bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioral and cochlear responses in C57BL/6J mice primed at various ages for audiogenic seizures
Authors: Saunders J. C. , Hirsch K. A.
Published: October 2005

Groups of mice were primed for audiogenic seizures when 14, 18, 28, 38, and 58 days old by exposing them to a one-octave band of noise (8.0–16.0 kHz) at 110 dB for 2 min. Five days later some of these mice were tested for audiogenic seizure behavior by re-exposing them to the priming stimulus. The cochlear responses of other primed mice were also examined and compared with similar data obtained in unprimed control animals. Seizure behavior was only observed in the group primed when 18 days old. Similarly, priming in this group produced a severe loss in cochlear function. Priming on day 14 or 58 had little effect on the cochlear responses. These data are considered in terms of auditory development and the susceptibility of young organisms to acoustic (noise) trauma. [Supported by a grant from the Deafness Research Foundation.]
Adaptation in the noctuid acoustic receptor
Authors: Adams William B. , Belcher Edward O.
Published: October 2005

Two adaptation processes are observed in the spike response of the noctuid acoustic receptor: a short-term process with a duration of approximately 20 msec and a long-term process with a duration of 2 sec. The short-term process is also observed in recordings of the receptor potential, but the long-term process is absent, indicating that long-term adaptation has its origin in the spike-generating mechanism.
Parameter selection criteria for parametric receivers
Authors: Goldsberry Tommy G.
Published: October 2005

Selection of parameters for a parametric acoustic receiver is complicated by the fact that the basic parameters are not independent. The parametric receiver is an active device; hence, there is a self-noise contribution to the output which is a function of the selected parameter values. A systematic procedure has been developed for selecting optimum values of these parameters by minimizing the total self-noise output of the parametric receiver. Equations were derived that define the impact on self-noise of the basic parameters that are not independent. These equations were evaluated to obtain optimum parameter values for specified sets of boundary conditions. The results of this analysis and examples of the parameter selection procedures are presented and discussed.
Empirical results from frequency-scanning nonlinear sonar in deep water
Authors: Birken John A.
Published: October 2005

The wide-bandwidth capability of nonlinear sonar allows conduction of ocean bottom and sub-bottom investigations at many frequencies. In order to obtain a wide-bandwidth ocean bottom signature spectrum, a system has been implemented which serially translates a coherent frequency source to five different channels, f + Δf, f + 2Δf, f + 3Δf, f + 4Δf, and f + 5Δf. In the ocean, the nonlinear mechanism convolves a second selected primary frequency f with each appearing channel. The low sonar frequencies Δf, …, 5Δf efficiently propagate to large ocean depths. The returning signals provide an ocean bottom and sub-bottom frequency spectrum. Theoretical predictions were presented in the paper “Frequency Scanning Nonlinear Sonar Performance Modeling,” by John A. Birken at the Ocean '74 Conference. In March 1974, William Konrad, NUSC/NL, successfully demonstrated his 0.8-m2-aperture nonlinear array. His empirical data, which were recorded on tapes, provide a source of empirical information to compare with the performance model. Sub-bottom predictions versus frequency have been found to agree significantly with the collected data.
TOPS, a very high-power parametric source
Authors: Konrad W. L. , Carlton L. F.
Published: October 2005

A high-powered parametric radiator system referred to as a TOwed Parametric Source has been developed and given initial tests. This source is capable of developing difference frequency source levels near 225 dB/μPam at 5 kHz with a power input of 80 kW. Source levels usable in several applications can be produced at frequencies extending to as low as 50 Hz. The results of a sea test measuring its performance in bottom and sub-bottom sounding over a wide frequency range is presented. [This work was supported by the Naval Ship Systems Command.]
Improved efficiency of an acoustic parametric source
Authors: Eller Anthony I.
Published: October 2005

In the customary design of an acoustic parametric source, a primary signal consisting of two high–frequency wave components is projected into the water. Because of the inherent nonlinearity of acoustic propagation, the two primary components mix to form a wave at the difference frequency. This paper describes how one can increase the parametric conversion of energy into the difference–frequency beam through the use of primary signals other than the two–component signal described above. For example, another primary signal one might use consists of a sinusoidal carrier wave undergoing amplitude modulation. Use of such an AM primary signal, with 100% modulation, leads to a predicted difference–frequency pressure amplitude that is 2.5 dB greater than the corresponding amplitude obtained with a two–component primary signal of the same total input power. This prediction shows approximate agreement with a measured increase of 2.1 dB. For a primary signal consisting of N components, theory predicts an increase in difference–frequency level that approaches 6 dB as an upper limit.
Propagation of plane sound waves of finite amplitude in inhomogeneous fluids
Authors: Carlton T. W. , Blackstock D. T.
Published: October 2005

The problem of propagation of finite–amplitude waves in an inhomogeneous medium may be approached by considering the effect of inhomogeneity on the wavelet propagation speed c0 + βu. For a homogeneous medium this speech is constant. For an inhomogeneous medium, however, the speed varies because (1) the sound speed c0 generally varies, (2) the particle velocity u varies because of the changing impedance ρ0c0 of the medium, and (3) the coefficient β, which includes the parameter B/A characterizing the nonlinearity of the pressure-density relation, may vary. For gases β = (γ + 1)/2, which is a constant because γ, the ratio of specific heats, is constant over a wide range of conditions. In the ocean, however, β varies because B/A depends on pressure, temperature, and salinity. It turns out that the solution for plane waves in an inhomogeneous medium is obtained by replacing x (distortion distance) and u in the solution for a homogeneous medium by the functions z = ∫(β/β̄)(c̄0/c0)5/2(ρ̄0/ρ0)1/2dx and w = (ρ̄0c0/ρ̄0c̄0)1/2u respectively. The overbar indicates a value at the starting point. Examples treated include the atmosphere and the ocean. [Work supported by ONR.]
Temporal-order discrimination in nonspeech sequences presented to the left or the right ear
Authors: Divenyi P. L. , Danner W. F.
Published: October 2005

Three right-handed, naive listeners with normal hearing had to discriminate between two nonspeech sequences consisting of four pure tones that differed only in the temporal order of the two middle tones (HMLH and HLMH). The frequencies of the tonal components were fixed at 1.4 (H), 1 (M), and 0.7 (L) kHz. The sequences were presented at 76 dB SPL, randomly to either the left or the right ear of the subjects at either of two durations. For each subject ear and for each daily half-session, two-point psychometric functions were constructed and threshold durations were estimated, with the 75% correct performance taken as the threshold. These threshold estimates show that (1) untrained observers need 100–240 msec/tonal component in order to discriminate the temporal order of two short tonal sequences; (2) this threshold value rapidly decreases and reaches an asymptotic duration of 10–20 msec/component around the eighth day of sessionS; (3) contrary to several reports on similar experiments using speech or speechlike stimuli, these threshold estimates indicate that there is no difference in temporal-order discrimination of sequences presented to the left or the right ear. [Supported by NINDS Grant No. 03856.]
Decision process in frequency discrimination
Authors: Jesteadt W. , Sims S.
Published: October 2005

Frequency discrimination performance was measured in 2IFC, same-different, and yes-no paradigms using two methods common in the literature, pure-tone discrimination and FM detection. For the pure-tone method, performance in 2IFC exceeded performance in yes-no by more than the factor of √ predicted by the traditional TSD decision theory analysis. For the FM method, performance in 2IFC exceeded performance in yes-no by less than a factor of √. The subjects were then asked to distinguish between two different modulation ranges. The ratio of performance in 2IFC to performance in yes-no was greater in this FM-discrimination task than in the earlier FM-detection task. These results are consistent with other studies comparing performance in different paradigms for detection of tones in noise and intensity discrimination. [Supported by grants from NIH and NSF.]
Role of place cue in simple-tone pitch perception assessed with temporary threshold shift
Authors: Kim Duck O.
Published: October 2005

Basilar-membrane nonlinearity observed by Rhode [J. Acoust. Soc. Am. 49, 1218 (1971)] is consistent with basalward shifts of the basilar-membrane vibration envelope with increasing amplitude of a simple-tone stimulus. This nonlinear property, which is indirectly confirmed in this study by measurements of temporary threshold shift (TTS) distributions, is exploited to assess the role of the cochlear “place cue” in simple-tone pitch perception by studying pitch-versus-amplitude behavior. Monaural pitch matchings of 12 subjects show two groups of patterns: For simple tones at frequency f0 = 5 kHz, and at amplitudes varying from 25 to 65 dB sensation level (SL), eight subjects show little pitch shift (less than 2% of f0) for various amplitudes, while the other four subjects show large pitch increase (10%–15% of f0) with increasing amplitude. In contrast, monaural measurements of TTS within 5–20 sec after 30-sec exposures to simple tones of f0 = 5 kHz show similar distributions for all tested subjects (three from each group): the TTS distribution is narrow with a single peak at f0 if Le ⩽ 25 dB SL (where Le is the exposure level), and the TTS distribution spreads mainly to higher frequencies and becomes broader (some with double peaks) with increasing Le above 45 dB SL. It is concluded that for simple-tone pitch matching at 5 kHz the place cue plays no significant role with eight of the subjects, whereas it plays a significant role with only the remaining four.
Frequency responses of hearing aids and their relation to word discrimination by hard-of-hearing subjects
Authors: Pascoe David P.
Published: October 2005

Eight adult hard-of-hearing subjects with mild to moderate hearing levels were tested with different randomizations of a monosyllabic word list. They listened through five frequency responses of a master hearing aid. These responses were defined both in terms of 2-cc coupler measurements and of aided versus unaided threshold shifts (functional gains). The differences between coupler and functional gains were consistent among subjects and reflect the effects of ear-canal resonance, head diffraction, and earmold acoustics. Discrimination was consistently better through a response which “normalized” the aided threshold of each listener. The lowest scores were produced through a response which simulated typical hearing aids. The average of differences between these two responses was 18.3%. Further testing replicated these results and also compared the effects of a different word list (P. B.); with this list, the above-mentioned difference was smaller in quiet (6.1%), but much larger in noise (22.1%). [Supported by NIH Grant No. NS 038596 and Mr. G. H. Packwood.]
Design of wearable hearing aids with low noise, low distortion, and wide bandwidth
Authors: Niemoeller A. F. , Starr E. A. , Torick E. L.
Published: October 2005

Wearable hearing aids have been independently developed within the last few years at CBS Laboratories, at Bolt Beranek and Newman, Inc., and at Central Institute for the Deaf. The devices developed by CBS and BBN are master hearing aids in the sense that the electroacoustic characteristics can be changed over wide ranges to accommodate correspondingly wide ranges of hearing impairments in different individuals who will use the devices in different activities and different environments. The device developed at CID was designed for one elderly patient with a moderate receptive hearing loss with the expectation and hope that similar devices can be used effectively for many others with this same type of hearing problem. The design goals for each of the development projects and the methods and devices used in each attempt at achieving the goals are reviewed. Similarities in the efforts with respect to problems in packaging, power requirements, electronics, and transducers are outlined. Areas in which additional development and investigation are needed are suggested.
Computer-aided speech evaluation and speech training for the deaf
Authors: Nickerson R. S. , Stevens K. N.
Published: October 2005

A system built around a minicomputer has been used in a remedial speech-training program on problems of pitch and intonation, timing and rhythm, velar control, voice quality, and articulation. Training is done both by means of tutorial sessions in which a speech teacher coaches a student with the help of several types of visual displays generated by the machine, and through self-instructional sessions in which a student works with the displays by himself. The system is organized in a way that permits display selection, storage and replay of displays produced by teacher and by student, and measurement of display parameters with a simple array of pushbuttons and knobs under the control of teacher or student. Data have been collected to document the students' progress, and the results to date suggest that speech-training procedures utilizing the displays are useful in teaching children to obtain specific measurable objectives relating to each of the problems mentioned above. They also demonstrate, however, the importance of further research on the question of the relative importance of various speech deficiencies for speech intelligibility, and on the design of more effective speech-training procedures that can capitalize on the objective evaluations provided by visual displays. [Research supported by the U. S. Office of Education, Media Services and Captioned Films Branch of the Bureau of Education for the Handicapped.]
Turbulent boundary-layer theory for grazing airflow effects on acoustic resistance of a perforated plate
Authors: Guess A. W.
Published: October 2005

It has been suggested [U. Ingard, J. Acoust. Soc. Am. 44, 1155 (1968)] that the increase in acoustic resistance of a perforated plate due to steady tangential airflow results from the existence of a turbulent boundary layer next to the plate. The fluctuations in the boundary layer are often at a characteristic frequency much less than the acoustic frequency, thus producing effectively constant flow through the orifices, compared with the acoustic oscillations. Hence an increase in acoustic resistance results by enhanced turbulent jet formation. In this paper, theoretical relations are developed according to this concept with use of turbulent boundary-layer theory. Either “smooth-wall” or “rough-wall” turbulent boundary-layer theory can be used, and formulas are developed for the dependence of acoustic resistance on grazing airflow velocity, boundary-layer thickness, and distance along plate. The “rough-wall” theory predicts an exact linear dependence of acoustic resistance on steady airflow velocity, and the order of roughness may be put equal to the diameter of the orifices. The relation of acoustic frequency to the characteristic frequency of turbulent fluctuations is examined. Comparison of the theoretical results with available experimental data shows that either the “smooth-wall” or “rough-wall” theory predicts the observed trends and gives qualitative agreement.
Flow-induced cavity resonances—their modal structure and amplitude characteristics
Authors: Heller H. H. , Bliss D. B.
Published: October 2005

In the 1973 Fall Meeting of the Acoustical Society a color movie was shown by the authors depicting the unsteady pressure and flow phenomena occurring in and near rectangular shallow cavities that are exposed to high-speed flow. In the meantime, a detailed investigation took place on the characteristics of the flow-induced discrete cavity pressure modes and their dependence on pertinent aerodynamic and geometric parameters. It is now possible to estimate the occurrence of resonant modes, their maximum levels, and their amplitude distribution within a cavity over a free-stream Mach number range of 0.2–3.0 for cavities with a length-to-depth ratio from 2 to 5.5. [This research program was supported by the Air Force Flight Dynamics Laboratory of Wright-Patterson Air Force Base, Dayton, Ohio.]
Model for jet noise analysis using pressure gradient correlations on an imaginary cone
Authors: Norum T. D.
Published: October 2005

In previous applications of the method for estimating the noise-generating regions of a jet from correlations of the acoustic pressure gradient near the boundary of the jet, plane surfaces were used for measurement purposes. However, since the boundary of an axisymmetric jet is approximately conical in shape, more relevant data can be obtained through measurements on an imaginary conical surface surrounding the jet. Hence, in preparation for experimentation on a round supersonic jet, the mathematical model necessary to utilize a cone in this method has been developed. The model is proven correct by comparison of the acoustic intensity flux through the cone as determined from this formulation and from exact means when a known source is used as the noise generator. An apparent source distribution on the surface due to the actual source is calculated to determine the feasibility of identifying the actual source in terms of correlations on the surface. The contribution to the farfield intensity is found to be strongly dependent on apparent sources at the projected position of the actual source. This dependence increases with frequency, although the distribution becomes less symmetric than at lower frequencies.
Middle-ear transfer function of the anesthetized Mongolian gerbil
Authors: Schmiedt R. A. , Smith R. L.
Published: October 2005

The middle-ear transfer function of the Mongolian gerbil (Meriones unguiculatus) was obtained using a constant CM criterion with both single electrodes in scala media and differential electrodes in scalae media and tympani. A cancellation technique allowed accurate phase measurement of both CM and ear-canal sound pressure. Results indicate small inter-animal variability and no significant differences between single electrodes and differential electrodes, except for contamination of single electrode recordings by whole-nerve action potentials. With the bulla open, the magnitude of the transfer function has a positive slope of 6 dB/octave up to 200 Hz and is flat from 200 Hz to 1.8, where it begins to fall off at a rate of approximately 12 dB/octave. The CM phase leads to that of the sound pressure by 90° at 100 Hz, is 0° at 600 Hz, and lags by 90° at 1.8 kHz. At high frequencies, the phase lag is greater than 180°. The high-frequency rolloff, steeper than that found in other mammals, is probably due to decreased coupling between the incus and the stapes.
Properties of acoustic middle-ear-muscle reflex in echolocating bats
Authors: Jen P. H-S. , Suga N.
Published: October 2005

Properties of acoustic middle-ear-muscle (MEM) reflex in Myotis lucifugus were electrophysiologically studied. (1) The shortest latency of the reflex in terms of EMG was 3.4 msec for the stapedius muscle (SM) and 4.4 msec for the tensor tympani muscle. (2) Unlike first- and second-order auditory neurons, all tuning curves of single SM fibers were very broad. Motoneurons for the muscle appeared to integrate signals from many superior olivary neurons with different best frequencies to produce such broad tuning curves. (3) The threshold of the reflex in terms of EMG decreased with an increase in stimulus duration. With a long tone burst, the lowest threshold obtained was 20 dB SPL in both muscles. (4) The MEMs contracted maximally at the beginning of the reflex and then tonically contracted to some extent during the stimulus. The feedback gain of the reflex in terms of cochlear microphonic was 1.0 at the peak of the MEM contraction and 0.3–0.5 during a quasisteady contraction. (5) A frequency-attenuation curve of the reflex showed that attenuation was maximal at about 30 kHz and reduced with a slope of 17 dB/octave at above it. [Supported by NSF grant GB-40018.]
Interaural attenuation as measured with differential electrodes in guinea pig and chinchilla
Authors: Teas D. C. , Nielsen D. W.
Published: October 2005

Acoustic energy delivered to one ear can, through cross conduction, stimulate the contralateral cochlea. The effects of cross conduction can complicate studies attempting to define binaural mechanisms. For instance, acoustic energy delivered directly to one ear can interact with the cross-conducted acoustic energy delivered to the other ear, thus confounding the independence of the two auditory channels. This constraint upon the independence of the acoustic channels might be more severe for small animals such as the guinea pig and chinchilla that for larger animals such as the cat, monkey, and man. We have determined isopotential curves (Turn I, differential electrodes) for the guinea pig and chinchilla from which interaural attenuation has been estimated. Below 10 kHz, interaural attenuation decreases from about 50–60 dB below 1 kHz to about 40–50 dB around 10 kHz. Differences in curves due to open and closed bullae appear for some animals. For ipsilateral stimulus levels greater than 90 dB SPL, frequencies above 10 kHz produced direct electrical pickup in differential electrodes whether they were into the cochlea or suspended in a saline-filled bulla. Contralateral stimulus levels above 100 dB produced similar phenomena.
Low-frequency sound propagation in the marginal ice zone of the Greenland Sea
Authors: Numrich S. K.
Published: October 2005

Acoustic propagation measurements were made in the marginal ice zone of the Greenland Sea using a 290-Hz CW source. The source was towed by a ship transiting inside the ice field while the receiving hydrophones were suspended from a ship drifting in open water near the ice boundary. Both the source and the receivers were located within the surface sound channel. Descriptions of the sea ice canopy were provided by aerial radar and photography during the period of operation. Transmission losses were measured for ranges up to 65 nautical miles and the characteristics of amplitude envelopes of signal and noise samples were examined. Comparisons of the transmission loss measurements with ray acoustic and normal-mode models indicate that low-frequency signals couple well to the surface sound channel typical of the arctic environment and that losses due to scattering from the under ice surface are minimal. The measured losses are markedly lower than the values predicted by either of the models used in the comparison.
Amplitude fluctuation of underwater sound transmitted in the surface duct
Authors: Urick R. J.
Published: October 2005

A short field experiment has been performed to study the amplitude fluctuation of sound transmitted through the surface duct and received by hydrophones within and below the duct. Short pulses near 15 kHz and CW sound at 1120 Hz were transmitted to sonobuoy hydrophones at depths of 60 and 300 ft in a 180-ft duct at ranges of 2, 4, 6, 8, and 10 miles. Analysis showed that below the duct at beth frequencies, the amplitude distribution was Rayleigh, in keeping with the view that below-duct sound is surface-scattered sound. Within the duct, the amplitudes were Rayleigh-distributed at the higher frequency, but were less variable at the lower frequency, with a coefficient of variation between 8% and 26%, independent of range. This finding is consistent with the idea that the sea surface was effectively rough at the higher frequency, with a Rayleigh coefficient R = kH sinθ equal to about 2 at the angles of 2° to 3° required for duct propagation, but was effectively smooth at the lower frequency where R was of the order of 0.1. In short, it appears that, as one would expect, the roughness of the sea surface determines the fluctuation of duct-transmitted sound.
Near-bottom 4-kHz reflectivity observations in real time
Authors: Tyce R.
Published: October 2005

A sea-going digital computer system has been utilized to process and display quantitative near-bottom 4-kHz sounding data in real time for an abyssal hill region of the sea floor 200 miles west of San Diego. Over a region approximately 50 miles square, variations in bottom reflectivity of as much as 10 dB were observed, with abrupt changes in sediment character and reflectivity (as much as 7 dB). Four precisely navigated cores were taken from the area for physical property analysis, one of which sampled a buried 3-cm-thick manganese layer. Quantitative 4-kHz reflectivity data from the above area as well as several others in the Pacific are being further analyzed in an attempt to infer acoustic attenuation values for sedimentary layers from variations in layer reflectivity with burial depth. Preliminary results are in good agreement with published values of directly measured attenuation in ocean sediments. A value of 0.12 dB/m at 4 kHz obtained for calcareous ooze of approximately 75% porosity from the Carnegie Ridge represents a relatively low value in comparison with published attenuation values, suggesting significant lithification of this high-porosity sediment.
Mean of the field for cylindrically spreading waves in a random medium
Authors: Fitelson Michael M.
Published: October 2005

The mean value of the field for a cylindrically spreading wave in a random medium is obtained as the exact solution of an equation derived from the wave equation when forward scattering is dominant. The region of validity for this equation is obtained. It is shown that the region of validity extends far beyond the region where random effects just begin to become significant.
Evaluation of the role of vowel duration as a perceptual cue in the fortis-lenis distinction in word-final position
Authors: Hogan J. T. , Rozsypal A. J.
Published: October 2005

Heretofore measurements from sonograms have indicated that the durations of vowels before fortis and lenis consonants exhibit a systematic difference, the latter being longer approximately in a 3 : 2 ratio to the former. Experiments with synthetic speech have shown that vowel duration is at least a sufficient cue for the perception of the fortis-lenis in final position. The role of this cue is evaluated for natural speech signals by the use of digital gating on a PDP-12 digital computer. The stimuli were comprised of English words ending with stops, fricatives, and clusters after tense and lax vowels. Four different durations were gated from the vowel nucleus. The stimuli were gated in four equal intervals at zero crossings to prevent unwanted transients and the stimuli were presented in random order. The method employed was the forced-choice the 50% cross-over points under the different consonant and vowel conditions. In some cases, recognition curves could not be established even after 75% of the vowel was gated. The results of the experiment indicated that vowel duration, voicing, and the duration of silence between the vowel and the final release transient vary in weight as cues under different vowel- and consonant-type conditions.
Effect of selective adaptation on the identification of speech sounds
Authors: Diehl Randy L.
Published: October 2005

An experiment was performed to determine the effect of selective adaptation on the identification of synthetic speech sounds which varied along the phonetic dimension place of articulation. Adaptation with a stimulus of a particular place value led to a reduction in the number of test stimuli identified as having that place value. An identification shift was obtained even when the acoustic information specifying place value for the adapting stimulus (burst-cued) had little in common with the information specifying place value for any of the test stimuli (transition-cued). Removing the vowel portion of an adapting stimulus eliminated identification shift only when the resulting stimulus was no longer perceived as speechlike. The results indicate that at least part of the adaptation effect occurs at a site of phonetic, nor merely acoustic, feature analysis.
Comparison of two diagnostic intelligibility test methods
Authors: Smith Caldwell P.
Published: October 2005

Speech processors including analysis/synthesis systems and waveform digitizers were tested with both the six-speaker Diagnostic Rhyme Test (DRT) of Voiers et al., and the Consonant Rhyme Test (CRT) of Preusse. Analysis of response data from two eight-subject listener teams confirmed than mean intelligibility scores obtaines with the DRT and with the CRT were highly correlated (γ = 0.969, with 9 df). Mean scores were related by the linear regression model: S(drt) = 47.07 + 0.582 S(crt), with standard error of regression = 1.87. A diffuse pattern of correlations between the two sets of feature scores was revealed, the extreme cases being for DRT feature sibilation-present, significantly correlated with only one CRT feature score, unvoiced fricatives, while DRT feature graveness-present was significantly correlated with all CRT features: unvoiced stops (γ = 0.675), unvoiced fricatives (γ = 0.699), liquids/semivowels (γ = 0.725), nasals (γ = 0.757**), voiced fricatives (γ = 0.860**), and voiced stops (γ = 0.937***). Findings indicate that, with the appropriate model, mean intelligibility scores obtained with the DRT and with the CRT are equivalent; however, the two tests differ significantly in assessing specific deficiencies of systems.
Discrimination of speech sounds by the chinchilla: /t/ vs /d/ in CV syllables
Authors: Kuhl Patricia K. , Miller James D.
Published: October 2005

Two female and two male talkers recorded two tokens of /ti, ta, tu, di, da, du/. Voice-onset times ranged from + 40 to + 128 msec for /t/'s and from − 200 to + 24 msec for /d/'s. Four chinchillas were trained to respond differentially to single tokens of one talker's /tu/ and /du/. When an animal mastered the discrimination, the task was complicated by adding more items from the catalog of /t/'s and /d/'s. Intensity was varied randomly over a 10-dB range throughout the experiment. In the final sessions, an animal must correctly respond to all 48 CVs. All four animals are currently maintaining 90% correct, or better, in this condition. Chinchillas can learn to discriminate /t/ from /d/ in CVs in spite of variations due to tokens, talkers, vowels, and intensity. [Supported by NIH Grants NS 03856 to CID and RR00396 to the Biomedical Computer Laboratory of Washington University.]
Speaker sex identification from voiced, whispered, and filtered isolated vowels
Authors: Lass Norman J. , Waters Lucille T. , Tyson Victoria L.
Published: October 2005

The purpose of this investigation was to determine the relative importance of the speaker's laryngeal fundamental and vocal-tract resonance characteristics in speaker sex identification tasks. Six sustained isolated vowels (/i, ε æ, a, o, u/) were recorded by 20 speakers, 10 males and 10 females, in a normal (voiced) and whispered manner. A total of three master tapes were constructed from these recordings, representing the three experimental conditions in the study: voiced, whispered, and filtered. The filtered tape was constructed from the voiced recordings by playing the voiced tape through a variable filter with a 255-Hz low-pass cutoff setting. Each tape contained excised 500-msec segments of all speakers' six vowel productions in a randomized order. The tapes were played to 15 listeners under headphones for speaker sex identification judgments and confidence ratings of their evaluations based on a seven-point scale, in which a rating of 1 represented a guess and 7 indicated complete confidence in their decisions. Results of their judgments indicate that, of the 1800 identifications made for each tape (20 speakers × 6 vowels × 15 listeners), 95% were correct for the voiced tape, 93% were correct for the filtered tape, and 75% were correct for the whispered tape. Moreover, the listeners were more confident in their Judgments on the voiced and filtered tape (mean confidence ratings of 5.6 and 5.4, respectively) than they were on the whispered tape (mean confidence rating of 3.0). These findings indicate, contrary to some previous research, that the laryngeal fundamental appears to be a more important acoustic cue in speaker sex-identification tasks than the resonance characteristics of the speaker. Implications of these findings and comparisons with previous research are discussed.
Memory and the dichotic right-ear advantage for stop consonant-vowel syllables
Authors: Porter Robert J. , Guillory Michael J.
Published: October 2005

In some dichotic listening tasks, subjects are required to identify single dichotic pairs immediately after each pair is presented. In other tasks, subjects may be asked to delay recall until after a list of pairs has been presented. The greater accuracy of the identification of right-ear signals, obtained in both types of studies, has sometimes been treated as reflecting the same aspects of cerebral laterization even though two tasks may implicate laterilized mechanisms in different ways. In order to explore this possibility, subjects were asked to identify dichotic members of pairs of stop consonant-vowel syllables presented under two conditions: (a) immediate identification after each pair, or (b) recall after rapid presentation of three dichotic pairs. Preliminary data-analysis has revealed the involvement of a memory component in the three-pair task (i.e., serial position effects and lower identification scores). This memory factor can influence ear-advantage measures since it tends to be different depending on the ear recalled. The results suggest that dichotic-list recall tasks may tap different or additional aspects of cerebral laterilization than do single-pair tasks.
Perception of temporal order in vowel sequences with and without formant transitions
Authors: Dorman M. F. , Cutting J. E. , Raphael L. J.
Published: October 2005

The temporal order of phoneme sequences in running speech can be identified at much faster rates than in repeating vowel sequences. The superiority of running speech may be largely due to the presence of formant transitions. In a series of five experiments we found that (a) certain sequences of four vowels are more difficult to identify than others, (b) the difficulty in identifying these sequences is related to the phenomenon of auditory stream segregation, (c) streaming cannot be effectively suppressed by replacing most of the vowel with silence, but it can be inhibited by replacing most of the vowel with formant transitions, (d) the vowel component primarily responsible for streaming is the first formant, but the second formant may be more important for certain sequences, and (e) the identification of brief formant-connected sequences is further constrained by the adequacy of the acoustic cues for the perception of vowels as opposed to other segments.
Automatic separation of simultaneous speech of two talkers
Authors: Parsons T. W.
Published: October 2005

A common type of interference in speech transmission is that caused by the speech of a competing talker. While the brain is good at discerning individual voices in such a situation (the “cocktail party effect”, it relies heavily on the availability of binaural data. When voices compete over a single channel, separation is much more difficult and intelligbility is degraded. The present paper describes methods of attenuating this interference by selecting the components of the desired signal in the Fourier transform of the input. Implementation of these methods is described, and problem areas and limitations are discussed. Preliminary results are presented, with examples of separation achieved under certain simplifying constraints.
Temporal masking of clicks by noise under diotic and dichotic listening conditions
Authors: Yost William A. , Berg K. M.
Published: October 2005

Forward, backward, and combined forward-backward masking of a 1-msec click by noise bursts were examined for N0S0 and N0Sπ stimulus configurations. The silent interval between the noise masker and the click ranged from 0 to 30 msec for forward and backward masking conditions. For combined forward-backward masking, the silent interval between the two noise maskers ranged from 1 to 60 msec, and the click was positioned at various points within this interval. The results, which were consistent with previous reports, indicated that masking level difference (MLDs) are obtained for both forward and backward masking. The largest MLDs were obtained in the combined forward-backward masking conditions. In both the N0S0 and N0Sπ stimulus configuration, the amount of masking in the combined forward-backward masking conditions varied as much as 10 dB as the click was moved within the intermasker interval. The results of this study are compared with data from investigations of masking with forward and backward fringes. In addition, the results are discussed in terms of the additivity of forward and backward masking. [These experiments were conducted with support from National Institute of Health (NIH) Program Project Grant, an NIH training Grant, and an NIH Research Grant.]
Interaural time versus interaural intensity in a lateralization paradigm
Authors: Yost William A. , Tanis David C. , Nielsen Donald W. , Bergert Byron
Published: October 2005

In a two-interval lateralization procedure, observers were to judge if a stimulus presented with an interaural intensive difference was right or left in lateral space of the same stimulus presented with only an interaural temporal difference. The stimuli were pure tones of 500 and 1000 Hz, and a 1000-Hz low-pass noise. All stimuli were presented at both 65 and 55 dB SPL. For each value of interaural time (ranging from 0 to 1000 μsec across all stimuli), a function was determined which related proportion of “right” judgments to the value of the interaural intensive difference. Changes in interaural time moved the lateral image a decreasing amount of lateral distance as the interaural temporal difference increased from zero. Changes in interaural intensity, however, mapped linearly onto lateral position. Thus, the procedure provided a means for comparing the lateral location of images produced by interaural differences of time and intensity. [These experiments were conducted with support from National Institute of Health (NIH) Program Project Grant, an NIH training Grant, and an NIH Research Grant.]
Sensitivity to interaural differences in the envelopes of amplitude-modulated waveforms
Authors: Neutzel J. M. , Hafter E. R.
Published: October 2005

Henning has recently demonstrated [J. Acoust. Soc. Am. 55, 84–90 (1974)] that interaural delays in either the total waveform or the envelope phase of high-frequency amplitude-modulated sinusoids can be detected despite the presence of low-frequency masking. We have extended this design using wider noise bands chosen to mask the harmonics of the modulation frequency. Stimuli consisted of various high-frequency sinusoidal carriers, 100% modulated by a 300-Hz tone. In addition, we studied the effects of carrier amplitude and duration on interaural detection so as to make direct comparisons to lateralization of pure tones. In general, we found sensitivity to phase differences in the modulation frequency to be slightly less than that reported for low-frequency masker had little effect. In a second design, we examined the detectability of interaural phase while presenting an amplitude-modulated signal to one ear and a pure tone at the modulation frequency to the other. Here we found essentially no binaural interaction. The results of both experiments indicate that the phase information used successfully in the first design is carried only in the high-frequency bands surrounding the carrier frequency. [Supported in part by grants from the National Institutes of Health.]
Computational method for the transmission of sound in nonuniform ducts with flow
Authors: Eversman Walter
Published: October 2005

A method of weighted residuals has been developed to investigate the transmission of sound in nonuniform ducts carrying a steady mean flow. By using an assumed solution in terms of a set of appropriately chosen basis functions, the set of three partial differential equations governing sound propagation is reduced to a set of coupled first-order ordinary differential equations for the axial variation of the undetermined coefficients in the assumed solution. These equations can be integrated to provide a transition matrix relating the acoustic state at the two ends of the nonuniformity. The transition matrix is used to generate reflection and transmission coefficients for the nonuniformity and can be used to generate the acoustic field in the nonuniform section. To verify the method, we have used it to compute the transmission characteristics of a straight uniform duct with flow (no reflections or spurious model generation) and a duct with no flow (we used M = 0.01 at low frequency, since this is a singular point in the governing equations). Comparison with known results was excellent. Extensive computations have been made for specific duct geometries and flow fields and the method appears to be both practical and reliable. [NASA Grant NGR 17-003-018.]
Curvature effect on propagating waves in point-excited spherical and cylindrical shells submerged and in vacuo
Authors: Schwartz Jeremy
Published: October 2005

The effect of shell curvature is retained in the derivation of geometrical acoustics solutions from the exact propagating wave formulation for spherical and circular cylindrical shells, submerged and in vacuo. It is found that for submerged shells the curvature effect is of the order of the inverse of the wave radius ka, while for shells in vacuo it is of the order of the square of the inverse of the wave radius. In the further approximation of small wave thickness kh, the solutions obtained here for shells in vacuo satisfy the eikonal equation determined by O. A. Germogenova for shells in vacuo [O. A. Germogenova, “Geometrical Theory for Flexure Waves in Shells,” J. Acoust. Soc. Am. 53, 535–540 (1973)]. In addition, in this further approximation, although the energy transport vector is not normal to the phase front, it is tangential to a geodetic path on the shell surface. [Supported by Office of Naval Research, Code 412.]
Effect of nonsymmetric flow resistance upon orifice impedance
Authors: Posey J. W. , Compton K. J.
Published: October 2005

Previous laboratory work has indicated that dc flow resistance of an orifice may be dependent upon the direction of flow, especially in the presence of a crossflow on one side of the hole. Here, an analytical study is presented which assumes a nonreactive orifice in an infinite baffle. An ambient pressure difference, Δp, exists across the orifice, and the pressure on one side varies sinusoidally with amplitude 1.0. The resultant flow is taken to be quasisteady. The orifice resistance, Δp/u, is discontinuous at zero velocity and exhibits the constant values R+ and R− for u > 0 and u < 0, respectively. An expression is found for the pressure difference, d = (Δp)ū=0, required for zero net flow as a function of the resistance ratio R+/R−. It is found that if 0.5 ⩽ R+/R− ⩽ 2.0, then |d| ⩽ 0.22 and a frequency analysis of the flow velocity (for δp = d) shows little energy in harmonics of the excitation frequency. Thus, for R+/R− near unit, an equivalent constant resistance, Re, which accounts for small energy loss to harmonics, may be an adequate expression for the acoustical impedance of the orifice for some purposes.
Standing waves in the presence of a temperature gradient
Authors: Ross David F. , Crocker Malcolm J.
Published: October 2005

In many practical problems such as those involving the measurement of the impedance of materials and of the transmission loss of mufflers, it is necessary to measure standing waves. Temperature gradients in the fluid can complicate the analysis problem. The standing-wave equation is derived for the case of standing waves in the presence of a linear temperature gradient. A closed-form solution is developed and the shape of the standing waves are shown for arbitrary test eases. A numerical technique is also developed as an alternate solution consisting of a discrete element approximation. The results of each type of solution are compared using the test cases.
Magnetoacoustic effect for germanium
Authors: Gan W. S.
Published: October 2005

We use a warped energy surface model and relaxation time expressed as a Fourier summation. Semiclassical treatment is used. We describe Q, the heat dissipated per unit volume, and time in terms of integrals involving the Boltzmann distribution function and evaluate these integrals using an ordinary algebraic method. Q is then expressed in terms of these parameters: transition rate of electrons between valleys of the energy surface model, gauge, electric field induced by the sound wave, magnetoconductivity, etc. We next find these parameters in terms of quantities known numerically and make use of values of magnetoconductivity obtained in a previous paper [W. S. Gan, Phys. Lett. A (to be published) (1974)]. Numerical values for the ultrasonic attenuation coefficient for indiumdoped p-type germanium In-1 to In-5 are obtained. Our results agree with the Suzuki et al. [Phys. Lett. A 23, 44 (1966)] and Pomerantz [Proc. IEEE 53, 1438 (1965)] data on the shape of attenuation curves and the temperatures for maximum attenuation.
Electronically controlled wire drawing under macrosonic influence
Authors: Langenecker B.
Published: October 2005

Macrosound (i.e., high-amplitude ultrasound) can be effectively applied in metal deformation processes due to its peculiarity of causing a significant reduction of forming forces [F. Blaha and B. Langenecker, Naturwissenschaften 20, 556, 557 (1955)]. Thus materials can be drawn with larger area reduction or at higher deformation rates, respectively; materials which resist conventional treatments can be also formed under the influence of macrosound [Proc. First Int. Symp. on High-Power Ultrasonics, IPC London (1972)]. Our macrosonic wire-drawing machines operate at a nominal frequency of about 20 kHz and intensities up to 1000 W, depending on material, diameter, and drawing speed (up to 10 m/sec). This paper describes technical details and presents performance data. In particular, the electronic measuring and control instruments for easy operation and automatic control of both drawing rate and insonation will be explained and demonstrated in our booth.