bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of phoneme-tied alternations on the perception of CVC words
Authors: Wilson Richard H. , Arcos John T. , Jones Howard C.
Published: October 2005

Previous studies have shown that the alternation of speech between ears does not affect the recognition performance of normal listeners when nonshadowing response techniques are used. In the present study, phoneme-tied alternation was employed with CVC monosyllabic words. In this signal paradigm, the temporal sequence of the words was maintained with the initial consonant segment presented to one ear, the vowel segment presented to the other ear, and the final consonant presented to the ear that received the initial consonant. The segmentation was accomplished digitally. Psychometric functions on 16 young adult subjects were generated for the segmented materials under monaural (nonalternating) and binaural (alternating) listening conditions. Future testing of patients with auditory dysfunction is planned using the alternated segmented words as a possible test of brain stem integration. [Work supported by VA.]
Frequency-specific data from the FAAF speech identification test
Authors: Haggard Mark , Foster John
Published: October 2005

Can the known selective effects of electronic or physiological distortions upon reception of speech features be used to infer the distortions suffered? At Salt Lake City we described the FAAF test and methodology. By classifying patterns of errors in full symmetrical sets from reference experiments with band-pass filtering in quiet, subscores were defined to quantify use of speech information from low-, mid-, and high-frequency bands. Now we have related subscores to psychoacoustical tuning curve width and to temporal aspects of processing in normal and sensorineural impaired listeners. The correlation of a composite of six high-frequency psychoacoustical measures with the high-frequency band subscore was 0.84, with the low-band subscore 0.53, confirming the frequency specificity of the subscores. Although FAAF subscores might be less efficient than total scores on the specialised tests, the subscore approach combines a usable degree of specificity on several dimenions with the low administrative cost of a single general-purpose test. Applications include diagnostic assessment of mild-moderate impairments and high-quality communication channels.
Discrimination of resonant frequencies of vowel like stimuli
Authors: Gagne Jean-Pierre , Zurek Patrick M.
Published: October 2005

The effects of source function, frequency, and bandwidth on the discriminability of resonant frequencies of synthetic one-formant stimuli were investigated. Two periodic signals approximating glottal waveforms (F0 = 100 Hz; F0 = 250 Hz) and broadband noise were used to excite a voltage-controlled filter whose transfer function resembled that of a formant. The periodic waveforms were generated with either no change in F0, or with a 50-Hz rise and fall in F0. Four resonant frequencies (fr = 300, 475, 650, 800 Hz) and four stimulus bandwidths (Q = 1.0, 2.8, 10.0, 36.0) were investigated. In general, the results show no systematic differences among the DL's obtained with periodic waveforms and the noise source. Also, as expected, the results show that the DL's increase as the fr increases and decreases with increasing Q. For the experimental conditions investigated, the results are well summarized by the following equation: Δfr = 0.079 fr/√Q.
Silence as a phonetic cue: Evidence from a study of duplex perception
Authors: Rakerd B. , Liberman A. M. , Isenberg D.
Published: October 2005

Using a method contrived by Rand [J. Acoust. Soc. Am. 55, 678–680 (1974)], we earlier showed that the transition cues that distinguish [spa] and [sta] can be perceived simultaneously in two phenomenally different ways: as integral parts of those syllables, and as nonspeech chirps [D. Isenberg and A. M. Liberman, J. Acoust. Soc. Am. 65, S79(A) (1979)]. We further showed that although a silent interval (between the fricative noise and the vocalic portion of the syllables) was critical to the perception of the transitions when, on the speech side, they supported identification of the stop consonants ([p] and [t]), it had no measurable effect on the discrimination of those same transitions when, on the nonspeech side, they were heard as chirps. This result was taken to imply that the effect of silence is phonetic rather than auditory. This implication is, however, open to the reservation that different tasks were used on the two sides of the duplex percept: identification for speech, discrimination for nonspeech. The purpose of the present experiment is to speak to that reservation. Accordingly, a discrimination task was used on both sides of the duplex percept. Listeners were presented pairs of stimuli that comprised all combinations of the silence and formant transition cues. They were asked on each trial, to attend to either the speech or the nonspeech and to report their confidence that the members of a pair could be discriminated. The pattern of responses differed markedly for the speech and nonspeech sides of the duplex percept. It indicated that silence greatly affected discrimination of the speech but had little effect on nonspeech. This is taken as further evidence that the perceptual effect of silence as a cue for stop consonants is phonetic (rather than auditory).
Some effects of spectral fusion and spectral-temporal fusion on the perception of /ri-li/ syllables
Authors: Syrdal-Lasky Ann K.
Published: October 2005

The effects of spectral fusion and spectral-temporal fusion of dichotically separated components of single syllables were measured in normal-hearing subjects by identification and discrimination tests. Frequency and amplitude parameters of a synthetic three-formant /ri-li/ continuum varying in initial F3 frequency and transition were constant over all conditions. In one condition, all three formants were presented binaurally; in the spectral fusion condition, F3 and F1F2 were presented dichotically; in the two spectral-temporal fusion conditions, either the initial F3 or the initial F2F3 steady states and transitions were separated dichotically from the remainder of the syllable. Identification and discrimination results indicated shifts in phoneme boundaries and discrimination peaks towards the /li/ category when dichotic presentation released F3 from peripheral masking by lower formants. Slopes of identification functions, reflecting low intrasubject variability and sharpness in phonemic categorization, declined from binaural /ri-li/ to spectrally fused /ri-li/ to spectral-temporally fused conditions. Separate discrimination testing was performed for each of the F3 spectral-temporally fused “duplex” percepts—fused syllable and nonspeech “chirp.” Each duplex discrimination function differed from its binaural counterpart. [Work supported by NSF and NINCDS.]
Context effects on the perception of place of articulation
Authors: Alfonso Peter J.
Published: October 2005

The purpose of the experiment reported here was to determine the effect of phonetic context on the perception of place of articulation. Twelve place continua consisting of C1 VC2 stimuli were synthesized where C1 represented a stimulus taken from a 13-step voiced or voiceless place continuum and C2 represented either /b, d, g, p, t, k/. The 156 stimuli (26 C1 × 6 C2) were randomized and presented to 21 subjects whose task was to label C1. Categorical boundaries were determined for the C1 stimuli and comparisons were made within different C2 place or voice contexts. The results indicated that the perception of place of articulation in C1 systematically varied as a function of place of articulation in C2. A somewhat less systematic C1 boundary shift was observed for C2 voiced-voice-less comparisons. Possible mechanisms accounting for the C1-C2 interaction, articulatory compensation or psychoacoustic effect for example, will be discussed. [Work supported by NICHD NIH-71-2420 and University of Connecticut Research Foundation.]
Development of BSER in kittens: Evidence for different central and peripheral maturation rates
Authors: Walsh E. J. , McGee J. , Javel E.
Published: October 2005

Brainstem evoked responses (BSER) were recorded in 30 kittens from 7 litters. Animals were unanesthetized but restrained. Signals were condensation clicks presented in free field. Latencies and amplitudes of BSER waves I and V were measured at various times during the first 90 postnatal days. Plots of BSER component latencies as a function of postnatal age were computer-fitted by decaying exponentials of the form Y = a + b* exp(−cX). In all kittens, wave I latency attained adult status earlier than wave V. At 90-dB peak SPL, for example, 95% of the adult latency value was achieved at a mean age of 34.4 days for wave I and 38.1 days for wave V. The age-versus-latency plots are not simple offsets of each other, however. Wave I latency shows only a rapid decline to its asymptotic value, but wave V latency shows a rapid decline phase followed by an extended period of slow decline. The data support the notion that maturation of central auditory responses is not explained entirely by maturation of the cochlea and auditory nerve.
Brainstem evoked response waveforms for high-, middle-, and low-frequency bands derived without the use of masking
Authors: Gerken George M. , Helfer Thomas M.
Published: October 2005

The scalp recorded waveform (W) evoked by a brief acoustic stimulus is considered to be the algebraic sum of waveforms produced by activity originating in the various regions of the cochlea. The waveform produced by a middle-frequency stimulus (Wm), for example, can be considered to be composed of regional responses from high- (Rh), middle- (Rm) and low- (Rt) frequency areas of the cochlea. In addition, from the spectrum of a middle-frequency stimulus, the relative strengths of the high-, middle-, and low-frequency components of that stimulus can be determined so that each W and R term is identified with a specific intensity: Thus Wm(Im) = Rh(Ih1) + Rm(Im) + Rt(It). Similar equations exist for stimuli of other frequencies and intensities. Individual R waveforms can be derived from sets of W waveforms by an algebraic method of successive substitutions. Examples are presented of derived waveforms and clinical implications are discussed.
Automotive vibration isolation using optimization techniques
Authors: Bennett James A.
Published: October 2005

Optimization techniques allow the engineer to specify a required performance level for a dynamic system, and then the optimization will select the values of a predetermined set of design variables to accomplish these goals. In the early stages of the design process, these goals may be described in terms of desired frequency ranges or ordering of mode shapes. Two techniques for accomplishing these goals will be presented. In the later stages of the design, when a more detailed model is available, it is more advantageous to develop methods which minimize the response of the structure over a range of frequencies. The response is usually due to some typical frequency-dependent input. These techniques are currently in use in the automotive industry to improve ride isolation.
Ensemble averages of power flow in randomly excited coupled beams
Authors: Davies H. G. , Wahab M. A. , Khandoker S. I.
Published: October 2005

This paper considers the transmission of transverse vibrational energy between two coupled beams subjected to random excitation. Both distributed and point excitation is considered. Extensive numerical results are given for the frequency decomposition of power flow between the beams. The power flow is a function of the nondimensional parameters describing frequency, length ratio of the two beams, damping, and position of the excitation point. Single frequency and octave band averages are shown for various values of the length ratio, and means and variances are calculated for length ratios between one and two. Various approximate results based on modal analysis and on SEA are compared with the exact results.
Tuning and temperament of the clavichord: or what effect does the vibrato and bebung have on affective tuning of this percussive stringed instrument?
Authors: Mulder George W.
Published: October 2005

Though the clavichord is the only fixed pitch instrument of the percussive string type that permits a variability in pitch through an affective modification or vibrato derived from the movement of the tangent on the string, the resulting pitch variations appear to be aesthetic oriented rather than scientific temperament related. However, in surveying the treatises on clavichord practice, matters of pitch variants and resultant temperament modification come to bear. To what degree may the tuning and temperament of the clavichord be modified through the practice of vibratory motion in pitch?
Acoustical parameters for violin and viola back wood
Authors: Hutchins Morton A.
Published: October 2005

Ten different kinds of wood with parameters thought to be within the range suitable for viola back plates have been built into ten 16-in. violas. Sample test strips were cut from each piece of wood in both the crossgrain and longitudinal grain orientations, and the strips tested acoustically in their fundamental mode giving information on velocity of sound, density, damping, log decrement, and Young's modulus. These parameters will be presented and discussed in relation to those of woods for violin backs as tested by Haines and by Barducci and Pasqualini.
Errors in workplace noise measurement
Authors: Eldred Kenneth McK.
Published: October 2005

There are many types of errors inherent in workplace noise measurement. They result from limitations of both the measurement instrument and the measurement procedure with respect to the spatial and temporal properties of the sound field in the vicinity of the worker. These errors can increase the cost of compliance with workplace noise standards and/or reduce the protection of the workers, depending on the nature and direction of the total error. This paper explores the potential magnitude and causes of some of the most significant errors, and proposes ways in which they might be reduced in the future.
Propagation of nonlinear acoustic waves in a stratified atmosphere
Authors: Crighton D. G. , Lee-Bapty I.
Published: October 2005

We derive a generalized Burgers equation for the propagation of spherical nonlinear waves in a viscous atmosphere with constant temperature and exponential density stratification. The wave evolution is calculated, mostly in analytic form, to arbitrarily large distances above and below the horizontal, from data prescribed at some initial radius. The method used is asymptotic and based on small values of the ground level viscosity, but includes effects of weak nonlinearity, spherical spreading, and exponential variation of the kinematic viscosity. For sinusoidal initial data, shocks always form above the horizontal; the shocks thicken with altitude, and the whole wave motion is ultimately governed by the “cylindrical Burgers equation.” A criterion is given for the portion of the wavefront below the horizontal in which shocks form; here the shocks become ever thinner with increasing depth, and cannot remain of the familiar steadily progressing Taylor form. Instead, the shocks continue to evolve with range, in a manner governed by a partial differential equation which is derived and investigated numerically. [Work supported by Science Research Council, United Kingdom.]
Angular response of ceramic and polymer ultrasonic hydrophones
Authors: Shombert David G. , Smith Stephen W.
Published: October 2005

The response of miniature ultrasonic hydrophones was measured in the receive mode for angles of incidence ranging from 0° to 90°, at frequencies of 2.5, 3.5, and 5.0 MHz. Ceramic (PZT) hydrophones of 0.635-mm diameter were observed to have a mainlobe angular width substantially less than that predicted by diffraction theory. They also exhibited significant response at large angles of incidence; in some cases, the response at 90° was comparable to the response at normal incidence. The response of polymer (PVDF) hydrophones of 1-mm diameter was also measured at the above three frequencies, and was closer to the predicted behavior. The angular response of the polymer hydrophones was also determined at a frequency of 511 kHz, and these data support the recent prediction [A. R. Selfridge, G. S. Kino, and B. F. Khuri-Yakub, Appl. Phys. Lett. 37, 35–36 (1980)] that the directivity function of a transducer that is not surrounded by an infinite rigid baffle must be modified by an additional term.
Through ice echo sounding for Arctic hydrography
Authors: White Bryan F.
Published: October 2005

The requirements for hydrographic surveys in the Arctic exceed the capabilities of conventional technology based on ships and launches as operational platforms. Experience with echo sounding through ice now spans twenty years. Recent developments have led to systems based on helicopters and tracked vehicles that are effective. A multi-layer model for the ice, skeletal layer, water system for a small aperture transducer pressed into the snow and ice surface predicts a radiation impedance with significant periodic variation in amplitude and phase with both frequency, and layer thickness. A sounding system incorporating a specially designed transducer, transducer actuators, and a conventional echo sounder modified to permit transmit frequency adjustment is described. The system is used routinely to sound depth of 20 to 400 m. Coupling of conventional sounder transducers to a prepared ice surface using oil permits sounding to 4 km depths.
Shock formation and spectrum alteration in spherically diverging finite amplitude waves
Authors: McDaniel Oliver H. , Welz Joseph P.
Published: October 2005

It has been suggested that the characteristic farfield spectrum of a supersonic jet could be the result of nonlinear acoustic phenomena. Evidence from previous studies indicate that this may be the case; however, sound power levels comparable to those generated by an actual supersonic jet were not obtained. In this study, a 10 000-W acoustic source was installed in an anechoic chamber. Band limited random noise and dual frequency pure tones were generated. Spectrum alteration as a function of propagation distance and acoustic shock formation were observed for both cases. For the band limited random noise case, a continuous high-frequency spectrum with a shape inversely proportional to frequency was obtained in the farfield regardless of the initial spectrum shape. For dual frequency pure tone excitation a strong parametric effect was observed with sum and difference frequency components comparable in level to those of the primary frequencies. [Work supported by NASA Langley Research Center.]
High-intensity sound propagation in bulk porous materials
Authors: Kuntz H. L. , Blackstock D. T. , Perreira N. D.
Published: October 2005

The acoustical properties of bulk porous materials change with the sound intensity. Previous high-intensity sound studies have dealt with the impedance of sheet materials (W. E. Zorumski and T. L. Parrot, NASA TN D-6196). Low- and high-intensity sound measurements were made on batted Kevlar 29, felted Kevlar, and an acoustical foam. The low-intensity measurements showed agreement with predictions based on small-signal theory [A. H. Hersh and B. W. Walker, AIAA Paper No. 80-0986, 6th Aeroacoustics Conference, 4–6 June (1980)]; both the phase speed and attenuation increased with frequency in the 100 Hz to 10 kHz range. In the high-intensity tests, 4-ms tone bursts of 1, 2, and 3 kHz were sent through the materials. The waveform and spectrum of each pulse were measured at two microphone positions, and the measurements were used to determine the attenuation of the fundamental and higher harmonic components. The experimental results show excess attenuation of the fundamental and the generation of higher harmonic components. [Work supported by NASA-Lewis Research Center and Office of Naval Research.]
Quadrupole projection of the radiation stress: Explanation of the nonvanishing long-wavelength limit
Authors: Marston Philip L.
Published: October 2005

The deformation of nearly spherical drops or bubbles due to second-order stresses is proportional to spherical harmonic projections p̂lmr of those stresses. [P. L. Marston, J. Acoust. Soc. Am. 67, 15–26 (1980), Eq. (27).] The radially outward acoustic radiation stress is expessed as a series of p̂lmrYlm where the Ylm are orthonormal spherical harmonic functions of the polar and azimuthal angles, θ and φ of the location on the drop's surface. For a plane standing wave with a peak first-order pressure ps and wavenumber k = ω/c, direct computation of the quadrupole (l = 2, m = 0) projection gives, when kR ≪,1 and f ≠ 0, p̂20r ≃ −3ps2(5 π)1/2 × (λ − 1)2f2/5(1 + 2λ)2ρ0c2, where R is the drop's radius, c is the sound speed in the outer fluid, λ ≡ ρ1/ρ0 is the ratio of inner to outer fluid densities, f = sinkh, and h is the distance of the drop's center from a velocity mode. When ρi ≠ ρ0, p̂20r and the flattening of the drop do not vanish in the long-wavelength (kR = 0) limit. This result also follows from the θ dependence of the Bernoulli pressure for incompressible potential flow past a sphere. Setting f = 1, this limit applies to traveling waves; it is also useful for bubbles providing (kR)2 ≪ λ ≪ 1. [Work supported by ONR. P. Marston is an Alfred P. Sloan Research Fellow.]
Bulk cavitation closure pulses
Authors: Clark J. A.
Published: October 2005

Waterborne shock waves reflecting at a free surface can produce large regions of cavitating water near the surface. This type of cavitation, known as bulk cavitation, tends to collapse again so rapidly that a second shock (called a closure pulse) is produced which can be as strong as the initial shock. This process can also be interpreted as delayed reflection of the incident shock wave, or as absorption and reradiation of the wave by the surface. Theoretical studies will be described which used both finite-difference and finite-element computational methods to analyze this phenomenon. Some results will be compared with at-sea tests and laboratory experiments. [Research supported by ONR.]
Cross-language study of children's prosodic development—I: Description of the data set
Authors: Allen George D.
Published: October 2005

A study has been initiated comparing the prosodic development of 2- through 5-year-old Austrian, French, and Swedish children. Three girls and three boys at each of four age levels (2, 3, 4, and 5 years) were tape recorded in Salzburg, Aix-en-Provence, and Stockholm, once in autumn, 1979, and then again six months later. The 2 year olds named pictures chosen for their polysyllabic structure and comparable segmental composition between languages (e.g., elephant). The 3 year olds conversed with an assistant in a slightly constrained situation until an adequate speech sample had been obtained. The 4 and 5 year olds, in addition to conversing with the assistant, played a rhythmic naming game (the TAKI task). All recordings were stereo, to aid subsequent perceptual analysis, and great attention was paid to the resulting acoustic quality. Analyses are presently under way, and findings of interest will be reported. [Supported by NSF and The University of North Carolina.]
F0 rule for discourse
Authors: Umeda N.
Published: October 2005

Rules for the fundamental frequency (F0) contour for discourse have been formulated. The rules are based on F0 data that consider boundaries and segmental factors in a number of natural readings. The rules give F0 within a word according to stress and boundary values, and a concatenation rule is applied to obtain the continuous F0 across two adjacent words. The rules have been tested on a naturally read story using an LPC vocoder synthesis. A demonstration tape will be played.
Prosodic aspects of American English speech rhythm
Authors: Nakatani Lloyd H. , O'Connor Kathleen D. , Aston Carletta H.
Published: October 2005

We studied American English speech rhythm using reiterant speech with the prosody of normal speech but without its segmental variations. Syllable duration was strongly influenced by stress and by word and phrase boundaries, but negligibly by other nonfinal positions within words and phrases. Word duration increased linearly with word size, and varied with stress pattern for words of constant size. Metrical foot duration increased approximately linearly with foot size. Feet of the same type and size were of constant duration.
The search for a structural basis of temporary threshold shift: Some old and new ideas about hair cell fatigue
Authors: Saunders James C.
Published: October 2005

A number of observations have been made about changes in hair cell structure after noise exposure which causes a temporary hearing loss. These include a proliferation in the subsurface cistern of the endoplasmic reticulum, changes in membrane permeability on the reticular lamina, swelling of the intracellular compartment, decoupling of the stereocilia—tectorial membrane attachment in outer hair cells, the fusion of stereocilia, and the loss of stereocilia rigidity. Recent evidence suggests that this latter observation may be important. The actin filaments contained within the stereocilia are packed with paracrystalline order. Evidence will be presented to show that the macromolecular bridges between actin filaments appear to be damaged by noise. Loss of these crossbridges might reduce stereocilia rigidity and mechanically decouple the hair cell from its driving force. The possibility that stereocilia may regain their paracrystalline order, and thus their rigidity, during post-exposure recovery will be considered. [Supported in part by the Deafness Research Foundation.]
Theory versus practice in the use of absorptive draperies for variable reverberation time in auditoria
Authors: Schultz Theodore J.
Published: October 2005

At the Acoustical Society meetings in Atlanta last year, a design scheme and design curves were presented that were intended to permit the selection of drapery fabric conforming to desired sound absorption characteristics, according to a theory developed for that purpose. [See J. Acoust. Soc. Am. Suppl. 1 67, S83 (1980).] It was expected that this scheme would provide a firm basis for design of variable reverberation time in auditoria. It was mentioned at that time that certain discrepancies can occur between absorption measurements for the same fabric carried out in laboratory reverberation rooms and in concert halls. The present paper reports further practical experience with the use of such draperies. In particular, it discusses the “diminishing return” to be expected as more and more fabric is added to the room and compares the effect of hanging the fabric either parallel to the wall, perpendicular to the wall or “free in space.” Special reference is made to recent measurements in Louise M. Davies Symphony Hall in San Francisco.
Variable reverberation and speech intelligibility
Authors: McKay Ronald L.
Published: October 2005

Information will be presented on two multipurpose auditoria, each of approximately 1200 seats and each employing operable velour curtains to vary reverberation times and sound-reflection patterns. The first hall's mid-frequency reverberation-time range lies between about 1.0 and 1.5 s; the second hall's range lies between about 1.5 and 2.0 s. The presentation will include photographs, physical information, measured reverberation times, and results of word articulation tests—with and without sound system.
Variable acoustics for multi-use halls using electronic reflected energy systems
Authors: Jaffe Christopher
Published: October 2005

The classic problems of the multi-use hall physically designed to meet symphonic performance criteria, are the extended times and high sound pressure levels of the reflective field. Bolt Beranek & Newman, Inc. and George Izenour pioneered the concepts of variable physical acoustic characteristics in hall design, by moving room ceilings to reduce volume and introducing variable absorption in the form of tracked drapery and banners. The philosophy of this approach, is to design the room for natural symphonic conditions, and vary the acoustics for opera and amplified musical theater and popular programs. Concurrently, Parkin, Veneklasen, and others were working on the premise of designing a room with short reverberation times for opera and amplified programs and extended the reflections required for symphonic performance electronically. In 1971 Jaffe, on the basis of the psycho-acoustic research of Beranek and Schultz began to develop electronic systems simulating specific bits of reflective energy critical to the perceptions of presence, definition, and warmth. This paper describes the systems developed, measured results, and the response of the musical community to the use of electronics to provide reflective energy.
Acoustics in telecommunication: An overview
Authors: Wojcik J. J.
Published: October 2005

Various scenarios in voice communications are discussed to identify pertinent acoustic and electroacoustic parameters which impact the transfer of information. Face-to-face mode of communication is influenced by acoustic environment. Physical separation of speaker-listener (distance, mechanical obstacles) introduces acoustic functions impairing communication. These impairments can be compensated by electronic aids with characteristics inverse to those creating impairments. The telephone network is one of the classical examples of electrical compensation of losses in the situation where the source and receiver of information are physically separated. Imperfections of the compensating chain are, in many situations, used to the advantage of communicating parties. Inconvenience of the handset versus privacy, lack of visual contact, bandwidth versus nonlinearity versus noise, amplitude characteristics versus intelligibility, are a few of many examples illustrating the need for continuous adjustment of electroacoustic requirements rather than research for reproduction of the “face-to-face” mode. Digital transmission of voice, data transmission parallel to voice communication are adding, new problems when electroacoustic characteristics of the network are to be determined. New economic and technological trends are leading to the introduction of new electroacoustic systems complementing the classical “person-to-person” voice communication: Speaker or listener can be replaced with synthetic speech or voice recognizing machines, respectively, conferencing groups linked via telephone network, etc.
Telephone speech quality and intelligibility in noisy environments
Authors: Silbiger Herman R.
Published: October 2005

Telephone listening often takes place in high ambient noise environments. Listening tests were performed on the relationship between intelligibility and quality, and received speech level and line noise level, over a wide range of ambient noise levels. Intelligibility is usually shown as a function of the signal-to-noise ratio. In listening over the telephone three sources of noise can be identified that affect the acoustic signal-to-noise ratio. These are line noise, room noise entering the ear acoustically via the leakage path between the receiver cap and the pinna, and noise picked up by the transmitter and mixed with the speech electrically via the sidetone network. Speech intelligibility and quality tests were performed with received line noise levels from 30 to 72 dB(A) and speech levels of 68 and 84 dB(A). Ambient noise levels ranged from 55 to 82 dB(A). Intelligibility was measured using the Modified Rhyme Test, and quality was measured on a five point scale. For all conditions sound levels were measured at the eardrum using KEMAR. The results of these tests show that the relationship between intelligibility, quality, and signal-to-noise ratio can best be predicted when all sources of noise are taken into account and measured at a single location.
Simulated speech signal and its use in voice transmission measurements
Authors: Chytil M. , Niedzwiecki A.
Published: October 2005

A laboratory prototype of a generator producing a signal which approximates the long term average spectrum, instantaneous amplitude distribution, and syllabic structure of speech is described. Results of preliminary measurements of transmitting sensitivity/frequency responses and objective loudness ratings on six telephone sets with carbon transmitters using this signal indicate better agreement with results obtained with real voice than results of previous measurements done with sinusoidal and pseudo-random signals.
Utilization of the tri-word configuration of the Modified Rhyme Test (TMRT) to evaluate speech commuications equipment and hearing for speech
Authors: Williams C. E. , Mosko J. D. , Thomas G. B. , Maxwell D. W.
Published: October 2005

In 1975 the two senior authors, together with J. W. Greene, published data showing little difference in overall listener performance for single, double, and triple word test item configurations from the six monosyllabic word lists of the Modified Rhyme Test (MRT), a multiple choice intelligibility test. Subsequently, the tri-word configuration (TMRT) has been utilized in laboratory evaluations of speech communications equipment and the ability of individuals to hear speech in noise. Data reflecting the versatility and potential of the TMRT for such evaluations are presented. Included among the data are TMRT performance scores and pure tone hearing levels for selected age groups. [Work sponsored by the Naval Medical Research and Development Command.]
High-performance craft noise reduction
Authors: Thomson Donald C.
Published: October 2005

The airborne noise level criteria specified in contracts for the construction of U.S. Navy surface boats and craft are briefly reviewed. Airborne noise levels measured aboard hydrofoil craft, planing craft, and air cushion vehicles are compared with habitability, deafness risk, and personnel communication noise criteria. The acoustical features of several small craft and the effectiveness in reducing noise levels are discussed. It was determined that airborne noise criteria that are specified in the construction of large surface ships are not practical to the smaller craft.
Dosimeter response to impulsive noise
Authors: Kamperman George W.
Published: October 2005

Noise dosimeters read high on impulsive type noise—and they should. It is not possible for a simple dosimeter to correctly compute the noise dose using a 5-dB exchange rate, for noises that vary in level at intervals less than 10 s. The 1-s RC time constant averaging circuit, in the OSHA type dosimeter, working in conjunction with the 5-dB exchange rate circuit causes the effective exchange rate to approach 3 dB as the impulse duration becomes shorter. The noise environment in a typical metal fabricating facility will cause a dosimeter to read between 5 and 13 dB too high (2–6 times expected dose) relative to the OSHA 5-dB exchange rate. With the preponderance of evidence in support of the 3-dB exchange rate for evaluating damage risk to hearing, especially for impulse noise, it may be fortuitous that the OSHA type dosimeter has a 5–3-dB hybrid exchange rate. An immediate problem is the poor transient response of most dosimeter models because there are not dosimeter performance standards on impulse response characteristics.
Some factors affecting noise dosimeter response
Authors: Dotti Norman R. , Goldman Howard J.
Published: October 2005

The accuracy of noise dosimeter measurements has been questioned for a number of years. The questions are of importance not only for technical reasons but also because legally binding decisions may be based on these measurements. The effect of impulsive noise on total dose is shown mathematically to be potentially quite substantial; several dBA more than the tolerance allowed by OSHA procedures. ANSI S1.25 allows a dosimeter to accumulate a noise dose down to 87 dBA, while the OSHA regulation does not recognize dose contribution below 90 dBA. The ANSI S1.4 definition of “slow” response allows a variation of 4 dBA (within “2 to 6 decibels less” than “a steady signal”). When accumulating dose with other than a 3-dBA exchange rate this variation effects the total dose determination.
Application of in-ear dosimetry to the measurement of the noise exposure of Transport Canada radio operations personnel
Authors: Hall Gordon D. , Elcombe David , Forshaw Stan , Cruchley Jane , Ruden Jerry
Published: October 2005

A comprehensive in-ear noise dosimetry program has been performed on Radio Operations personnel. The noise exposure of 26 subjects was measured during normal work shifts over a period of about two weeks; mean subject noise exposures were calculated and compared to existing criteria. A total of 208 individual measurements were performed at Gander Aeradio, and at the Halifax and Vancouver Coast Guard Marine Radio stations. A miniature microphone was located in the cavum of the concha, allowing assessment of the combined contribution of both room and headset generated noise. An equalization network between the microphone and dosimeter approximated the frequency-dependent pressure transformation required to equate in-ear measured levels to free field conditions. Individual subject Leg's ranging from 73 to 100 dBA were noted. Pre/post shift audiometry was performed and is briefly summarized. The effect on measured levels of traffic, atmospheric, and operating conditions is discussed to form a background upon which mitigating measures can be based. Specific recommendations for acoustical treatment and proposals for modifications to radio equipment are discussed.
The incorporation of digital noise correction into an environmental noise monitor
Authors: Coulter J. E. , Hardenbergh H. W.
Published: October 2005

Digital Noise Correction as applied to sound level measurement is based on adjusting the sound level readings to account for the instrument's electronic noise floor. DNC's application to a digital environmental noise monitor has lowered by 10 dB, the sound levels at which ±1-dB accuracy measurements can be taken. This paper details the manner in which DNC has been implemented in a commercially available instrument to account for instrument to instrument variation in electronic noise and to compensate for noise floor drift with temperature.
On feasibility of using multimode optical fibers in optical hydrophones
Authors: Shajenko Peter
Published: October 2005

The use of multimode optical fibers with an interferometer for measurement of small displacements is presented. In the experiment using an optical fiber 1 km in length, a displacement of 4 × 10−3 Å was measured. The measured value was limited by ambient noise in the laboratory. In a conceptual optical hydrophone design, such a displacement would correspond to a minimum detectable pressure of 65 dB//1μPa. In shot-noise limited operation the minimum detectable pressure would be 44 dB//1μPa. This value is comparable with the value obtainable with good quality piezoelectric hydrophones. [Work supported by NUSC.]
Threshold effects in time-delay estimation via cross-correlation
Authors: Ianniello J. P.
Published: October 2005

The estimate of the difference in time of arrival of a common signal received at two sensors, each of which also receives uncorrelated noise, is shown to exhibit a thresholding effect similar to that in pulse position modulation. Thus, as the post detection signal-to-noise ratio decreases, the probability of an anomalous estimate (an estimate that is outside ±Tc/2, where Tc is the correlation time of the process) increases suddenly and precipitously. Theoretical results for the probability of an anomalous estimate are presented and verified experimentally. Threshold is shown to depend most strongly on the two quantities M and B. M = 2T0/Tc, where ±T0 is the extent of the cross-correlation function searched for a peak; M is thus the effective number of independent correlation bins. B = (BST)1/2{(S/N)/[(S/N)2 + 2(1 + S/N)2]1/2} where BS is the statistical bandwidth of the process, T is the total observation time, and S/N is the signal-to-noise ratio at the sensors. Depending on M, threshold is shown to occur in the region 3 < B < 5. [Work supported by NAVSEA.]
A PASCAL language facility for the design and analysis of acoustic line arrays
Authors: Greene David C. , Parris Paul E.
Published: October 2005

A PASCAL language facility for the design and analysis of acoustic line arrays is described and sample outputs of the facility are presented. The facility consists of two types of programs. The first type is used for designing arrays (e.g., generating element positions and shading coefficients) and the second type is used for analyzing the performance (e.g., array gain, side-lobe levels) of the designs generated. Flexibility is maintained by leaving the programs intact and introducing all changes for new cases via input textfiles. Outputs available are automatic plots of universal beam pattern functions, polar directivity patterns, directivity index as a function of beam steer angle or frequency and array gain as a function of beam steer angle in a directional noise field.
The forward and backward projection of acoustic fields using FFT methods
Authors: Benjamin Kim C. , Stepanishen Peter R.
Published: October 2005

The forward and backward propagation of harmonic acoustic fields using Fourier transform methods is presented. In particular, the forward propagation of a velocity distribution to obtain a pressure field and the backward propagation of a pressure field to obtain a velocity distribution are addressed. Numerical examples are presented to illustrate the nearfield behavior of the pressure field from complex planar vibrators, e.g.,—an ultrasonic transducer or plate, with nonuniform velocity distributions. The numerical results, which were obtained via the use of FFT algorithms, are presented for vibrators which are operating above and below coincidence. These results illustrate the acoustic nearfield as a function of distance from the vibrator. Numerical results are also presented to illustrate the backward projection method. The pressure field of a 3 × 3 focused array is back projected to obtain the velocity distribution for several cases of interest. These results illustrate the utility of the transform method and the effect of spatial windows or filters in its implementation using FFT algorithms. Finally, the use of the Fourier transform method is shown to provide a rapid means of obtaining the radiation impedance or radiated power from a complex vibrator. As an example, the radiated power from an ultrasonic transducer with a uniform velocity over a square aperture, is obtained via the use of FFT methods and compared to earlier results. [Work supported by NIH.]
Signal detection with superdirective circular arrays operating in isotropic noise
Authors: Wilmut Michael J. , MacKinnon Robert F.
Published: October 2005

The Fourier-Bessel transformation of spatial data from a circular array is used as a basis for the study of the characteristics of super-directive circular arrays operating in isotropic noise. The resulting transform variables, known as kth order circle processes, are used to calculate the array gain of such an array. For the case of planewave signals with wavelength much larger than the radius of the array, the detection performance of nondirectional parametric and nonparametric detectors can be determined analytically.
Coherence measurements of boundary reflected signals
Authors: Rowlands R. O.
Published: October 2005

Using data recorded by NUSC in July 1977 during the RAPLOC multipath sea test, correlation measurements were made between the transmitted and received signals. The range was of the order of 33 kyd and ray-path calculations indicated that there were four distinct paths between the transmitter and receiver. In increasing order of travel times, these corresponded to rays that were reflected from the bottom; the surface, then the bottom; the bottom, then surface; and finally, the surface-bottom-surface. The number of paths that produced distinguishable peaks in the correlogram varied from, at least one, 100% of the time, to all four, 24% of the time. Graphs are also presented showing how the magnitude of a correlation peak fluctuates in sympathy with the amplitude of the received signal. [Work supported by NUSC, New London.]
High data rate acoustic telemetry
Authors: Gordon Alan , Mackelburg Gerald R. , Watson Stanley J. , Castile Brett D.
Published: October 2005

Four separate acoustic telemetry experiments were conducted during 1979 and 1980 off eastern San Clemente Island in water 1350 to 1450 m deep. In each experiment, telemetry originating near the seafloor was transmitted to receivers aboard a drifting surface ship which remained within 45° from vertically above the telemetry source. Projector and receiver full beamwidths ranged from 40° to 80°. Telemetry formats used were 128 line, 7700 bit/second (b/s) video; 256 line, 11 500 b/s video; 2400 b/s pseudorandom differential quad phase shift keying (DQPSK) and 4800 b/s DQPSK. The first three formats were simultaneously modulated on 8- and 40-kHz carriers while the latter occupied the 8–14-kHz band. Two millisecond pings and cw transmissions were interspersed with the telemetry to provide for acoustic channel monitoring. Video received during nearly vertical transmissions was subjectively free of acoustically induced defects. At angles less than 15°, 1.4 × 107 bits were transmitted error free at 4800 b/s, indicating an underlying error rate ⩽2.14 × 10−7 at the 95% level of confidence. Greater error rates and poorer video, due to beam pattern and power limitations, were observed at larger angles.
The lateralization of carrier-delayed and modulation-delayed pulse-modulated signals
Authors: Shelton Brian R. , Green David M. , Hafter Ervin R.
Published: October 2005

An anomalous result has been reported in the lateralization of pulse-modulated signals presented with a modulation delay: For a fixed interaural modulation delay the spatial position of the binaural image varies with the carrier frequency, and for some carrier frequencies the image is heard to be closer to the ear presented with the delayed modulation waveform. A cross-correlation model has been proposed to account for these results [Hafter, Shelton, and Green, J. Acoust, Soc. Am. 68, S16 (1980)]. The lateralization of pulse-modulated signals presented with an interaural carrier delay is reported here. The data do not contain “illusory” results, that is, the binaural image is always heard closer to the ear presented with a carrier advance. However, variations in performance as a function of carrier frequency correspond to the dependency of modulation-delay performance on carrier frequency. The assumption that a cross-correlation process is involved in the binaural analysis of both modulation delay and carrier delay provides a means of predicting the carrier-delay performance from the modulation-delay data. The model provides a good prediction of carrier-delay lateralization.
Binaural hearing with a bilateral, high-frequency loss
Authors: Gabriel Kaigham J. , Colburn H. Steven
Published: October 2005

Results from four binaural experiments are presented for subjects with bilateral, high-frequency hearing losses. The experiments are interaural time discrimination, interaural amplitude discrimination, interaural correlation discrimination, and binaural detection of tones masked by noise. The stimuli are third-octave noises and tones at six different center frequencies. Preliminary data with noise at a center frequency in the normal range (500 Hz) and at a center frequency in the loss range (3 kHz) of the audiogram show abnormal performance for all tests, at both frequencies. Specifically, reduced MLDs (∼6 dB), increased interaural correlation jnds (∼0.25 from a reference correlation of 1 and ∼0.7 from a reference correlation of 0), increased interaural amplitude jnds (∼3 dB), and increased interaural time jnds (⩾60 μs). [Work supported by NIH.]