bluuebunny/crossref_metadata_2025 huggingface dataset:
Loudness-level and summation of amplitude varying octave bands of pink noise
Authors: Jones B. L. , Torick E. L.
Published: October 2005

A series of studies was undertaken to determine the loudness-level of signals whose amplitude changes 10 dB in 1.3-dB discrete steps. Eight different test signals were compared with a steady-state reference signal and with each other at duration times from 0.5 to 10 s. Listeners determined equal loudness points using the two-alternative forced-choice technique. Loudness-level of amplitude varying signals is determined by their envelope shape rather than by whether they are increasing or decreasing in intensity. Order and duration had little effect on loudness-level. Loudness summation did not change significantly over time with experienced listeners. Loudness enhancement did not change until an intraburst interval of approximately two seconds had been reached. The former results agree with Zwislocki et al. [J. J. Zwislocki, I. Ketkar, M. W. Cannon, and R. H. Nodar, Percept. Psychophys. 16, 91–95 (1974)]; the latter would not have been predicted over durations as long as 2 s.
Cross-sensor beamforming for a U-shaped array
Authors: Bucker Homer P.
Published: October 2005

A U-shaped array can be made using two surface floats, an underwater anchor, the line of sensors, and a horizontal fish line to maintain array configuration. Conventional beam forming of this array will result in side-lobe problems. It will be shown how cross-sensor beamforming can be used to detect weak acoustic targets that have lower levels than the side lobes of stronger targets.
Individual module directivity pattern calculation for elements of a close-packed array
Authors: Thompson Stephen C.
Published: October 2005

The radiation pattern of a single transducer can be calculated in many cases of interest. However when several such transducers are arranged in a close-packed array, mutual impedance effects modify the individual element directivities. The effects are pronounced near the element resonance frequency, where such arrays are commonly operated. It has been standard practice to use measured individual element patterns when accurate beam pattern calculations and optimizations are undertaken. Thus the array must be built before its optimal performance can be predicted, making geometrical changes to the design difficult and expensive. This paper presents a method of including the mutual impedances in the individual element directivity calculation. For an array of N elements the method produces a set of 2N linear equations for the real and imaginary parts of the response of each element when the excitation frequency and plane wave arrival angle are given. The method requires knowledge of the acoustic mutual impedances between all pairs of elements, the acoustic self-impedances, the mechanical impedance of each of the individual element radiating areas, and the directivity pattern of each element in the absence of all mutual effects.
The role of fading statistics in channel matching
Authors: Neal Edgar H.
Published: October 2005

It is well known that sonar system performance varies considerably when fixed amount of source energy is divided among N diversity signals when the fading is Rayleigh. This paper reviews the Rayleigh results and establishes similar results for chi-square, Rice, and log-normal fading. Performance curves are included for both search and communication systems.
A generalized frequency processor
Authors: Young J. W.
Published: October 2005

The signal received by a Doppler navigation sonar (or radar) has the character of narrow bandwidth noise [F. B. Berger, IRE Trans. Aero. Nay. Elec. ANE-4, 103 (1957)]. The desired information is some characteristic of the spectrum of this process such as the center of power or a higher order moment. A variety of hardware implementations of frequency measurements systems have been used for this purpose, but their relationship to spectral analysis has remained somewhat obscure. In this paper, it is shown using the analytic signal concept that a “frequency discriminator” computes the first moment of the power spectrum. The approach is generalized to develop a signal processing architecture which can compute an arbitrary function of the power spectrum.
Environmental noise in Kentucky
Authors: Broderson A. B. , Coakley W. S. , Edwards R. G. , Jackson T. , Hauser W. P.
Published: October 2005

A state-wide study was conducted pursuant to development of a Kentucky environmental noise regulation, including assessments of noise and attitudes in 20 cities and impacts of regulation on three mineral processing industries. Urban Leq (daytime mean = 59.1 dBA, sigma = 7.4 dBA; nighttime 5.5 dBA lower) was sufficient for significant noise annoyance and a small potential for permanent hearing loss, judged by EPA “Levels Document” Criteria. Surface transportation was responsible for 80% of the intrusive events and 67% of the high annoyance ratings. Citizens considered urban noise sufficiently harmful to outdoor activity, sleep, and communication to warrant regulation but preferred local over state or federal control and fines for revenues over taxes. An estimated 39% of the coal, rock, and asphalt plants in the state (responsible for most of the complaints to state officials) would violate a 63 dBA test limit; engineering control would cost $10.9 million, rising or falling exponentially with the enforcement limit selected. A proposed regulation is now being finalized. [Work supported by the State of Kentucky.]
Environmental noise assessment using short-term equivalent levels
Authors: Commins D. E. , Sirieys J.-P.
Published: October 2005

Several research projects have been conducted to investigate the possibilities which the A-weighted energy equivalent level offers, when assessed over short successive periods of time, to set an objective method for the assessment of aircraft, railway, and highway noise, when considered alone or when compounded. Two main aspects have been developed. From a methodological standpoint, the measurement of Leq over short durations, typically 10–60 s, by reducing the amount of stored data, makes it possible to preserve information on the temporal evolution of an environment and thereby to enrich considerably the interpretation of analytical results. Also, from the basic measures, on can calculate Leq over large periods and have then access to different scales of analysis. From an analytical standpoint, “short Leq's” histograms provide an efficient visualization of noise conditions and make it possible, through adjustments of the time basis, to assess the specific contributions of a group or of a type of sources to the overall environment. In the case of single events, short Leq's are good estimates of their acoustical energies. Moreover, if simultaneous measurements are performed, one can evaluate the impact of a type of source using correlation coefficients. These encouraging results should lead to further developments: Prediction methods can be imagined which would represent a considerable improvement over those which predict overall quantities. Contemporary technology is able to provide very convenient devices towards the measurements of “short Leq's.” Prediction and measurement schemes should result into an overall methodology for the objective description of an environment based upon a simple measure whose accuracy could be adjusted according to the nature of the problem at hand. [Under the sponsorship of the Ministry of Environment, Paris, and of the Transportation Research Institute, Bron, France.]
Vibration and noise prediction of internal combustion engine based on cascade modeling of components
Authors: Ordubadi A. , Lyon R. , DeJong R.
Published: October 2005

In most machinery noise and vibration problems, a model of the machine as a cascade of subsystems excited by the noise (vibration) source(s) may be used in predicting the effect of any modification in the source(s) or vibration transmission paths. In this study, an acoustic-dynamic model of an internal combustion engine is developed. The excitation sources considered were combustion forces and piston slap. For combustion forces, two transmission paths from each cylinder to the engine block were considered; a path through the piston, crank shaft and bearings [R. DeJong, 1976] and another path through the cylinder head. The piston slap was assumed to be transferred to the block through the cylinder wall and upper deck of the cylinder block [T. Oguchi, 1979]. The combustion forces of each cylinder were determined from the engine design and its operating conditions. The piston slap excitation was estimated on the basis of the shape and size of the piston and cylinder and assumed to occur after the combustion. The block vibration and the radiated sound power spectrum of a four cylinder in-line diesel engine were predicted and measured under different operating conditions. The predicted and measured results agreed well above 400 Hz.
A ray model for predicting sound attenuation by double barriers
Authors: Fano P. C.
Published: October 2005

The results of J. Keller's Geometrical Theory of Diffraction and A. Pierce's single and double edge diffraction theories are used to develop a theoretical ray model for predicting noise attenuations by double barriers. Acoustical scale model experiments were conducted to test the validity of the theory. The experimental results are compared with the attenuations calculated using a computer model. It is shown that the double barrier attenuation (above and beyond that due to geometrical spreading) should be calculated by cascading the attenuation caused by each of the two barriers. This contradicts the generally accepted assumption that given two widely spaced barriers located between a source and receiver, only one of them significantly reduces the noise reaching the receiver. [Work supported by NSF and MIT; thesis advisor: Prof. Richard H. Lyon.]
Pitch in speech: A hearing theory approach
Authors: Duifhuis H. , Willems L. F. , Sluyter R. J.
Published: October 2005

The current hearing theory views on perception of pitch in complex sounds converge towards the interpretation that pitch is the result of a psychological pattern recognition process. Pitch is determined by the fundamental of the harmonic sound which spectrum optimally matches that of the complex sound. Goldstein [J. Acoust. Soc. Am. 54, 1496–1516 (1973)] proposed an objective procedure for finding the best fit. We have adapted and extended his procedure in a pitch meter which measures pitch in speech. The most important deviation from Goldstein's procedure is that in our implementation not all components of the complex sound have to be classified as harmonics. A simple criterion, based on the number of harmonics that is classified as a candidate pitch, determines which candidate pitch is selected. Performance of this psychoacoustically based pitch meter compares favorably with that of known algorithms.
Fundamental frequency (F) attributes in the speech of Wernicke's aphasics
Authors: Cooper William E. , Danly Martha , Hamby Suzanne
Published: October 2005

Adult aphasics with localized posterior lesions of the left cerebral hemisphere (Wernicke's aphasics) were examined for deficits in F0 attributes during sentence production. Clinically, such patients are diagnosed as having primary deficit in speech comprehension, with relatively intact articulation. While their spoken utterances exhibit a normal range of F0 values, experimental testing reveals impairment in the production of selected F0 attributes that are influenced by sentential factors. In this study, patients read aloud sentences that had been designed to test sentential properties of F0 in normal speech. Computer-aided acoustical analysis of F0 indicated that normal speakers produce higher F0 values at the beginnings of long versus short single-clause sentences. A corresponding analysis of aphasic utterances for the same sentence materials indicated that these patients produce similar starting values of F0 for sentences of different lengths. In normal speech, the F0 values generally decline throughout the course of a main clause in a declarative sentence, with optional resetting of the declination function at major syntactic boundaries. For Wernicke's speech, a similar pattern of declination was observed, except that resetting accompanied minor as well as major syntactic boundaries, suggesting that the patients program F0 attributes over shorter-than-normal domains. Finally, word substitution errors committed by the Wernicke's aphasics did not perturb the F0 attributes exhibited in their speech, suggesting that the programming of these F0 characteristics proceeds independently of lexical selection. The Wenicke's deficits are discussed in terms of a model of speech planning and execution. [Supported by NIH Grants NS 11408, NS 13028, and the MIT Research Laboratory of Electronics.]
Computer analysis of the language of deaf children
Authors: Parkhurst Barbara G. , Mac Eachron Marian P.
Published: October 2005

The use of a computer parsing system for analyzing speech and language development in deaf children is being investigated. To this end, a computer system (machine) capable of a detailed grammatical analysis of written language was compared with a skilled speech/language pathologist (human>) for agreement in parsing a corpus of written material produced by deaf children ages 10–14 years according to phrase structure. Sentences were preedited for spelling and major punctuation markers with all other errors left intact. In addition to identifying the various phrase types (noun, verb, prepositional, adjectival, adverbial, infinitive and participial phrases, as well as complements), the proportion correct of several of these phrase types was obtained. An overall score of grammatical correctness was also awarded each sample by human and machine. Results showed excellent agreement between human and machine in terms of parsing sentences of the complexity used by deaf children as well as identifying a large number of specific syntactic error types.
Does a listener need to recover the dynamic vocal tract gestures of a talker to recognize his vowels?
Authors: Pisoni D. B. , Carrell T. D. , Simnick S. S.
Published: October 2005

Although it has been reported that vowels are identified better in the context of a CVC syllable than in isolation, the basis for this advantage is still the subject of some controversy. At the Providence meeting of the Society, Fowler and Shankweiler presented the results of a study comparing vowel identification in speech and nonspeech contexts and argued that the advantage observed for vowel identification in CVC contexts was a consequence of the listener's sensitivity to “acoustic patterning in the speech signal that specifies the vocal tract gestures of the talker.” In the present study, we compared the identification of eight vowels presented in isolation to those presented in the following three different CVC contexts: (1) English fricative-vowel-fricative [sVs], (2) Non-English fricative-vowel-fricative [XVX], and (3) Nonspeech-vowel-non-speech [nsVns] that was generated with a broad-band flat spectrum noise source. In contrast with the results of earlier studies, we found that vowel identification was substantially better in isolation than in any of the CVC contexts. This result suggests that dynamic spectral change is probably not a necessary requirement for accurate vowel recognition to be observed. Furthermore, these findings indicate that a listener does not have to “recover” the dynamic vocal tract gestures of a talker to recognize his vowels. [Supported by research grants from NIMH and NINCDS.]
Identification of French vowels
Authors: Gottfried T. L.
Published: October 2005

Studies of the identification of American English vowels have found that vowels are better identified in consonantal context than in isolation [W. Strange, R. R. Verbrugge, D. P. Shankweiler, and T. R. Edman, J. Acoust. Soc. Am. 60, 213–24 (1976)]. This effect of consonantal context has been attributed to dynamic acoustic information in formant transitions. It has also been hypothesized that phonological factors allow syllable-medial vowels to be better identified. In particular, lax vowels are linguistically inappropriate in isolation, therefore identification of them should be poorer in that context. Since phonological factors are language-specific, one might approach the problem by looking at a language whose phonological system is different from English. French is a language where one vowel/e/that is appropriate in syllable-final position is not appropriate medially. This is a phonological constraint that is the converse of English. Four native speakers of French produced the 11 stressed, oral vowels of French. Comparision was made of the identification of the vowels by native French and American subjects. Influences of phonological and acoustic factors are discussed. [Supported by NIMH, NICHD.]
Computer-assisted evaluation of violin tone quality
Authors: Pickering N. C.
Published: October 2005

Ever since electrodynamic audio equipment has been available it has been used to analyze violin tone quality. Despite many man-years of effort, not much has resulted in practical help for the violin maker. Processing of spectral response curves by computer makes possible more meaningful interpretation of resonances and their origin. Several ways of plotting results, both in musical and technical terms, will be shown. One example of an instrument improved by such analysis will be cited.
Improving grand piano tone radiation for surround-type of concert halls
Authors: Conklin Harold A. , Martin Daniel W.
Published: October 2005

Grand pianos with conventionally inclined lids have directional characteristics which are well suited to conventional concert hall listening. However, some recent concert halls, which surround the musical instruments with listeners, present an acoustical problem to all types of directional musical instruments. Special piano tone reflection means have been developed and successfully used to distribute piano tone more uniformly to the listeners in a surround-type of concert hall.
Pressure and free-field calibration of “half-inch” microphones by reciprocity
Authors: Nedzelnitsky Victor , Burnett Edwin D. , Penzes William B.
Published: October 2005

For measurement situations involving sound fields that are not well specified, uncertainties associated with the choice of diffraction correction to be used for a type L (“one-inch” nominal diameter) microphone can exceed errors in its calibration by one to two orders of magnitude. One benefit from use of smaller microphones is reduction of these uncertainties. Facilities at the National Bureau of Standards have recently been developed for free-field and pressure calibration of “half-inch” nominal diameter laboratory microphones by reciprocity. Both facilities use a grounded shield configuration and insert voltage techniques to determine the open-circuit sensitivity of a microphone. User-interactive computer programs provide on-line computations, display, and storage of calibration results. Adaptors are used to perform pressure calibrations in ANSI S1.10-1966, (RI971) couplers from 50 to 20 000 Hz; use of other couplers could extend this range. Free-field calibrations for normal incidence are performed from 2000 to 20 000 Hz; this range can also be extended. These methods are used to determine the differences between pressure and free-field calibrations for various types of microphones, as well as the influence of protective grids of microphones on their free-field calibration.
Precision reciprocity calibration
Authors: Wong G. S. K. , Embleton T. F. W.
Published: October 2005

A precision ac null-detecting arrangement for reciprocity calibration of condenser microphones has been developed. The major components are a seven-decade ratio-transducer with an accuracy of better than 1 ppm, a polarization voltage source of high precision with a stability of better than 10 ppm, and a high-resolution differential-input lock-in amplifier as the null-detector. Microbarometric pressure variations limit the resolution of the existing arrangement to 0.001 dB. Inherent system errors and errors due to variations of the environment are discussed.
Ladder loudspeaker column system
Authors: Zheng Sha Jia
Published: October 2005

This paper describes some ladder loudspeaker column systems with the following characteristics: (1) Equally spaced ladder loud-speaker column. As a result of the study of several methods to expand the vertical polar response at higher frequencies, it becomes evident that an equally spaced ladder array of the component loud-speakers is the most useful and has the following advantages: (i) A wider vertical polar response at middle and higher frequencies and (ii) easy calculation of directively and simple for construction. (2) Unequally spaced ladder loudspeaker column. Based on the analysis (1) above, the vertical polar response of unequally ladder spaced in arithmetical progression array is investigated. The vertical polar responses of the column with five and seven source elements are calculated. The farfield vertical polar response for five source elements are measured. Both calculations and experiments have shown that the new loudspeaker column system is better than the equally spaced ladder loudspeaker column system in so far as to obtain a wider band directivity at higher frequencies is concerned.
An experimental study of sound radiation from circular ducts
Authors: Clark L. R. , Cho Y. C.
Published: October 2005

This paper presents an experimental study of radiation of spinning modes from hyperboloidal inlet ducts and a circular duct with wide baffle. Results include the angle dependent amplitude and phase of radiated acoustic pressure for various single spinning modes. A single mode was produced using an electronically operated spinning mode synthesizer in the Acoustics and Noise Reduction Laboratory at NASA Langley Research Center. The results are compared with prediction made by an exact theory (Y. C. Cho, AIAA Paper No. 79–677). In doing so, data were symmetrized to minimize effects of undesirable modes which may be produced during measurements.
Reciprocity principle in duet acoustics
Authors: Cho Y. C.
Published: October 2005

A reciprocity relation between mode conversion coefficients is derived for reflection or transmission of sound in a duct without mean flow. Such a relation exists as long as (1) the system remains linear, and (2) modes can be defined at duct stations where the incident and the reflected waves or the incident and the transmitted waves are considered. The reciprocity, relation is independent of acoustic properties of discontinuities which cause mode conversions. For the case of transmission, the shape of cross section and the wall impedance of one end of the duct do not necessarily have to be the same as those of the other end. For instance, the reciprocity relation is well-defined for sound transmission in a duct which is composed of a circular cylinder element at one end, a rectangular cylinder element at the other end, and a transition section between the two cylinder elements. Finally, some comments are made on application of reciprocity principle to a flow duct.
Acoustic behavior in two cavities coupled by a waveguide
Authors: Thompson C. , Leehey P.
Published: October 2005

In many problems involving acoustically coupled systems, the method of geometrical acoustics does not apply. Prediction of the pressure behavior using classical reverberation time formuli would yield incorrect results. In this paper, the problem of two cavities coupled by a waveguide is discussed. The acoustical system is analyzed as a boundary value problem. Approximate solutions for the pressure are obtained using the Method of Matched Asymptotic Expansions, MMAE. The solutions are tabulated in terms of a sequence in a small parameter, ε, where ε is a function of a typical cavity height H0, and cavity lengths L0 and L1. It is assumed that L1 is of order λ/2π. The results explain discrepancies between experimental and tabulated results from geometrical acoustics. A discontinuity in boundary height occurs at each of the cavity-waveguide junctions. It is shown that in the region of this discontinuity, there exists a pressure boundary layer. The eigenvalues of the coupled system are shown to be dependent on this microscopic behavior as well as the square of the gradient of the zeroth order pressure solution. Experimental results on isolated modes serve as a check of the method.
Analytical models for shear layer feed-back cycles
Authors: Crighton D. G. , Innes D.
Published: October 2005

Some linear boundary value problems will be set up which contain all the essential ingredients of typical shear layer feed-back cycles, and yet which are susceptible to exact asymptotic analysis. Models of this kind deal fully with the hydrodynamic-acoustic coupling which is the essence of the feed-back loop, and involve none of the usual empiricism. Specific examples will include the familiar edge tone, the two-dimensional wall jet, and flow on one side of a plane containing a two-dimensional slit. The latter case will be considered in detail, a phase-locking condition will be given (leading to the well-known integer plus one-quarter criterion), the eigenvalue relation will be derived and its implications discussed.
A new theory for calculating the plane wave reflection and transmission by fluid-immersed elastic plates
Authors: Graff Karl F. , Klein Charles A. , Kouyoumjian Robert G.
Published: October 2005

The interaction of acoustic waves with plates is an important part of the overall problem of acoustic wave scattering by underwater structures. A flat plate accurately models certain structural components; furthermore by employing ray acoustics its reflection and transmission coefficients can be used to predict the scattering from curved plates. Thus, it is important to select an elastic plate theory capable of displaying the significant modal responses expected, yet mathematically simple enough to permit an analysis of the scattering and diffraction from discontinuities in the plate. Calculations of the reflection and transmission coefficients for water-immersed steel plates based on classical thin plate theory, Lyamshev theory, and Timoshenko-Mindlin theory reveal significant inaccuracies near one or more coincidence angles or at grazing incidence. This motivated the development of a hybrid plate theory in which the flexure and shear responses of Timoshenko-Mindlin theory are combined with the longitudinal response of Lyamshev theory. Reflection and transmission coefficients calculated from the new hybrid theory are found to be substantially more accurate than those calculated from the earlier theories.
Acoustic finite element analysis of the automobile passenger compartment
Authors: Nefske D. J. , Wolf J. A. , Howell L.
Published: October 2005

Interior noise in an automobile vehicle is known to have an important influence on product acceptability and is therefore an important automobile design consideration. Lightweight unibody construction and other automobile weight-saving efforts have been known to result in increased interior noise, particularly noise in the low-frequency range (20-200 Hz). Vehicle testing has indicated strong correlation between panel motion (i.e., vibrating roof, windows, floor, etc.) and this measured noise, and it has been suggested that the noise may be modulated by the passenger compartment cavity resonance. This paper reviews the application of the finite element method for analyzing the acoustics of the passenger compartment and for computing panel-excited interior noise. By modeling the complete structural-acoustic dynamic system, which is comprised of the interior acoustic resonances as well as the vibration modes of the structural enclosure, this analytic method can be used to identify the influence of individual panels on the interior sound pressure field. The capabilities of the method are illustrated by applications to the production automobile, and experimental verifications of the various techniques are presented to illustrate the accuracy of the method.
Influence of preceding [∫] or [s] on stop consonant perception
Authors: Mann Virginia A. , Repp Bruno H.
Published: October 2005

The category boundary on a synthetic [ta]-[ka] continuum has been shown to shift when the syllables are preceded by [∫] or [s]: More velar stops are heard following [s] than [∫] [Mann and Repp, J. Acoust. Soc. Am. 64, S17(A) (1978)]. In a further study of this context dependency, we have investigated whether it is primarily due to the fricative noise spectrum or to the phonetic category assigned to that noise. Each of five fricative noises from a [∫]-[s] continuum was followed, after a 75-ms gap, by each of five syllables from a [ta]-[ka] continuum. Identification results revealed that the phonetic category to which subjects assigned a given noise was the major determinant of how the stop was perceived. Spectral frequency per se had little effect. Thus, two different fricative noises perceived as belonging to the same category had similar effects on stop perception, whereas a given (ambiguous) noise had quite different effects when labeled as [∫] and as [s]. These findings suggest that the basis for the present context dependency does not lie in auditory contrast. However, they are compatible with the view that speech perception mirrors the dynamics of speech production. We conjecture that our subjects drew on intrinsic knowledge of fricative-induced shifts in place of stop consonant articulation, after assigning one of two discrete places of articulation to the fricative. [Work supported by NICHD and BRS.]
Noise intensity and spectrum cues of spoken fricatives
Authors: McCasland George P.
Published: October 2005

The noise of utterance initial/f/ and /θ/ in naturally spoken syllables /fi/ and /θi/ was replaced by splicing-in both /s/ and /f/ noise cut away from spoken /si/ and /∫i/ syllables. The intensity of the replacing noise had been attenuated to the level of the original /f/ and /θ/ noise. A natural sounding /f/ or /θ/ resulted depending upon whether the original fricative had been /f/ or /θ/, respectively. This procedure was previously utilized by the author in relation to intervocalic fricatives (J. Acoust. Soc. Am. 63, S21(A) (1978)] with similar results. These results suggest that the lower noise intensity of spoken /f/ or /θ/ distinguishes them from /s/ and /∫/. The range of noise spectrum variation which is physically manifest in spoken /f, θ, s, ∫/appears to have no perceptual significance for /f/ and /θ/, which are distinguished from each other by the formant transition cues of the vocalic portion of the syllables. However, noise spectrum differences are important cues in the distinction between /s/ and /∫/. This evidence favors the categorization of both /f/ and /θ/ as nonstrident in distinctive feature terminology.
Extraction of vowel information from fricative spectra
Authors: Yeni-Komshian Grace , Soli Sigfrid D.
Published: October 2005

Although steady-state spectra can specify fricative identity, there are variations in the spectra of fricatives produced in different phonetic contexts. We examined whether such variations in initial fricatives of fricative-vowel-fricative-vowel-fricative utterances contain sufficient information for identification of the subsequent vowel. Twelve utterances made by combining fricatives /s. ∫. z. ȝ/ with vowels /i, a, u/, e.g., /sasas/, were recorded from two speakers. Using a computer controlled editing procedure, initial fricative segments of 150 ms, measured back from vowel onset, were excised from each utterance. These segments, equated for amplitude, comprised the stimuli for identification tests. Eight listeners were asked to identify the vowel which had followed each fricative segment in the original utterance, while a second group was asked to identify the fricative. Both groups received an initial identification test, identification tests with feedback, and a final identification test. Initial results show that vowel identification is above chance and improves with feedback, although not to the level of fricative identification. This suggests that sufficient information is present in initial fricative spectra to specify the subsequent vowel.
Further studies of the influence of sentence rate on the closure duration cue for voicing in medial stop consonants
Authors: Miller J. L. , Grosjean F.
Published: October 2005

Previous research has shown that the closure duration cue for a medial voicing distinction, as in the contrast rabid versus rapid, is perceived in relation to the tempo of a carrier sentence: at faster rates of speech, the voicing boundary moves toward a shorter closure duration [R. Port, J. Acoust. Soc. Am. 59, S41–S42 (A) (1976)]. In this experiment, we asked whether the voicing judgment is influenced by the overall rate of the sentence, which depends both on the articulation rate (the rate at which the speech itself is produced) and pause time, or whether it is influenced primarily by only one of those variables. By independently manipulating articulation rate and pause time, we found that articulation rate is a significantly better predictor of voicing judgments than either overall rate or pause time. Furthermore, when we asked subjects to provide subjective estimates of the rate of our experimental sentences, we found that those judgements were also based almost entirely on articulation rate. These results suggest first, that the interpretation of the closure duration cue is influenced by the articulation rate of the sentence, with pause time having little effect and, second, that listeners use the same rate information, namely, articulation rate, both when estimating the rate of the sentence, per se, and when adjusting for rate in processing the closure duration cue. [Work supported by NIH.]
(/b/ → /p/) bul ⅂ (/p/ → /b/)
Authors: Price P. , Lisker L.
Published: October 2005

Much research has been devoted to the quest for invariant features in sets of speech or speechlike sounds that are perceived as somehow “the same.” Yet the acoustic invariance of phonemes is far from demonstrated. Relevant to the acoustic invariance question is an observed asymmetry in the effect of closure manipulation on naturally produced tokens of rapid and rabid. Thus, shortening the /p/ closure has relatively little effect, while lengthening the silenced /b/ closure produces a decisive shift in labeling. [The support of the National Institute of Child Health and Human Development is gratefully acknowledged.]
Adaptation of the category boundary between speech and nonspeech: A consonantal case against feature detectors
Authors: Remez Robert E.
Published: October 2005

Feature detector accounts of speech perception propose that the distinctive features of phonetic analysis define the inventory of perceptual analyzers. In a recent test of this model, the perceptual boundary between a speech and a nonspeech sound was found to undergo adaptation comparable to adaptation of phonetic categories. A feature detector account of this finding requires the implausible extension of the detector inventory to include nonspeech features. This finding therefore offered counterevidence to the detector model. However, the use of vowels as the speech sound suggests that the test may not be valid, given the relative “nonspeech” quality of vowels judged on a variety of perceptual criteria. The present experiment answers this criticism by using synthetic stimuli ranging from the CV /ba/ to a nonspeech buzz in the adaptation paradigm. The stimuli were made by varying the bandwidths of the five formants, from 200 to 650 Hz in 50-Hz steps. The predicted boundary shifts occur in this case, corroborating the original argument against phonetic feature detectors. It would appear, then, that these results undermine the rationale for phonetic feature detectors in speech perception. [Supported by NIMH.]
Acoustic invariance in speech: Simple or complex properties?
Authors: Blumstein Sheila E.
Published: October 2005

Recent research has suggested that invariant acoustic properties characterized by the shape of the short-time spectrum at consonantal release can be derived for place of articulation in stop consonants. Templates were developed to capture these properties and they successfully categorized 83% of stop consonants spoken by different speakers and varying in vowel contexts [S. E. Blumstein and K. N. Stevens, J. Acoust. Soc. Am. 62, 526 (1977)]. However, in addition to their characteristic shape, each of the three properties seems to have a characteristic frequency prominence with low, mid, and high energy peaks corresponding to labial, velar, and alveolar consonants, respectively. Thus, acoustic invariance might be derived from a simple property sensitive to the frequency in which the highest energy peak of the spectrum falls, rather than from a more complex property sensitive to the overall shape of the spectrum. To investigate this question, the same spectra for initial stop consonants analyzed in terms of templates characterizing their overall spectral shape were reanalyzed in terms of the location of their prominent energy peak. Unlike the templates characterizing shape, the frequency template categorized correctly only 53% of the utterances; vowel context effects were found for particular consonants; and overlap between the alveolar and velar categories was found in the frequency range 3000–3500 Hz. Implications for a theory of speech perception are discussed. [Work supported by NIH.]
Onset of frequency specific hearing in the rabbit
Authors: Lenhardt M. L.
Published: October 2005

The onset of the first auditive startle response to frequency modulated linear ramps was studied. Upward and downward ramps, (0.5–0.75, 1–2, and 2–4 kHz) served as stimuli for 50 rabbits from eight litters with five replications. Animals were tested from age 6–l0 days. At 6 days there were no behavioral responses to sound. At day 7 only responses to the 0.5–0.75 kHz ramp was observed. On day 8 responses to 0.5–0.75 and 1–2 kHz were observed. At age 9 days responses to all stimuli were noted and replicated at age 10 days. For all litters, the downward ramps evoked a greater response than upward ramps; in fact downward ramps were equivalent to a response level 1 day earlier than upward ramps for all frequency areas. Although the low frequencies were the first to evoke behavioral responses, the basal portion of the cochlea is the first to mature. The position that the basal turn mediates early low-frequency responses (Rubel, 1978) will be discussed along with neonatal rabbit processing of frequency specific calls.
Actions of glutamate and related substances on the spontaneous activity of afferent nerves in the toad (Xenopus laevis)
Authors: Bobbin R. P. , Morgan D. N.
Published: October 2005

The purpose of the present study was to use the toad lateral line to test whether glutamate mimics the afferent transmitteer at lower concentrations than were used in the guinea pig [R. P. Bobbin, Exp. Brain Res. 34, 389–393 (1979)] and to examine the actions of other putative transmitter substances. The spontaneous activity of a single toad lateral-line stitch was studied using an isolated skin preparation. Ringer's solution was constantly washed over the inner surface of the skin, except for a few minutes before (5 min) and during (7 min) drug testing. Drugs were applied to the end organ by ejection from a microliter syringe. Results indicate that glutamate (1–2 mM) and aspartate (2–5 mM) produced increases in spontaneous activity, whereas higher concentrations produced greater increases followed by decreases in spiking activity. GABA (2–l0 mM), salicylate (2–10 mM), PGE2 (1–5 mM), PGF2a (1–5 mM), and sucrose (2–10 mM) when applied in this manner, produced weak inhibition (GABA, salicylate) or no effect (PG's, sucrose). Salicylate placed in the Ringer's wash (5-mM final concentration) produced a reduction in spontaneous activity and blocked the effects of glutamate. Results appear to be consistent with the hypothesis that glutamate is the transmitter substance released by the hair cells. [Work supported by NIH and The Kresge Foundation.]
Two-tone suppression in the auditory nerve of the cat: Suppression contours
Authors: Javel Eric
Published: October 2005

For frequencies less than 4 kHz, Fourier analysis of period histograms offers a convenient method for extracting information about auditory nerve fibers' responses to complex signals. In the present study, responsiveness to an excitatory tone (F1) was diminished by a suppressor tone (F2). In general, both tones were excitatory. Suppression magnitude was computed from the shift in the Fourier amplitude versus intensity function for F1 caused by the introduction of F2, in fibers whose characteristic frequencies (CF) were less than 6 kHz. In conditions where suppression magnitude was estimable by both Fourier and discharge-rate analyses, the two techniques produced similar values. “Suppression areas” were constructed for fixed-frequency F1 and variable-frequency, constant-intensity F1. For a given F1, suppression was always maximal at F2 = CF. This was true regardless of the position of F1 within the excitatory response area. Suppression contours obtained at different suppressor-tone intensities resembled the iso-intensity contours obtained in response area determinations, but the suppression contours were narrower than iso-intensity discharge rate contours obtained at equivalent intensities of F2. The results support the conclusions that (a) suppression exists throughout a fiber's response area, (b) suppression behavior is independent of overall discharge rate, and (c) suppression is a primary factor in determining which components in a complex signal will dominate a fiber's response. [Work supported by NIH.]
Cochlear nonlinearity and second filter: Relation to cochlear mechanics
Authors: Duifhuis H. , Vorst J. v.d.
Published: October 2005

Auditory data on sharpening, lateral suppression and combination tones can be put in the single framework of a BPNL-model. This consists of a sequence of a linear filter, a time-invariant nonlinearity, and a second linear filter. We have proposed a slightly different physiological model in which nonlinearity and second filter are supposed to occur at the level of mechanical to electrical transduction in the haircell [H. Duifhuis, J. Acoust. Soc. Am. 59, 408–423 (1976)]. The model assumes nonlinear interaction between radial and longitudinal driving forces of the hair cell, and it also used the directional sensitivity of hair cells. We now have attempted to derive the radial and longitudinal driving forces directly from the cochlear traveling wave and a first order approximation of the geometry of the organ of Corti. This reduces the number of free parameters of the original model. If the modified model is to account for the data then it puts additional constraints on the shape of the travelling wave. The tectorial membrane appears to play a significant role.
Cochlear microphonic evidence for mechanical propagation of distortion products (f2-f1) and (2f1-f2)
Authors: Gibian G. L. , Kim D. O.
Published: October 2005

Conflicting conclusions have been drawn regarding cochlear distortion products from cochlear microphonic (CM) studies [e.g., Dallos, The Auditory Periphery (Academic, New York, 1973)], and from neural studies [Kim and Molnar, in The Nervous System, edited by Tower, (Raven, New York, 1975), and Kim et al., Scand. Audiol. (in press)]. The former studies conclude that there are no mechanically propagated distortion products in CM responses for sound pressure levels (SPLs) below 70 dB (re 20 μN/m2). The latter studies however, conclude that the distortion products (f2-f1 and (2f1-f2) are (1) generated in the cochlear region where the primary-frequency responses are both large, and (2) propagate mechanically like single-tone responses over the region apical to the generation region even at low SPLs (e.g., 34 dB). To help resolve this conflict, we measured CM responses in the chinchilla. We sought and found predominant distortion products (f2-f1) and (2f1-f2) by systematic variation of stimulus frequencies and SPLs with distortion frequency near the characteristic frequency (CF) of the recording site (turn two or three). We subsequently varied the distortion frequency around the CF, e.g., by fixing f1 well above the CF and varying f2. We have observed that the distortion amplitude in CM obtained with SPLs as low as 25 dB shows tuning characteristics similar to the single-tone response. We conclude, in agreement with the neural studies, that our CM data reflect mechanically propagating distortion products. Possible explanations for the previous contrary conclusions are discussed. [Supported by NIH Grants NS07498, NS07057, NS00162, RR00396.]
Nearfield brainstem pure tone input-output relationships in guinea pigs expressed as iso-amplitude contours
Authors: Wilpizeski C. , Mikaelian D. , Doghramji K. , Balshi J.
Published: October 2005

Hartley strain guinea pigs (500–800 g) were fitted stereotaxically with permanent unilateral recording electrodes having tips in the acoustic tubercle. Electrode positions were verified subsequently on autopsy. Two to four weeks following surgery, computer-averaged evoked responses to clicks and eight audiometric frequencies from 125 through 16 000 Hz were recorded during the waking state at 10-dB intensity steps. Stimuli were 15-ms duration tone pulses with 5-ms rise-fall times delivered free field at a repetition rate of 3 per s. Amplifier pass band was set at 0.1–100 Hz (time constants of 3 and 600 ms in order to filter out transient responses (AP) and frequency-following responses (FFR). Amplitudes of the dc slow component (SR), which is typically positive-going, were measured from X–Y recorder traces, transformed into logathmic values and plotted at the intersection of each set of intensity-frequency coordinates. Iso-amplitude lines were drawn between equivalent data points and spaced at 0.1 log intervals to yield a topographic display. Advantages of input-output relationships portrayed in this manner would appear to be mainly visual and permits presentation of unwieldy amounts of data in economical form. Use of the contour display as a norm template is illustrated.
Brain stem evoked response (wave V) latency shifts to filtered clicks
Authors: Leppler J. G. , Greenberg H. J.
Published: October 2005

BSER (wave V) latency shifts to filtered click stimuli were measured. A square wave pulse was filtered to obtain clicks centered at 250, 500, 1000, 2000, 4000, and 6300 Hz. The filtered clicks were transduced monaurally to seven subjects at a rate of 10/s at 50, 40, 30, and 20 dB HL. Wave V latencies were measured from the first compression of the stimulus waveform. BSERs were extractable at all frequency and intensity combinations. A decrease in frequency and intensity caused a systematic increase in wave V latency, as well as a depression in waveform amplitude. Wave V latency shifts due to frequency and intensity changes generally agreed with the results of other investigators [A. J. Klein and D. C. Teas, J. Acoust. Soc. Am. 63, 1887–1895 (1978)]
Effects of chronic methylmercury poisoning on detection thresholds and input-output functions in squirrel monkey subjects
Authors: Wilpizeski C. , Wick E. A. , Zook B. C.
Published: October 2005

Squirrel monkeys were fitted stereotaxically with permanent monopolar recording electrodes with tips aimed at the cochlear nucleus region. Small machine screws tapped into the skull served as implanted dural electrodes. Two groups of experimental animals were poisoned gradually with chronic oral doses of methylmercury chloride or hydroxide (mean daily dose of 0.18 mg/kg and mean total dose of 10.5 mg/kg) for a period of 8–157 days. Mean pure-tone threshold values for experimental subjects did not differ significantly from those obtained from nonpoisoned controls when VDLs were measured from brainstem evoked responses. Detection thresholds inferred from cortical evoked responses were significantly poorer by 20–30 dB. Parallel findings occurred in pure-tone input-output functions. Audiometric data from behaviorally conditioned experimental monkeys revealed no significant hearing loss. Examination of temporal bone serial sections failed to show any recognizable cochlear damage, although lesions were seen in the cristae and maculae. Extensive lesions were evident in brain cortex.