B. H. Repp, J. Acoust. Soc. Am.97, 3862–3874 (1995)], the present study analyzed piano tone decay characteristics, musically trained listeners’ interactive adjustments of key overlap times (KOTs) in tone sequences, and samples of pianists’legatoplaying in scales andarpeggion a computer-controlled Yamaha Disklavier. On the whole, the results resembled the earlier findings: In both perception and production, KOTs tended to be longer for high rather than for low tones and for relatively consonant rather than for dissonant successive tones. KOTs also increased as tempo decreased in production, but there was no corresponding effect in perception (where a smaller range of tempi was used). Even though the decay times of the natural piano tones were about twice as long as those of the digital piano used earlier, the average KOTs were not shorter; on the contrary, they were longer in the perception task, while there was little difference in production. Perception of optimallegatodoes not seem to rest on an invariant criterion of acoustic tone overlap, and pianists do not seem to adjust their KOTs substantially when playing on different instruments. However, there were large individual differences in KOTs.

ISSN:0001-4966    

DOI:10.1121/1.420110

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Other than humans, extensive vocal learning has only been widely demonstrated in birds. Moreover, there are only a handful of avian species that are known to be good mimics of human speech. One such species is the budgerigar (Melopsittacus undulatus), which is a popular mimic of human speech and learns new vocalizations throughout adult life. Using operant conditioning procedures with a repeating background task, we tested budgerigars on the discrimination of tokens from two synthetic /ba/–/wa/ speech continua that differed in syllable, but not transition, duration. Budgerigars showed a significant improvement in discrimination performance on both continua near the phonetic boundary for humans. Budgerigars also showed a shift in the location of the phonetic boundary with a change in syllable length, similar to what has been described for humans and other primates. These results on a nonmammalian species provide support for the operation of a general, nonphonetic, auditory process as one mechanism which can lead to the well-known stimulus-length effect in humans.

ISSN:0001-4966    

DOI:10.1121/1.420111

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

In the subject paper Ebenezer and Abraham used the transfer matrix method to investigate the response of a receiver located between a layered dome and a layered baffle. They considered this set as one multilayer system and obtained complicated matrix equations. The purpose here is to show that the sound field and the response of the receiver may be expressed as simple expressions using reflection and transmission coefficients having clear physical meaning.

ISSN:0001-4966    

DOI:10.1121/1.420112

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP