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Journal of the Acoustical Society of America

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Dec 1991

Volume 90, Issue 6, pp. 2891-3397

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Computation of the equivalent modal impedance matrix of a multiple degree of freedom electroelastic structure using antiresonance modes

Jean N. Decarpigny, Bernard F. Hamonic, and Jean C. Debus

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2891-2894 (1991); (4 pages)

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In a recent paper [M. P. Johnson, J. Acoust. Soc. Am. 88, 1–6 (1990)], Johnson presented an interesting approach for connecting a finite‐element model and a multiport network model of a piezoelectric transducer. Thus using one of the several simple numerical tools designed to analyze the electromechanical behavior of a transducer described by a multiport network model, it remains possible to obtain the accuracy otherwise provided by a finite element model. To do this, Johnson built up a modal impedance matrix representation of the transducer structure, starting from finite‐element equations, but the diagonal modal stiffness part of the matrix obtained is perturbed by additional piezoelectric stiffness terms that can induce a more or less complex coupling between modes. The aim of this paper is to demonstrate that, starting with antiresonance modes instead of resonance modes provided by the finite‐element modeling to build up the impedance matrix, avoids the occurrence of these complex coupling terms and, thus, gives the desired simple formulation to the approach.
Show PACS
43.38.Ar Transducing principles, materials, and structures: general
43.38.Fx Piezoelectric and ferroelectric transducers
43.30.Yj Transducers and transducer arrays for underwater sound; transducer calibration

Edge‐less short‐pulse piezoelectric transducers

Dov Hazony

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2895-2900 (1991); (6 pages)

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The behavior of a thin transducer is analyzed when the electroded section constitutes a small part of the available areas. The principal signals are relatively short stress pulses. It will be seen that these pulses may travel close to or at the speed of sound in an unbounded medium and that circuit models may be associated with these transducers. The results also apply to the analysis of elastic properties of thin plates when the aperture of the probing beam is wider than the thickness of the plate.
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43.38.Ar Transducing principles, materials, and structures: general
43.38.Fx Piezoelectric and ferroelectric transducers
43.40.Dx Vibrations of membranes and plates

Direct digital‐to‐analog conversion of acoustic signals using a solid dielectric transducer/filter system

M. Scott Morgan and Lee N. Bolen

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2901-2908 (1991); (8 pages)

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This paper describes the theory, construction, and operation of a transducer that is capable of transmitting an analog acoustic signal when driven by a digital input signal. The digital signal drives a capacitive dielectric transducer whose active surface area is proportional to the magnitude of the digital signal. The output of the transducer contains the original digitized analog signal in addition to higher frequency Fourier components that result from the sampling process. The unwanted additional signal is attenuated by coupling the transducer output into an acoustic low‐pass filter whose response is determined by using electrical circuit analysis techniques. The results indicate that the experimental transducer system is useful for generating acoustic signals that have an upper frequency limit of 8 kHz. With suitable modifications, wider frequency performance is attainable.
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43.38.Ar Transducing principles, materials, and structures: general
43.38.Bs Electrostatic transducers
43.20.Ye Measurement methods and instrumentation

Studies of the speech transducing performance of carbon and electret telephone transmitters

James H. James, James H. Maxwell, and Stephen R. Whitesell

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2909-2918 (1991); (10 pages)

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Five studies examined the relative performance of traditional carbon‐type telephone transmitters and newer electret‐type transmitters that have come to replace the carbon‐type in contemporary telephone set designs. Focus is on the validity of the transmit objective loudness rating (TOLR) metric as a predictor of transmitter efficiency in response to real speech input. TOLR is the IEEE recommended metric (IEEE Standard 269‐1983) for objectively characterizing the efficiency with which telephone transmitters convert acoustic energy to electric energy. These studies indicate that the relationship between TOLR and transmitter efficiency for real speech is not the same for carbon and electret transmitters. Relative to what is observed with carbon transmitters, TOLR was shown to underpredict the real speech efficiency of electret transmitters by approximately 3 dB. Two mechanisms are involved in this effect. First, carbon transmitters have a lower peak‐clipping, or compression, threshold than electret transmitters. This difference is not accounted for in the measurement of TOLR where the input signal consists of a swept sine wave whose constant amplitude (sound‐pressure level of 88 dB) is below the compression threshold of carbon transmitters. Second, the efficiency of carbon transmitters, but not electret transmitters, declines during the first minutes after the telephone handset is taken off‐hook. The formal TOLR measurement protocol overestimates carbon transmitter efficiency because the transmitter is characterized immediately after being taken off‐hook, not over a broader period of time which would be more predictive of its efficiency in real use. These results have implications for the choice of TOLR design objectives for electret transmitter telephone sets. The greater relative efficiency of electret transmitters for real speech input also needs to be considered when grade‐of‐service models, which now assume the use of carbon transmitter telephone sets, are used to estimate the transmission quality of network connections.
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43.38.Si Telephones, earphones, sound power telephones, and intercommunication systems
43.38.Bs Electrostatic transducers
43.72.Kb Speech communication systems and dialogue systems

Dynamics of an ultrasonic bonding tool: A case study in p‐version finite‐element analysis

Rael B. Morris, Paolo Carnevali, and William T. Bandy

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2919-2923 (1991); (5 pages)

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A recently developed p‐version finite‐element program [Bagus et al., IBM Res. Div., Res. Rep., RJ 7733 (71598), October 1990; Carnevali et al., in preparation] was used to simulate the dynamic behavior of an ultrasonic bonding tool. The accuracy of the p‐code was exploited to resolve high‐order modes near to the ultrasonic operating frequency (approximately 60 kHz). In particular, an undesired high‐order bending mode was found to occur at a frequency very close to the axial mode that facilitates the bonding process. An optimal operating frequency that minimizes the excitation of the deleterious mode could be determined. Frequency response simulations and experiments were performed to validate this assertion. Their nature, and the accuracy required to resolve these high‐order modes, would have made this analysis extremely difficult with other finite‐element tools.
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43.58.Ta Computers and computer programs in acoustics
43.35.Yb Ultrasonic instrumentation and measurement techniques

Measurements of ultrasonic pulse arrival time differences produced by abdominal wall specimens

Yoichi Sumino and Robert C. Waag

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2924-2930 (1991); (7 pages) | Cited 9 times

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The influence of propagation medium inhomogeneities on pulsatile ultrasonic fields has been investigated experimentally. The study employed a special curved transducer to produce a hemispherical wave pulse and a linear array to measure the resulting field along a line in a plane. Translation of the array in the elevation direction yielded data over a two‐dimensional aperture. Time delay across the aperture was calculated by adding delay differences obtained by cross‐correlating signals on adjacent elements and noting the position of the cross‐correlation peaks. Received waveforms were shifted an amount given by the difference between the actual arrival time and a calculated geometric delay to isolate arrival time differences due to propagation path inhomogeneities. Waveform and time delay difference plots as well as histograms and statistics derived from them for propagation through a water path and for propagation through five specimens of human abdominal wall indicate that arrival time fluctuations in the presence of human abdominal wall specimens are significantly greater than for a water path and that degradation in focusing through human abdominal wall can be expected in ultrasonic imaging systems that operate in the low megahertz range and employ a relatively large aperture.
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43.80.Cs Acoustical characteristics of biological media: molecular species, cellular level tissues
43.80.Ev Acoustical measurement methods in biological systems and media
43.80.Qf Medical diagnosis with acoustics

Intrinsic echolocation capability of Hector’s dolphin, Cephalorhynchus hectori

C. William Thorpe, Richard H. T. Bates, and Stephen M. Dawson

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2931-2934 (1991); (4 pages) | Cited 2 times

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A sonar system’s echolocation capabilities can be inferred from the ambiguity distribution (defined here in terms of the conventional signal response function) of each of its transmitted signals. Several records of sounds emitted by Hector’s dolphin are analyzed. The computed ambiguity distributions indicate that the sonar clicks of Hector’s dolphins should be capable of resolving the ranges of targets as close together as 2 cm apart, but that target velocities cannot be resolved to any useful degree from a single echo.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
43.80.Jz Use of acoustic energy (with or without other forms) in studies of structure and function of biological systems

Nonuniform beams with harmonically related overtones for use in percussion instruments

Felipe Orduña‐Bustamante

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2935-2941 (1991); (7 pages) | Cited 6 times

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See Also: Erratum

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Beams used in certain percussion instruments with definite pitch such as marimba, xylophone, and vibraphone are undercut in order to bring the frequencies of the first few overtones into a harmonic relationship with the fundamental frequency. This paper addresses the problem of determining the optimal dimensions of the undercut so that the frequencies of modes 2 and 3 of transverse motion are harmonically related with that of the fundamental (mode 1). The undercut is assumed to have a parabolic shape described by two variable parameters related to its depth and width. The rest of the beam on each side of the undercut is assumed to be uniform. Seven pairs of optimal undercut parameters are found that bring the frequencies of the first three transverse modes into the harmonic (integer) ratios 1:3:6, 1:4:8–9, and 1:5:10–13. Calculations performed with and without taking into account the effects of rotary inertia and shear stress are compared against measurements taken from a set of experimental beams. The comparison shows that including the effects of rotary inertia and shear stress results in a better prediction of the optimal parameters of the undercut.
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43.75.Kk Bells, gongs, cymbals, mallet percussion, and similar instruments

Central, auditory mechanisms of perceptual compensation for spectral‐envelope distortiona)

Anthony J. Watkins

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2942-2955 (1991); (14 pages) | Cited 10 times

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The spectral envelope is a major determinant of the perceptual identity of many classes of sound including speech. When sounds are transmitted from the source to the listener, the spectral envelope is invariably and diversely distorted, by factors such as room reverberation. Perceptual compensation for spectral‐envelope distortion was investigated here. Carrier sounds were distorted by spectral envelope difference filters whose frequency response is the spectral envelope of one vowel minus the spectral envelope of another. The filter /i/ minus /q/ and its inverse were used. Subjects identified a test sound that followed the carrier. The test sound was drawn from an an /itch/ to /qtch/ continuum. Perceptual compensation produces a phoneme boundary difference between /i/ minus /q/ and its inverse. Carriers were the phrase ‘‘the next word is’’ spoken by the same (male) speaker as the test sounds, signal‐correlated noise derived from this phrase, the same phrase spoken by a female speaker, male and female versions played backwards, and a repeated end‐point vowel. The carrier and test were presented to the same ear, to different ears, and from different apparent directions (by varying interaural time delay). The results show that compensation is unlike peripheral phenomena, such as adaptation, and unlike phonetic perceptual phenomena. The evidence favors a central, auditory mechanism.
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43.71.An Models and theories of speech perception
43.71.Qr Neurophysiology of speech perception
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.66.Ba Models and theories of auditory processes

The use of prosody in syntactic disambiguation

P. J. Price, M. Ostendorf, S. Shattuck‐Hufnagel, and C. Fong

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2956-2970 (1991); (15 pages) | Cited 4 times

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Prosodic structure and syntactic structure are not identical; neither are they unrelated. Knowing when and how the two correspond could yield better quality speech synthesis, could aid in the disambiguation of competing syntactic hypotheses in speech understanding, and could lead to a more comprehensive view of human speech processing. In a set of experiments involving 35 pairs of phonetically similar sentences representing seven types of structural contrasts, the perceptual evidence shows that some, but not all, of the pairs can be disambiguated on the basis of prosodic differences. The phonological evidence relates the disambiguation primarily to boundary phenomena, although prominences sometimes play a role. Finally, phonetic analyses describing the attributes of these phonological markers indicate the importance of both absolute and relative measures.
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43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation

Lipreading sentences with vibrotactile vocoders: Performance of normal‐hearing and hearing‐impaired subjects

Lynne E. Bernstein, Marilyn E. Demorest, David C. Coulter, and Michael P. O’Connell

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2971-2984 (1991); (14 pages) | Cited 2 times

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See Also: Erratum

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Three vibrotactile vocoders were compared in a training study involving several different speech perception tasks. Vocoders were: (1) the Central Institute for the Deaf version of the Queen’s University vocoder, with 1/3‐oct filter spacing and logarithmic output scaling (CIDLog) [Engebretson and O’Connell, IEEE Trans. Biomed. Eng. BME‐33, 712–716 (1986)]; (2) the same vocoder with linear output scaling (CIDLin); and (3) the Gallaudet University vocoder designed with greater resolution in the second formant region, relative to the CID vocoders, and linear output scaling (GULin). Four normal‐hearing subjects were assigned to either of two control groups, visual‐only control and vocoder control, for which they received the CIDLog vocoder. Five normal‐hearing and four hearing‐impaired subjects were assigned to the linear vocoders. Results showed that the three vocoders provided equivalent information in word‐initial and word‐final tactile‐only consonant identification. However, GULin was the only vocoder significantly effective in enhancing lipreading of isolated prerecorded sentences. Individual subject analyses showed significantly enhanced lipreading by the three normal‐hearing and two hearing‐impaired subjects who received the GULin vocoder. Over the entire training period of the experiment, the mean difference between aided and unaided lipreading of sentences by the GULin aided hearing‐impaired subjects was approximately 6% words correct. Possible explanations for failure to confirm previous success with the CIDLog vocoder [Weisenberger et al., J. Acoust. Soc. Am. 86, 1764–1775 (1989)] are discussed.
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43.71.Rt Sensory mechanisms in speech perception
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.71.Ky Speech perception by the hearing impaired

The effect of linguistic entropy on speech perception in noise in young and elderly listeners

John C. G. M. van Rooij and Reinier Plomp

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2985-2991 (1991); (7 pages) | Cited 8 times

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The rationale for a method to quantify the information content of linguistic stimuli, i.e., the linguistic entropy, is developed. The method is an adapted version of the letter‐guessing procedure originally devised by Shannon [Bell Syst. Tech. J. 30, 50–64 (1951)]. It is applied to sentences included in a widely used test to measure speech‐reception thresholds and originally selected to be approximately equally redundant. Results of a first experiment reveal that this method enables one to detect subtle differences between sentences and sentence lists with respect to linguistic entropy. Results of a second experiment show that (1) in young listeners and with the sentences employed, manipulating linguistic entropy can result in an effect on SRT of approximately 4 dB in terms of signal‐to‐noise ratio; (2) the range of this effect is approximately the same in elderly listeners.
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43.71.Gv Measures of speech perception (intelligibility and quality)
43.71.Lz Speech perception by the aging
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech

The effects of auditory feedback on the regulation of intraoral air pressure during speech

Jerald B. Moon and John W. Folkins

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 2992-2999 (1991); (8 pages) | Cited 1 time

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Previous experimental evidence has been interpreted as support for regulation of both acoustics and aerodynamics during speech production. One recent perspective is that although speech acoustics may be manipulated, regulation of aerodynamics is a central component of the processes that produce speech. From this perspective, it has been suggested that aerodynamic regulation is given priority over perceptual accuracy. The experiment attempted to test this hypothesis by forcing speakers into a choice between aerodynamic and acoustic regulation. The intensity level of frication (embedded in a carrier phrase) was selectively amplified or attenuated and fed back to the speaker on line. Intraoral air pressure was recorded in order to assess whether or not perturbed auditory feedback would result in aerodynamic compensation. Although compensatory changes in peak intraoral air pressure, pressure duration, and pressure curve area were seen in response to 30‐dB alterations of frication, no systematic effects were seen for smaller auditory manipulations. Further, the compensations were less than what one might expect from a system controlling auditory output. Explanations of these findings and their implications for the control of speech production are offered.
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43.70.Aj Anatomy and physiology of the vocal tract, speech aerodynamics, auditory kinetics
43.70.Bk Models and theories of speech production
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation

Different phase‐stable relationships of the upper lip and jaw for production of vowels and diphthongs

Susan Shaiman and Robert J. Porter, Jr.

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3000-3007 (1991); (8 pages)

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Relational invariants have been reported in the timing of articulatory gestures across suprasegmental changes, such as rate and stress. In the current study, the relative timing of the upper lip and jaw was investigated across changes in both suprasegmental and segmental characteristics of speech. The onset of upper lip movement relative to the vowel‐to‐vowel jaw cycle during intervocalic bilabial production was represented as a phase angle, and analyzed across changes in stress, vowel height, and vowel/diphthong identity. Results indicated that the relative timing of the upper lip and jaw varied systematically with changes in stress and vowel/diphthong identity, while remaining constant across changes in vowel height. It appears that modifications in relative timing may be due to adjustments in the jaw cycle as a result of the compound nature of jaw movement for diphthongs as compared to vowels, with further modifications due to the effect of stress on these compound movements.
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43.70.Aj Anatomy and physiology of the vocal tract, speech aerodynamics, auditory kinetics
43.70.Bk Models and theories of speech production

Reiterant speech as a test of non‐native speakers’ mastery of the timing of French

Andrea G. Levitt

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3008-3018 (1991); (11 pages)

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The reiterant speech of ten native speakers of French was analyzed to develop baseline measures for syllable and consonant/vowel timing for a series of two‐, three‐, four‐, and five‐syllable French words spoken in isolation. Ten native speakers of English, who learned French as a second language, produced reiterant versions of both the French words and a comparable set of English words. The native speakers of English were divided into two groups on the basis of their second language experience. The first group consisted of four university‐level teachers, who were relatively experienced learners of French, and the second group of six less experienced learners of French. The French reiterant imitations of the two groups of native speakers of English were compared to the native French speakers’ productions. The timing patterns of the experienced group of non‐native speakers did not differ significantly from those of the native French speakers, whereas there was a significant difference between these two groups and the group of six less experienced second‐language learners. Deviations from the French baseline measures produced by the less experienced group are discussed in terms of the influence of the timing patterns of English and the literature on a sensitive period for second language acquisition.
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43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation
43.70.Kv Cross-linguistic speech production and acoustics

On the perceptual limits of octave harmony and their origin

Laurent Demany, Catherine Semal, and Robert P. Carlyon

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3019-3027 (1991); (9 pages) | Cited 3 times

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Three subjects were monaurally presented with dyads of simultaneous, frequency modulated, sine tones approximately 1 oct apart. The tones, with carrier frequencies FL and FH, were presented in a background of pink noise and at a low sensation level, so that they were completely resolvable by the subjects’ peripheral auditory filters. In two experiments, subjects had to judge on each trial which of two dyads was inharmonic (FH≠2FL); the relative mistuning of the inharmonic dyad [(FH−2FL)/2FL] was varied independently of FL and could be either positive or negative; FL was fixed within trials in one experiment, and varied within trials (from about 8%–20%) in the other experiment. In both experiments, performance monotonically worsened as FL increased from 300–2000 Hz; in addition, negative mistunings were more often identified as inharmonicities than positive mistunings. In another experiment, a 4I‐2AFC procedure was used to assess the detectability of changes in FH, irrespective of their effect on the perception of harmonicity. Compared to the other two experiments, performance was not the same function of FL, and was much better at high FL. Thus it is concluded that the detection of inharmonicity was limited by factors other than those responsible for fine pitch discriminations. Our results also have implications with respect to the origin of human listeners’ melodic octave templates.
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43.66.Hg Pitch
43.75.Bc Scales, intonation, vibrato, composition

Some effects of auditory grouping factors on modulation detection interference (MDI)

Joseph W. Hall, III and John H. Grose

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3028-3035 (1991); (8 pages) | Cited 24 times

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The ability to detect the existence of amplitude modulation at a target frequency is reduced when amplitude modulation exists at a flanking frequency. This effect has been termed modulation detection interference (MDI) [Yost and Sheft, J. Acoust. Soc. Am. 85, 848–857 (1989)]. One explanation for MDI holds that the masking and target frequencies are grouped together by the auditory system such that it is difficult to analyze the modulation at each frequency separately. The present study investigated conditions where the asynchrony of temporal gating of the target and flanking frequencies was manipulated in order to make the frequencies more or less likely to be grouped together by the auditory system and perceived as originating from a single putative source. A second experimental manipulation attempted to perceptually segregate the masking and target frequencies on the basis of harmonicity or spectral proximity. The results of the experiments indicated that manipulations that were intended to enhance the segregation of the masking and target frequencies reduced the magnitude of MDI effects. This generally supported an interpretation that MDI is related in some way to auditory grouping. A final experiment was performed in which the subject had to detect the presence of amplitude modulation, but also had to identify which of two frequency components carried the modulation. Subjects were often poor in discriminating which of two frequencies was amplitude modulated, even when the modulation itself was clearly audible. It was concluded that part of the MDI effect might be due to the poor ability of the auditory system to associate modulation with the carrier of the modulation. The results of the present study are in agreement with past models of MDI proposed by Yost and his colleagues, but do not necessarily directly support the idea that MDI reflects auditory grouping by common modulation.
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43.66.Lj Perceptual effects of sound
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music

Perception of acoustic source characteristics: Walking sounds

Xiaofeng Li, Robert J. Logan, and Richard E. Pastore

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3036-3049 (1991); (14 pages) | Cited 8 times

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The current study investigated the ability of subjects to perceive source characteristics (the gender of a human walker) of a naturally occurring auditory event (human walking). A number of acoustic properties were measured and subjected to statistical analyses in order to identify those properties that differentiate male and female walking footsteps. A principal component analysis on the statistical properties of the spectral energy distributions then identified two classes of information that were important in determining subject perception of the gender of a walker: (1) the spectral peak which integrates the information about the spectral central tendency of frequency and shape of the spectral peak; and (2) the contribution of high‐frequency spectral components. A follow‐up experiment then manipulated these spectral properties to verify their contributions in the perceptual classification of walker gender. Additionally, the effect of shoe on the gender judgement in walking sequences was assessed by having both male and female walkers wear male’s shoes.
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43.66.Lj Perceptual effects of sound

Effects of the pattern of spectral spacing on the perceptual fusion of harmonics

Brian Roberts and Albert S. Bregman

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3050-3060 (1991); (11 pages) | Cited 16 times

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Harmonic relations are important in the perceptual fusion of frequency components, but other factors can influence how much any given harmonic is integrated into a complex tone. This study considers whether the pattern of spectral spacing can act as such a factor. A complex tone consisting only of odd‐numbered harmonics has a regular harmonic spacing of twice the fundamental frequency. The addition of a single even‐numbered harmonic will locally disrupt this regular pattern. If harmonic relations alone limit the perceptual integration of the added harmonic, it should be as well integrated into the complex as its odd‐numbered neighbors. Subjects were required to ‘‘hear out’’ one of the components of the complex and either to rate its perceived clarity (experiment 1) or to judge its pitch in relation to a pure tone 6% higher or lower in frequency (experiment 2). For a fundamental of 100 or 200 Hz, but not 400 Hz, the even harmonic generally could be heard out more easily than its odd neighbors. It is proposed that the poorer integration of the even harmonic at low fundamentals may result from a cross‐channel comparison of amplitude‐modulation rates at the output of the auditory filterbank.
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43.66.Lj Perceptual effects of sound
43.66.Hg Pitch
43.66.Jh Timbre, timbre in musical acoustics

Gap detection in multiple narrow bands of noise as a function of spectral configuration

John H. Grose

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3061-3068 (1991); (8 pages) | Cited 10 times

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This study sought to differentiate between the effect of stimulus bandwidth and the effect of number of activated auditory channels on gap detection in narrow bands of noise. The aim was to clarify the role of across‐frequency analysis in temporal processing. Experiment 1 established that when total noise bandwidth is held constant at 100 Hz, gap detection improves as stimulus energy is distributed to both lower and higher frequencies. Experiment 2a showed that the effect was smaller, or was absent, when the cumulative stimulus bandwidth was increased from 100 to 200 Hz. Experiment 2b confirmed that the benefit of spectral dispersion for the narrower cumulative bandwidth also held for a higher frequency region. The results suggest that in conditions where the cumulative stimulus bandwidth is relatively narrow and, concomitantly, gap detection is relatively poor, there is an advantage in dispersing the stimulus across a number of auditory channels. The advantage for the distribution of energy across a range of auditory channels may be offset when the spectral spacing of bands exceeds a critical value.
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43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Sr Deafness, audiometry, aging effects

Decrement detection in normal and impaired ears

Christopher J. Plack and Brian C. J. Moore

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3069-3076 (1991); (8 pages) | Cited 10 times

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The smallest detectable duration of a brief decrement in the intensity of wideband noise was measured as a function of the depth of the decrement. In the first experiment, conditions were tested in which the noise before the decrement was more intense than the noise after the decrement, and vice‐versa. These data were used to estimate the shape of an intensity‐weighting function, or temporal window, describing the temporal resolution of the ear. The equivalent rectangular durations (ERDs) of the temporal windows measured in this way had values of about 5.5, 4.6, and 6.6 ms for noise spectrum levels of 10, 30, and 50 dB, respectively. In a second experiment, decrement detection was measured in subjects with unilateral sensorineural hearing loss. One set of thresholds was measured in the impaired ear, and two sets of thresholds were measured in the normal ear; one with the noise level at equal SPL to the level in the impaired ear, and one with the noise at equal SL. Temporal window shapes were also estimated from these data. Only one of the subjects showed reduced temporal resolution in the impaired ear, the other two subjects having similar ERD values for all three conditions.
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43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Ba Models and theories of auditory processes
43.66.Sr Deafness, audiometry, aging effects

Lateralization of low‐frequency tones: Relative potency of gating and ongoing interaural delays

Thomas N. Buell, Constantine Trahiotis, and Leslie R. Bernstein

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3077-3085 (1991); (9 pages) | Cited 17 times

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Several types of interaural delay can affect the lateral position of binaural signals. Delays can occur within the gating (onset and/or offset) or ongoing portions of the signal, or both. Extent of laterality produced by each of these delays was measured for low‐frequency tones with an acoustic pointing task. Relative potency was assessed by presenting the delays singly or in combinations (where the types of delay were consistent or in opposition). Rise/decay time, duration, and frequency of the tonal targets were also varied. The major finding was that ongoing delays were much more potent than gating delays in determining extent of laterality. Gating delays were most effective when the interaural phase of the ongoing portion of the tones was more or less ambiguous with respect to which ear was leading. Many of our findings are qualitatively well described by considering properties of patterns of activity produced within a cross‐correlation network by such interaurally delayed signals.
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43.66.Pn Binaural hearing
43.66.Ba Models and theories of auditory processes
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music

Risk factors for hearing loss at different frequencies in a population of 47 388 noise‐exposed workers

Peter Bauer, Karl Körpert, Manfred Neuberger, Alfred Raber, and Friedrich Schwetz

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3086-3098 (1991); (13 pages) | Cited 1 time

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Weighted regression analysis was applied to determine the dependence of the hearing thresholds of 47 388 noise‐exposed workers on age, sex, noise imission level, ear disease, head injury, tinnitus, hearing protector usage, and audiometric frequency in the range from 0.5 to 6 kHz. It could be shown that the hearing thresholds at any frequency are dominated by the age of the worker and that women, after equivalent exposure conditions, hear better than men. The relative effects of sex, noise imission level, ear diseases, tinnitus, and hearing protector usage are related to the audiometric frequency. Users of hearing protectors at the last audiometric investigation hear worse than nonusers. Hearing protector usage is strongly related with the hearing threshold in the low‐frequency range. The noise imission level does not noticeably affect the hearing threshold below 3 kHz. The most important frequency of the noise imission level is as expected 4 kHz. For 4 kHz, it was shown that the variables age, noise imission level, tinnitus, head injuries, and ear diseases act in a good approximation additively on the pure‐tone hearing threshold.
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43.66.Sr Deafness, audiometry, aging effects
43.66.Vt Hearing protection

Nonparametric estimation of phase variance in auditory‐nerve fiber’s responses to tonal stimuli

Li Deng

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3099-3105 (1991); (7 pages)

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Statistical estimation of the phase variance from the auditory‐nerve fiber’s action potential timing data is studied in this paper. A detailed derivation of the sample‐based estimation formulas, which deals specifically with the circularity of the phase variable, is given. The development of the estimator is based on nonparametric statistical inference techniques, making no assumptions on the parametric form of the phase distribution (i.e., shape of period histogram). Some desirable properties of the estimator are demonstrated through numerical examples and applications of the estimator in auditory research are discussed.
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43.64.Pg Electrophysiology of the auditory nerve
43.64.Yp Instruments and methods

Simulations of cochlear nucleus neural circuitry: Excitatory–inhibitory response‐area types I–IV

J. E. Arle and D. O. Kim

J. Acoust. Soc. Am. Volume 90, Issue 6, pp. 3106-3121 (1991); (16 pages)

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Several circuitry schemes have been explored among model stellate and fusiform cochlear nucleus neurons in an effort to reproduce excitatory–inhibitory response‐area (EIRA scheme) types I–IV. Single cell models incorporated known nonlinear membrane properties and spike‐discharge characteristics, as described in previous modeling and intracellular recording. In addition, a unique method of implementing dendritic electrotonic distance processing was developed that provides greater computational efficiency, but with results similar to compartmental models. As an initial simple case, results were examined for a 5‐kHz pure tone. Auditory nerve (AN) population responses across characteristic frequencies from 200 Hz to 50 kHz based on actual single unit recordings were incorporated into the model as input. The findings and conclusions are (1) relatively simple inhibitory connections among stellate and fusiform cells, all of which receive AN excitatory inputs, can account for the salient features of EIRA‐scheme types I–IV; (2) both types III and IV may be obtained using fusiform cells with small adjustments in the anatomical connections; (3) if stellate cells laterally inhibit their own neighbors, they can create inhibitory sidebands, but may have difficulty avoiding multiple sidebands; (4) in the model, type II cells are not responsive to broadband noise but rather to pure tones, and the reason for this was partly because the type II cells were inhibited by other CN units, and partly because the simulated AN fiber response to broadband noise was near their threshold; and (5) the type IV complex response areas may actually arise not necessarily because of elaborate circuitry, but as a result of a complex AN fiber population profile at high stimulus levels in conjunction with the type II inhibitory input to the type IV cells.
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43.64.Qh Electrophysiology of the auditory central nervous system
43.64.Bt Models and theories of the auditory system
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