bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of suppression in a simultaneous masking paradigm
Authors: Jesteadt Walt , Javel Eric
Published: October 2005

Houtgast [Acustica 30, 214–221 (1974)] compared the partial masking, or reduction in loudness, of a tone produced by the addition of noise to the suppression of the tone by the noise, as measured in pulsation-threshold and forward-masking paradigms. Because the effective level of the tone was reduced by similar amounts in both cases, Houtgast suggested that both phenomena may reflect the same underlying mechanism. As a further test of this hypothesis, we have measured the effective level of probe tones of various frequencies and intensities in the presence of band pass and high-pass noises. The effective level of the probe tone is defined as the level of a contralateral tone presented in quiet that is required to produce a centered image. For tones below the cutoff of a high-pass noise, partial masking is relatively independent of probe-tone intensity, for intensities less than 75 dB SPL. The data are similar in this respect to two-tone suppression data for single auditory nerve fibers described by Javel, Geisler, and Ravindran [J. Acoust. Soc. Am. 63, (1978), in press]. [Supported by NIH.]
Shadowing and consonantal release
Authors: Castellanos F. X.
Published: October 2005

As reported previously [Porter and Castellanos, J. Acoust. Soc. Am. 61, S91–S92(A) (1977)] subjects shadow (rapidly imitate) a VCV in approximately 225 ms (measured from stimulus closure to response closure). However when subjects produce the CV /ba/ to the same VCV tape, reaction times increase by over 10 ms (measured from stimulus closure to response release.) To determine whether this asymmetry reflects a perceptual constraint or a motor system limitation, or both, subjects were asked to (1) shadow both a VCV and CV tape, (2) “shadow” the initial vowel in the VCV with a continuing labial nasal /m/ and release the closure to a vowel upon hearing the consonant, (3) respond with a CV to VC stimuli, and (4) respond with a VC to CV stimuli. Results suggest that the majority of the “additional” time is required for the initiation of glottal pulsing and motor system organization. [Work supported by NIH.]
Rapid shadowing of vowel-vowel sequences
Authors: Porter R. J. , Lubker J.
Published: October 2005

Porter and Castellanos [J. Acoust. Soc. Am. 61, S91–S92(A) (1977)], recently reported replications and extensions of the classic Russian investigations of rapid shadowing of VCV's. The speed and accuracy of shadowing in these studies implies a rapid, direct conversion of acoustic cues to motor commands. The present study was designed to further investigate this process by determining if (1) vowel sequences would show the same rapid responses and (2) if electromyography might shed additional light on motor organization. Subjects shadowed randomizations of synthetic vowel sequences ([ai, aε, ao] or [iy, ia, io]). Responses were rapid and accurate, with onset of acoustic transition toward the correct response occurring within 200 ms of the end of V1. Additionally, orbicularis oris activity for the rounded V2's was initiated 25 to 100 msec prior to acoustic changes. Comparison of shadowing times to those obtained in other nondiscriminated vocal responses to the same stimuli suggests that: (1) perceptual analysis may be complete near the end of the 60–80 ms vowel-to-vowel transition, and (2) response initiation may overlap or occur immediately upon completion of the perceptual analysis. [Supported by Fulbright-Hays Fellowship and Department of Phonetics.]
Effects of altering vowel feedback on speech movements
Authors: Forrest Karen , Zimmerman Jerry , Moll Kenneth L. , Small Arnold M.
Published: October 2005

Delayed auditory feedback, masking and movement tracking techniques have been used to investigate the role of auditory feedback in speech production. The results of these experiments are not conclusive and questions still remain as to whether auditory feedback plays a role, when it plays a role and how it plays a role in speech production. In the present study it was hypothesized that if acoustic information concerning the articulatory positions relevant to vowel production is used in speech production, then altering vowel information would disrupt the movements to subsequent sounds in a C1V1C2V2 utterance. High-speed cineradiography (150 fps) was used to monitor movements of the jaw, lips, and tongue. During their production of C1V1C2V2 utterances subjects received (1) normal auditory feedback; (2) feedback in which V1 was altered to another vowel; (3) high-level masking noise. Displacements, velocities, and accelerations were calculated for articulatory movements to V1, C2, and V2 in each condition. The relations between the onset of feedback and movement parameters were also assessed. The results are discussed in terms of our hypothesis concerning the role of the acoustic information associated with vowel production in speech.
Categorical features in speech perception and production
Authors: Goldstein Louis
Published: October 2005

Multidimensional scaling analyses of three types of English consonant confusions are reported: consonant substitutions in spontaneous speech errors, CV perceptual confusions and VC perceptual confusions. Two data sets of each of these types are analyzed to assess reliability. Three reliable dimensions emerge in all data sets, corresponding to voicing, stop/fricative, and place of articulation. Representation of consonants in terms of categorical phonological features exhaustively describes what is common to the configurations of different data types, even though there is reliable detail within each data type that is continuous and is not captured by categorical features. Thus, categorical features can be viewed as the components of the internal representation of speech sounds that are common to various perception and production processes. [Work supported by NIH.]
An approach to regulations for residential construction near major sources of traffic noise
Authors: Northwood T. D.
Published: October 2005

It is well known that noise produced by road and rail traffic may seriously affect the habitability of residences nearby. Planning officials and lending agencies therefore need rules for taking the noise into account in assessing proposed new housing. By the same token, developers and builders need a design procedure that will enable them to meet the regulations. The NRC guideline was designed to fulfil these two objectives. It provides, in a form suitable for non-acousticians, a set of simple rules designed to keep the intrusion of traffic noise within acceptable limits. Determining what is acceptable, subjectively, involves two questions: What physical measure provides a good description of fluctuating noises such as road and rail noise? Then, in terms of the selected measure, what limiting levels are acceptable to the people involved? Of the measures currently in vogue, the energy equivalent sound level (Leq) was selected, and a corresponding set of limits for various residential activities (indoors and outdoors) were adopted.
Keeping traffic noise outdoors
Authors: Quirt J. D.
Published: October 2005

Proper design of housing near major traffic routes must include appropriate noise insulation provisions. A guideline has been developed which includes both a model for calculating the outdoor sound level (Leq) from road traffic and a building design procedure. The noise prediction model takes account of many acoustically significant parameters, and incorporates several novel features. The heights of relevant noise sources (tires, truck exhaust, etc.) are allowed for in evaluating the effective source height, which is of obvious importance in assessing the effectiveness of barriers. The barrier noise reduction calculation includes a simple correction procedure to allow for sound coming around the ends of a short barrier. Parameters in the ground attenuation calculation include source height, receiver height, horizontal source-receiver distance, and the height of any intervening barrier. The building design procedure permits selection of appropriate components to provide the required noise reduction for each room. This procedure is based on the “equal power” concept-i.e., if N components transmit sound into a room, each should transmit only 1/Nth of the total sound power.
Predicting changes in area exposed to aircraft noise
Authors: Holger D. K.
Published: October 2005

Sets of numerically generated noise exposure contours are available for the vicinity of most domestic Air Force Bases and many civilian airports. For such bases, a simple method for manually predicting the change in area enclosed by a given noise exposure contour is described. Such predictions are used for determining whether or not a full scale computer rerun is necessary for a given set of operational changes. The method proposed involves first estimating the change in contour value for a given point and then using that change in contour value to estimate the change in area enclosed by a given contour. The results of several full scale computer runs using the USAF NOISEMAP computer program to test the proposed method are presented. [Work supported by USAF OSR.]
Mode coupling in a sound channel with range-dependent velocity profile
Authors: Chwieroth F. S. , Nagl A. , Überall H. , Zarur G. L.
Published: October 2005

The sound propagation problem is considered for an ocean environment with arbitrary range as well as depth dependence. The ocean bottom is permitted to have a gradual slope. For these conditions the wave equation reduces to a set of coupled differential equations for the range dependence. The ocean is segmented both horizontally and vertically. Within each segment the sound speed is taken to vary linearly with both depth and range. The depth equation is first solved at each vertical boundary to yield depth functions which have the form of Airy functions. The coupled range equations are recast into a set of uncoupled equations through a series of transformations; for this purpose the minor range dependence within a given segment of the depth functions has been neglected. The solution to the original coupled equations is found by applying the inverse transformations to the decoupled solution. The effect on the transmission loss of including the coupling terms is considered. Profiles with different horizontal gradients are considered to determine when the full treatment of the wave equation is necessary. The energy transfer between the modes is also examined. [A. N. and H. Ü. were supported by NRL code 8120.]
Beamforming a towed line array of unknown shape
Authors: Bucker Homer
Published: October 2005

Beamforming a curved towed array of known shape is easily done by matching the received signal to the expected signal of an incident plane wave. If the array shape is unknown, the beam pattern can be calculated for the array moving along an assumed space-time curve. The sharpness of this beam pattern is defined as the sum of the squares of the time-averaged beam outputs over all look directions. Next the space-time array curve is adjusted by an interaction procedure until the sharpness is maximum. Sample calculations for simulated and actual data show that this method generates a significantly improved beam pattern, resolves the left-right ambiguity, and—for the sample data example—provides a good estimate of the array space-time curve.
Mixed-signals separation and coda rejection by adaptive beamforming filter
Authors: Shen Wen-Wu
Published: October 2005

A time-domain linear adaptive beamformer (ABF) was developed for operational purposes of increasing the array detection capability and extracting a signal of unknown waveform from noise. The algorithm minimizes squared filter output subject to the constraints which pass energy from steered location. With a proper scheme of time-varying adaptation rate, the ABF achieves significant improvements of not only reducing the unwanted noise but also preventing desired signal from being degraded, using recorded short-period array (19 sensors) data from the Korean Seismic Research Station (KSRS). The ABF is applied here to the problem of mixed-signals separation and coda rejection-passing the initial arrivals of signal and suppressing the scattered energy due to inhomogeneous media along the propagation path. Examples of processed results in wide band as well as in narrow bands from recorded seismic short-period array data will be presented, and discussion will be based on the comparison of output between the beamsteer (time-alignment and average) and ABF processors.
FFT, hydrophone array, Signal Processing technique for removing ocean reverberation and incoherent noise
Authors: Allen Jont B.
Published: October 2005

In a recent paper [Allen, Berkley, and Blauert. J. Acoust. Soc. Am. 62, 912–195 (1977)] a scheme was presented for reducing room reverberation “noise.” In this talk we propose a hydrophone-array version of this processor which we believe would greatly reduce reverberation and noise in the resulting single channel processed signal. The method, which requires multichannel A/D sampling, FFT's, and digital signal processing, assumes that the reverberation is uncorrelated, in frequency bands, for each of the hydrophones. We believe this assumption to be valid in most acoustic reverberant environments (i.e., λ ≪ system dimensions).
New results on the estimation and tracking of the frequencies of sinusoidal signals in noise by use of linear prediction
Authors: Tufts D. W. , Rao R. M. , Kumaresan R. , Jackson L. B.
Published: October 2005

We derive statistical properties of the eigenvectors and eigenvalues of maximum liklihood estimates of the covariance matrix of the input to a linear predictor, which is to be used for frequency estimation and tracking. Bias in the frequency estimates due to multiple sinusoids is explicitly exhibited. Previously unexplained experimental results [B. Widrow et al,, Proc. Letters, Proc. IEEE 65, 169–173 (Jan. 1977)], for the case of multiple sinusoids with disparate amplitudes, are analyzed using the new results. These results also suggest new methods for simultaneous tracking of the frequencies of multiple sinusoids. Such methods are described.
Model parameters for wide time bandwidth sonar signals
Authors: Rodgers G. F.
Published: October 2005

Wide time-bandwidth (TW) product signals have been used historically in radar and communications for practical applications. Matched filter processing gain for these signals is predictable and offers highly attractive performance in the presence of gaussian noise. However, for sonar applications the interfering noise and reverberation cause serious degradation. Random scatterers within the sonar beam generate a signal-like return which degrades matched-filter processing gain. A matrix of model parameters has been generated in this performance study for signal design. The normal ping history shows high volume reverberation at short ranges and low doppler shift. Corresponding low signal-to-reverberation (S/R) is noted at long ranges as the character of signal interference changes to a more nearby gaussian form. Various TW product signals have been studied for FM Slides, Pseudorandom coded sequences, etc., for comparison to unity TW product signals. A range of both SNR and S/R has been used. Results suggest that a real-time composite of wide TW product signal designs is optimum for simultaneous detection at both extremes of search range.
Identification of vowels in velar consonant contexts
Authors: Gottfried T. L. , Strange W.
Published: October 2005

Previous research in our laboratory showed that vowels spoken in labial consonant contexts (/p-p/, /b-b/) were identified significantly better than isolated vowels. The present study investigates whether initial and/or final velar consonants also aid vowel identification. We compared identification of ten American English vowels in nine conditions: /k/-vowel-/k/, /k/-vowel, vowel-/k/, /g/-vowel-/g/, /g/-vowel, vowel-/g/, /p/-vowel-/p/, /b/-vowel-/b/ and isolated vowels. Vowels in /k-k/, /k-/, /-k/, /p-p/, and /b-b/ frames were identified much more accurately than isolated vowels. However, error rates for vowels in /g-g/, /g-/, and /-g/ frames did not differ significantly from isolated vowels. Error rates for vowels in /k-k/, /k-/, and /-k/ were not significantly different from each other, nor were errors for vowels in /g-g/, /g-/, and /-g/ frames. This seems to disconfirm a phonological hypothesis to explain the poorer identification of isolated vowels [T. R. Edman, W. Strange, and J. J. Jenkins, J. Acoust. Soc. Am. 59, S25(A) (1976)]. Possible reasons for the ineffectiveness of /g/ contexts to aid vowel identification are discussed. [Supported by NIMH, NICHD.]
Post-stimulatory pitch shift and its dependence on signal parameters
Authors: Rakowski Andrzej , Hirsh Ira J.
Published: October 2005

The pitch of a short tone pulse may change if the pulse is immediately preceded by a filtered noise [A. Rakowski and A. Jaroszewski, Acustica 31, 326–329 (1974)], or a tone [W. M. Hartmann and B. J. Blumenstock, J. Acoust. Soc. Am. 60, S40(A) (1976)]. The pitch shift of a tone pulse is usually away from the pitch of a preceding stimulus (“pitch repulsion”), but shifts towards the pitch of a leader have also been observed [L. S. Minick, R. Elmasian and R. Galambos, J. Acoust. Soc. Am. 58, S83(A) (1975)]. In the present work the dependence of the effect on frequency difference and time interval between a leading and a probe tone, as well as on the duration and level of both tones has been investigated. The effect is non-monotonic and exists even when the duration of both leading and probe tone is 25 ms. It is suggested that Post-stimulatory Pitch Shift may influence the results of various psychoacoustic experiments involving comparisons of pitch and may also explain some aspects of musical practice.
Backward and simultaneous context effects on frequency discrimination with sinusoidal stimuli
Authors: Pastore R. E. , Friedman C. J. , Barnett M. L.
Published: October 2005

A series of experiments were run to examine context effects on frequency discrimination. The basic task involved a two alternative forced choice in which the interval containing the higher frequency signal was to be identified. One of the intervals always contained an 1800 Hz sinusoid, while the other contained a sinusoid of frequency (1800 + Δf) Hz. The effects of trailing tones was examined. It was hypothesized that depending on its relative frequency, the trailing tone could have three possible effect on performance: it could serve as a reference and improve performance; it could provide backward interference; or it could have no effect on frequency discrimination performance. In order to parallel the second formant transitions and second formants of consonant-vowel syllables, the discriminated tones were 60 ms, while the trailing tones were 240 ms. The additional effects of sinusoids paralleling first formants and first formant transistions were investigated.
Perceptual quantifications in ear dominance perception of pitch
Authors: Pfannebecker B. , Tolhurst G. C.
Published: October 2005

Under dichotic listening conditions, segregation of pitch from the stimulus ear to a preferred ear, a characteristic of ear dominance perception of pitch, was measured for normal hearing listeners. A stimulus tonal sequence similar to that of Deutsch [(D. Deutsch, J. Acoust. Soc. Am. 57, 1156–1160 (1975)] was partitioned into four sequences and played through headphones to listeners. Melodic contour mapping responses graphically produced by the listeners were compared to the actual stimulus sequence as their tonal sequence identification made by an attended ear. Data analyses of this auditory processing behavior show only partial dependency on the physical parameters comprising each stimulus sequence. An ANOVA did show the number of discrete frequency changes in the dichotic stimuli (1, 3, 5, and 7) were significantly different (F3.228 = 5.9, p < 0.001) and that differences in perception were relatively insensitive to tone burst and interburst durational changes in the stimulus. The data analyses did indicate strong dependency on certain nonphysical factors, i.e., musicianship (F1.75 = 7.7, p < 0.008). Two additional nonphysical factors approached statistical significance, i.e., handedness (F1.75 = 3.2, p < 0.08) and the ear to which the listener was attending (F1.75 = 3.1, p < 0.08). The contributions of these latter psychophysical factors to the compelling ear dominance perception suggest that tonal sequence pitch perception may entail diffuse neurophysiological processing.
Interaural time discrimination in cochlear-impaired listeners
Authors: Hawkins D. B. , Wightman F. L.
Published: October 2005

Interaural time just noticeable differences (jnds) were obtained on a group of normal-hearing listeners and four groups of listeners with sensorineural hearing losses. These groups consisted of persons with moderate hearing loss (1) only in the low frequencies, (2) only in the high frequencies, (3) across the frequency range, and (4) only in one ear. The stimuli consisted of computer-generated narrow bands of noise, 450–550 Hz and 3750–4250 Hz, with the paradigm being constant stimulus two interval forced choice. Interaural intensity jnds were also obtained for the same two bands of noise with hearing-impaired listeners who performed poorly on the time discrimination task. The results indicated that (1) the presence of a sensorineural hearing loss inhibits normal processing of interaural time differences in a lateralization paradigm; (2) there are large individual differences in the amount of deficit in lateralization due to a hearing loss; (3) based on a limited number of subjects employed, there is no clear relationship between configuration of loss and performance on interaural time discrimination; and (4) poor performance on interaural time discrimination tasks does not mean that performance on interaural intensity discrimination tasks will also be poor.
Localization accuracy in the horizontal plane
Authors: Cabot R. C.
Published: October 2005

The accuracy and bias of 12 subjects in localizing sound sources in the horizontal plane are described. All tests were performed with unrestricted head motion using band limited pink noise. Unlike most previous localization work, circular statistics were employed for data analysis and the effects of front-rear confusion are examined in detail. The effect of varying stimulus frequency between 500 Hz and 4 kHz was investigated and the results are considered in relation to the tradeoff of interaural amplitude and phase cues. The dependence of both accuracy and bias on stimulus length was studied, showing little improvement for sounds longer than 0.33 s. The perceived directions were biased away from the median plane, the bias being greater for sounds behind the listener than in front. The variability of responses vs. direction follows a cardioid shape, sources behind the listener producing the highest variability. Extensive regression analysis was performed to determine the statistical significance of these dependencies. This also resulted in an empirical model which predicts the perceived direction era sound given its actual direction, frequency, and duration.
Evaluation of simultaneous processing of signals and noise in hearing aids
Authors: Schweitzer Howard C.
Published: October 2005

As part of the VA hearing aid research effort to refine the electroacoustic evaluation of instruments submitted for contract consideration, methods which examine the simultaneous processing of signals and noise are being explored. In a previous report (American Speech and Hearing Association Convention—1977) measurements using stepped-level signals, superimposed on a steady state noise, were described. In the current studies, techniques are presented which analyze the output signal to noise (S/N) ratio across frequencies for specific input S/N ratios. A tracking filter arrangement, as well as a digital real time analyzer, provide pertinent information regarding both the output S/N and the spectral characteristics of hearing and performance under conditions of simultaneous signal and noise processing. The effect of input level is of particular interest in the findings, particularly when comparing aids with and without automatic gain control circuits.
Forward masking using maskers with equal energy
Authors: Penner M. J.
Published: October 2005

Temporal masking of clicks by noise was investigated using a forward masking paradigm. The temporal separation ΔT between the click and the noise ranged from 0.3 to 100 ms. The duration of the noise varied from 3 to 300 ms while its energy remained fixed. For fixed ΔT (ΔT > 3 ms), the masking effect actually increased for the longer less intense noises despite the fact that, for long maskers, there is less masker energy near the signal in time. These results are interpreted in terms of the modified version of the running average hypothesis [M. J. Penner, J. Acoust. Soc. Am. 62, S60(A) (1977)] in which it is argued that the auditory system compresses the stimulus' intensity prior to integrating it. We claim that the compression may reduce the effective intensity of short maskers to such an extent that they do less masking that the longer ones. Such reduction will occur if the time between the masker and signal is long enough so that the effect of compression and integrator shape do not counterbalance each other. [Work supported by NIH.]
Relative duration of stop closure and fricative noise across speaking rate
Authors: Isenberg D.
Published: October 2005

Words distinguished by a fricative-affricate contrast (dish-ditch and lash-latch) were produced in sentence contexts by native English speakers at five successively increasing speaking rates, from their slowest natural rate to their fastest rate possible without misarticulation. Durations of stop closures and fricative noises in the affricate cases, or fricative noises alone in the fricative cases, were measured from oscillograms. Least mean-squares lines relating durations of these acoustic segments to sentence duration were fitted to these data. Slopes of these functions were generally smaller for stop closures than for fricative noises, indicating that stop closures are more stable in duration across speaking rate than are fricative noises. The results are related to recent perceptual studies of the fricative-affricate distinction [e.g., A. M. Liberman, B. H. Repp, T. Eccardt, and D. Pesetsky, J. Acoust. Soc. Am. 62, S78(A)(1977)]. [Work supported by NINCDS and NICHD.]
Models of phonetic words in terms of acoustic features
Authors: Dolanský Ladislav , Zlatoustova Liubov Vladimirovna
Published: October 2005

In this paper, the nature of syllabic stress is investigated. An acoustical analysis of speech signals reveals the nomenclature for the models of phonetic words and the corresponding acoustical features. Stability criteria for these models are considered with respect to the type of the model, its location in the text, and the physical conditions during the production of the speech signal. The work is carried out using comparable Russian and English texts. Such features as variations of pitch, intensity and duration are investigated with the help of various dialects in each language / British and American English, several dialects of Russian / in an effort to establish general and language- and dialect-dependent features of syllabic stress. The relative importance and mutual replaceability of the various features is also evaluated. [This work was carried out at the Laboratory for Structural and Applied Linguistics, Moscow State University, and supported by the MINVUZ-IREX senior scholar exchange program between USSR and USA.]
More transconsonantal context effects on vowel recognition latency
Authors: Martin James G.
Published: October 2005

The stimuli were spoken vowel-constant-vowel sequences in the sentence frame “I say V1 C V2” in which V1 was /a, i/, C was /p,t,k/ and V2 was /u,æ/ in all 12 combinations. Reaction time (RT) of practiced listeners was observed to the assigned final stressed vowel target (V2). Sentence pairs differing only in final target vowel were either (a) cross spliced at the pre-stop-consonant silent interval or (b) left intact. RT was slower to both targets when cross spliced than to their intact counterparts. However, the results were asymmetrical: one target was affected by cross splicing more than the other. This suggests that cross-splice effects were not due to prosodic discontinuity alone, since such discontinuity presumably applies to both sentences equally when crossed. The asymmetry between targets suggests either different amounts of target-specific information preceding the silent interval or a difference in perceptual weight given to information on the two sides of the interval.
An extension of Shaw's theory to conical terminations
Authors: Nagarkar B. N. , Finch R. D.
Published: October 2005

Shaw's theory of sound propagation in acoustic horns with spatially varying density and elasticity is extended to conical terminations. The density variation technique was applied to simulate a conical termination in a tube of uniform cross section using perforated sheet-metal plates. The performance of the density variation horn and the equivalent conical horn was evaluated by comparison of the acoustic impedance and the acoustic pressure within the horns. It was observed that the density-variation conical horn had sound absorbing properties as a result of the use of the perforated plates to simulate density variation. Webster's equation is modified to account for the absorption of the medium. Expressions are developed for the acoustic pressure and the acoustic impedance taking into account the absorption of the medium. The theoretical calculations for the acoustic pressure and the acoustic impedance are in agreement with the experimental results of the density-variation conical horn. Due to the absorption properties of the density variation cone it can be used as a muffler. A prototype muffler was designed such that it would be suitable as an automobile muffler. The performance was evaluated using both a loudspeaker and an internal combustion engine as sound sources.
A sensitivity study of the effects of bottom roughness on low-frequency sound propagation
Authors: Rutherford S. R. , Hawker K. E. , Payne S. G.
Published: October 2005

The sensitivity of the modal attenuation coefficients due to scattering from a randomly rough interface are examined using the formula derived in papers by Kuperman and Ingenito [W. A. Kuperman, J. Acoust. Soc. Am. 58, 365–370 (1975) and W. A. Kuperman and F. Ingenito. J. Acoust. Soc. Am. 61, 1178–1187 (1977)]. The results presented in their papers are specialized to the case of a randomly rough ocean bottom having a Gaussian auto-correlation function. The preliminary calculations were made for clay and sand bottoms for frequencies of 20 and 100 Hz. For the cases studied it was found that, for fixed bottom roughness. the attenuation coefficients increased with frequency as expected, but showed insensitivity to the correlation length of the bottom roughness. It was also determined that, for fixed bottom roughness, the harder sand-type bottom produced more scattering attenuation than a clay-type bottom. [Work supported by Naval Electronic Systems Command.]
Lung airway geometry by pulse response: Consequences of branching asymmetry and nonrigid airway walls
Authors: Fredberg J. J. , Sidell R. S.
Published: October 2005

The summed cross-sectional area of the airway network as a function of distance from the airway opening can be inferred from impulse reflection data measured at the airway opening [Jackson et al., J. Appl. Physiol. 43 (3) (1977)]. We have critically examined this method. This was accomplished by direct comparison of the area inference with anatomic data for a computer model of the complete tracheo-bronchial tree [Fredberg and Moore, J. Acoust. Soc. Am. 63 (3) (1978)]. The results show that the serial distribution of airway geometry is well approximated when the branching is symmetric, airway walls are rigid, and the gas is inviscid. Branching asymmetry causes small differences between the inferred area and the anatomic area mouthward of the most central segmental bronchus, but larger and growing differences beyond that. Non-rigidity of the airway walls causes the area-inference to exceed the anatomic area by 20%–50% at the level of the carina, and more so distally. [Supported by NHLBI contract N01-HR-6-2901].
Hearing Loss from Rock Music
Authors: Cabot R. C. , Genter C. R. , Luche T. R.
Published: October 2005

A mobile testing laboratory was constructed to allow the administration of questionnaires and hearing tests outside of bars and discotéques. Hearing thresholds were measured for 268 subjects and subjects were queried on such factors as age, sex, income, eye color, frequency of attendance at establishments with loud music, occupational noise exposure, and personal music preferences. Sixty-seven of these subjects were retested for TTS over the course of an evening and additionally questioned about alcohol and drug consumption during this period. Tape recordings were made within each test location and analyzed for sound pressure level, peak level and spectral distribution. Data analysis was directed toward isolating predictors of music induced temporary threshold shift and music induced permanent threshold shift. Pre-exposure thresholds were significantly elevated compared to the 1958 normative data, although this elevation was of considerably smaller magnitude than those predicted from several past studies. Thresholds were within the limits of “clinically normal” hearing. A further elevation after exposure was also seen with Composite Damage Risk being the best predictor of the shift. [Supported by NSF]
TTS resulting from hearing-aid usage
Authors: Humes L. E.
Published: October 2005

Two experiments were conducted in which a normal-hearing young adult (the author) wore an ear-level moderate-gain hearing aid under various listening conditions. In the first experiment, a somewhat artificial experimental design was employed which attempted to maximize the risk involved. In the second experiment, amplification was worn in a more realistic environment (a college classroom). Considerable amounts of temporary threshold shift (TTS) were observed in both experiments despite a maximum exposure duration of only two hours. In the initial experiment, for instance, TTS exceeded 40 dB immediately following “exposure” and over 24 h were required for complete recovery. The amount of TTS was dependent primarily upon saturation sound pressure level (SSPL), duration of “exposure,” and frequency of the test signal.
Internal and External Noise in Binaural Detection
Authors: Siegel R. A. , Colburn H. S.
Published: October 2005

In an effort to assess the relative importance of internal and external noise in binaural masking, two tone-in-noise detection experiments have been performed using computer-generated maskers. In the first experiment, masked thresholds for a 500-Hz tone were obtained in a 2IFC paradigm for NOSO and NOSπ under two conditions: (a) with identical maskers in the two intervals and (b) with different maskers in the two intervals. The difference in threshold in the two cases is an indicator of the relative size of the two noise components. In the second experiment, a subset of the noise wave-forms was randomly selected, and sensitivities and biases were measured for each waveform in a one-interval paradigm for NOSπ. The variability of bias across masker waveforms serves as another measure of the relative magnitudes of internal and external noise. In all cases, maskers were presented in random order across trials. We shall discuss the relationship of these data to various models of internal noise and to the theory of binaural interaction based on auditory nerve data. [Work supported by NIH.]1
Features and parameters in interactive synthesis
Authors: Hertz Sue
Published: October 2005

One reason for developing a speech synthesis by rule system is to help linguists and psychologists conduct experiments in the production and modification of speech by application of phonological rules. The Cornell system has two special characteristics. First, minimal theoretical constraints: it does not dictate one particular synthesis strategy. Second, it has a powerful interactive command language for defining, storing, and editing phonetic symbols, features, and rules, and it requires minimal knowledge of computing. More specifically, rules are of two kinds. Feature rules include the kind familiar to linguists. They operate on discrete symbols defined as bundles of features, and yield another discrete representation. Parameter rules transform the discrete representation into a continuous spectral envelope by specifying segment durations, target values for the synthesizer parameters (more than one per segment if necessary), and intervening transition shapes within or across segment boundaries. Although linguists have recognized the need for rules of this sort for such continuously-varying phenomena as intonation, they have not generally recognized their utility for describing phonetic phenomena in the domain of segmental phonology as well.
More on slongue tips
Authors: Fromkin V. A.
Published: October 2005

A preliminary report on the automatic processing of a small sample of the UCLA corpus of speech errors was presented at a previous Meeting of the ASA. 3000 phonological errors—errors which involve only the perseveration, anticipation, reversal, deletion, or addition of phonemic or phonetic segments—have now been processed by SLUNGTIP, the computer program written by G. Silva. The errors are analyzed as to frequency of words versus non-words, units spanned (words, morphemes, syllables, and segments between the intrusive sound and the occurring error), and syntactic categories involved. In addition, alternative feature sets are examined to see which may better account for the confusions which occur. These findings are discussed in relation to models of speech production. [Work supported by NIH.]
Phonological variation over time: Boston /æ/
Authors: Laferriere Martha
Published: October 2005

In the Boston dialect, the phoneme /æ/ has been observed to vary allophonically. To determine if this variation is systematic over time [Labov, 1966], five speakers, ages 26–71, read a list of forty words containing /æ/ before nasals (man), voiced obstruents (bad), voiceless obstruents (fact) and spirants (pass). 1st and 2nd formant values for each occurrence of /æ/ were obtained by computer analysis, and five F1 vs. F2 vowel space plots were made. For the two oldest speakers, /æ/'s are distributed in a broad (700-Hz) range along the F2 axis, and a narrow (200-Hz) range along the F1 axis. /æ/'s before nasals, with the highest F2 values, are the most fronted. For the younger speakers, /æ/'s have the same broad F2 range and narrow F1 range; but for the phonetic subclass of /æ/'s before nasals, F1 values have been lowered by about 400 Hz to overlap with F1 values for the midvowel /e/. These preliminary results suggest that, in formal speech style, phonetic discreteness or continuousness of sound change is governed by directionality of change within the vowel space: variations in tongue fronting (F2) are continuous, whereas variations in tongue raising (F0) are discrete.
A perceptual and acoustic study of the Feʔfeʔ vowel system
Authors: Hombert Jean-Marie
Published: October 2005

Five speakers of Feʔfeʔ (a Bamileke language spoken in Cameroon) read a word list containing the eight Feʔfeʔ long vowels [i, e, a, ɑ, ɔ, u, ʉ, ə] all of which contrast in open syllables. They were asked to listen to 53 synthetic vowel stimuli (in which F1 was varied between 250 and 750 Hz and F2 between 650 to 2350 Hz) according to their own vowel system. After each stimulus presentation they had to indicate which word of the word list “sounded like the sound they just heard.” By doing so Feʔfeʔ speakers were dividing up the vowel space according to their own vowel system. These are a number of cases in which speakers perceptual judgments did not match their productions (in particular with vowels with F2 around 1500 Hz). This suggests an explanation for the relative scarcity of central vowels in the world's languages which is different from an explanation based on maximum perceptual distance. [Work supported by NSF.]
Single-consonant juncture word-pairs in American English
Authors: Baker D. J.
Published: October 2005

Although a number of studies have incorporated pairs of words in the study of juncture, a search of the literature did not reveal any systematic listing of all possible single-consonant juncture word-pairs in American English. This paper discusses the generation of such a list. The words to be paired were derived from the AFCRC TN 55–56, One-Syllable Words, by Moser, Dreher, and Oyer. In this report a three-component array of one-syllable words was used. In column one all Initial consonant sound(s) were listed. followed by successive columns of all Vowel (and diphthong) sounds in American English, which was followed by a final column listing all Terminal consonant sound(s). This type of array allowed relatively easy access to the juncture word-pairs. The procedure for itemizing the juncture word-pairs consisted of identifying isolated Vowel words and also Consonant(s) plus Vowel words (e.g., “he”) and determining which of these words also became words when a single Terminal consonant was added to the root (e.g., “heat”). The second word of the juncture word-pair was obtained in a similar manner. Vowels and Vowel Consonant(s) which formed words (e.g., “each”) were identified and these words were matched to those words which were also words when an Initial consonant was added (e.g., “teach”). The resultant list of juncture word-pairs (e.g., “he teach” vs “heat each”) allows not only a relatively large selection of pairs of words in which the vowels preceding and following the Juncture consonant are the same, but also word-pairs in which the vowels are different (e.g., “stay teach” vs “state each”). Various aspects of the word list and its possible application are to be discussed.
Simplified Outdoor Vehicle Noise Testing Methods
Authors: Chang Y. M.
Published: October 2005

A way to vary the source to microphone distance and obtain noise measurements over a reflecting plane adhering to the spherical spreading law is achieved by adjusting the microphone height to maintain the ground interference pattern. Vehicle noise radiation mechanisms are re-examined. The study shows how to devise a stationary test procedure which could be expected to correlate with a given passby vehicle noise test procedure. An example shows how a motorcycle passby test is transformed into a correlatable stationary test with five times as short a measurement distance. The noise testing costs and complexity can be significantly reduced by methods discussed here.
Noise measurements on over 20 000 vehicles traveling on Florida roads
Authors: Yost William A.
Published: October 2005

From 1975 to 1977 noise and related data from over 20 000 vehicles traveling on Florida roads were tabulated. The study was conducted by five Florida Universities (University of West Florida, University of Florida, Florida Technological University, University of South Florida, and Florida Atlantic University) in conjunction with the Florida Department of Environmental Regulation. Speed and dBA readings from eight classes of vehicles were obtained according to the measurement provisions of the Florida State Vehicle Noise Law of 1974. There were no significant differences obtained in the dBA readings over time or across the five sets of measurement conditions which existed for the five universities. The 2042 trucks generated an average level of 77.8 dBA with a standard deviation of 4.9 dBA, the 442 motorcycles produced an average of 74.6 dBA with standard deviation of 4.3 dBA and the 18 000 cars, pick-ups, and vans generated on the average 68.1 dBA with a standard deviation of 3.2 dBA. dBA levels were linearly related to speed (mph) for all vehicle classes. These and other statistics will be described.
Acoustical treatment options in a “Third World” auditorium: How many dB per banana tree?
Authors: Blair Christopher N.
Published: October 2005

A large geodesic tent was erected in Grenada to accommodate the 1977 conference of the Organization of American States and subsequently to be used as auditorium facilities. Three weeks before the conference opening and confronted by focused echoes, flutter, and midfrequency reverberation in excess of 5 s, concerned officials decided professional help would be needed. Measurements were made using a combination steady-state and impulsive noise source, viewing the auditorium response with a storage oscilloscope. Transmission qualities of the tent walls led to relatively short low-frequency reverberation times, and calculations accounting for the planned carpeting predicted reasonable mid- and high-frequency reverberation. Island economics and shipping delays mandated using materials readily available on the island for further acoustical treatments. Twenty-six large lightweight panels were constructed of surplus material and hung in a swirling pattern to break up focused ceiling reflections. The flutter echo was destroyed by tilting one of two parallel walls; and banana trees placed around the auditorium perimeter. served to break up focused mid- and high-frequency echoes from the curved sidewalls.
Oceanic fronts and their effects on underwater acoustics
Authors: Mooers Christopher N. K.
Published: October 2005

Oceanic fronts are dynamical phenomena with many properties in common with atmospheric fronts. Fronts are the locus of intense horizontal gradients in one or more properties. Oceanic fronts are generated by atmospheric forcing (momentum, heat, and mass transfer), river runoff, and differential advection and mixing. Mixing is intense in fronts; thus, persistent fronts must be maintained through convergent flows. Typically, fronts have strong thermal and haline gradients. Depending upon the relative signs of these gradients, thermohaline fronts are “density-reinforced fronts” (or, simply “density fronts”) or “density-compensated fronts.” These two classes of fronts differ in their dynamics and, thus, flow fields. Sound speed fronts accompany thermal fronts, which leads to strong acoustic refraction across oceanic fronts. Because of the convergent flow, organic and inorganic particles are concentrated at fronts, leading to aggregation of phytoplankton, zooplankton, fish, and marine mammals and birds. Hence, frontal zones are rich in biological scatterers and noise. The microstructure of fluid velocity, temperature, salinity, and thus, sound velocity is intense in frontal zones, which also enhances volume scattering. Due to gravity wave refraction and breaking by frontal flows, marked sea state variations occur across fronts, producing inhomogeneities in surface scattering and ambient noise.
Experimental verification of a generalized derivative uniaxial shear constitutive relation for the elastomer 3M-467
Authors: Bagley R. L. , Torvik P. J.
Published: October 2005

A generalized derivative (fractional order) uniaxial shear constitutive relation for the elastomer 3M-467 is verified experimentally. The constitutive relation is of the form proposed by Caputo [M. Caputo, J. Acoust. Soc. Am. 60, 634–639 (1976)] and is constructed from data that reflects the frequency dependent stiffness and damping of the elastomer. The constitutive relation is inserted into the equation of motion of a single degree of freedom oscillator which in turn is used to calculate the transform of the acceleration response for impulsive loading. A single degree of freedom oscillator using the elastomer as both spring and damper is constructed in the laboratory. The loading history and the resultant acceleration history are recorded and sampled to calculate the transform using FFT techniques. The experiment is repeated for various values of the mass, spring, and damper in the oscillator. The experimentally produced transforms are compared to those transforms calculated from the equation of motion.