bluuebunny/crossref_metadata_2025 huggingface dataset:
Noise dosimeters: on measurement reliability and instrument accuracy
Authors: Earshen John J.
Published: October 2005

Sporadic reports of substantial variations in measurements of exposure noise dose in the workplace performed with contemporary dosimeters have generated concern in the community of users. Measurement differences ranging up to many hundreds of percent have been reported. Differences have been observed when several dosimeters of different makes have been used simultaneously as well as in instances where apparently identical dosimeters have been used. Moreover significant differences have been observed in day to day tests on a given worker. These tests have been made with the same dosimeters in an apparently invariant working environment. Careful investigations of the properties of the ambient noise fields and limitations of microphones worn on the body explain, and sometime mitigate, some of the measurement variations. Remaining differences have been attributed by some users to inadequate “accuracy” of the dosimeters. ANSI S 1.25 stipulates that type 2 SLM performance is required for dosimeters. Some individuals have proposed changing to type 1 dosimeters (of even type 0 SLM's). The problems are quite complex and cannot be resolved by simple upgrading or resorting to SLM's. This paper identifies several sources of measurement variability which are introduced by generic configurations of dosimeters. These include: detector performance in the presence of impulsive noise when a 5-dB exchange ratio is used, and uncertainty in achieving threshold cutoff. It is concluded that present standards and applications practices must be changed to achieve improved measurement reliabilities.
Design of housing for aircraft noise
Authors: Long Marshall
Published: October 2005

A methodology has been developed for predicting interior noise levels from exterior sources with considerable precision. The design features used in a housing tract located at an Ldn 80.5 level near the end of the runway at Los Angeles International Airport are shown. Interior noise levels were reduced to an Ldn 45 or below in all bedrooms. Seventeen 24-h measurements were taken after the project was completed. The average prediction error was 0.08 dB and the standard deviation was 0.94 dB.
Active attenuation of acoustic disturbances in high energy pulsed lasers
Authors: Lavan M. J. , French F. W>
Published: October 2005

The potential advantages of the active attenuation of acoustic disturbances in high energy pulsed lasers have been analyzed, using the theory developed for the control of sound in long ducts [M. A. Swinbanks, J. Sound Vib. 27, 411–436 (1973)]. The results show that active attenuators, which are especially effective at the lower audio frequencies, could be used in conjunction with passive mufflers to significantly reduce the total muffler volume required to damp the acoustic disturbances to an acceptable level. Only modest acoustical power would be required because the active attenuation system would be used to damp just the fraction of the acoustical disturbance which is reflected back toward the optical cavity by the thermal interface created by the previous laser pulse. The additional attenuation provided by an active system could also result in higher laser pulse rates, and thus higher average power. The design requirements for an experimental demonstration of the potential benefits of active attenuation for pulsed laser operation will also be discussed.
The use of partial and multiple coherence spectral analysis of accelerometer recordings in source and path identification of structure-borne noise on surface ships
Authors: Kalme J. S. , Winegrad D. L.
Published: October 2005

Partial and multiple coherence spectral analysis was performed on accelerometer data, recorded on a U.S. Navy surface ship. A total of 48 accelerometers were mounted at predetermined locations on the ship, and vibration data were recorded on a 14-channel instrumentation tape recorder. The data were recorded in four groups, each consisting of twelve pickups. Taking groups of four pickups at a time with high pairwise coherences, a four-channel analog-to-digital converter and minicomputer were used to digitize and process the data. Partial and multiple coherence spectral analysis was performed on the digitized data. The analysis was found to be very useful in identifying major sources of structure-borne noise at various frequencies. Also the analysis was helpful in identifying major noise paths. The analysis was performed at the David W. Taylor Naval Ship Research and Development Center at Annapolis, MD, under the Surface Ship Silencing Program.
Sound transmission through triple glazed windows
Authors: Quirt J. D.
Published: October 2005

Measurements have been made to compare the sound transmission loss of double and triple glazed windows. The results of a series of laboratory measurements conforming to ASTM standard E90 are presented. By reference to these data some of the differences in sound transmission through double and triple glazing are evaluated.
Upward spread of masking in normal and impaired ears
Authors: Picard Michel , Couture Francine
Published: October 2005

Upward spread of masking—defined in terms of indirect masking above the frequency band of a masker—was studied in normals and subjects with high frequency hearing loss. Pure-tone auditory thresholds were obtained at discrete frequencies in quiet and in three levels of masking noise. The masker consisted of a one-third octave band of noise centered at 1000 Hz. It was presented at 70, 80, and 90 dB SPL. Comparisons were made of threshold shifts as well as changes in masking, irrespective of unmasked thresholds. Results show the presence of upward spread of masking in the two groups. They also indicate stability of the upward spread of masking in the experimental group at levels of 80 and 90 dB.
Propagation of sonic booms in the upper atmosphere
Authors: Rogers Peter H.
Published: October 2005

The physics of sonic boom propagation in the upper atmosphere is reviewed. Particular attention is given to the strengthening of the ascending wave due to decreasing density and to the formation of caustics near the turning point. Upward going sonic booms may be returned to the ground due to winds in the stratosphere or high temperatures in the thermosphere. The two cases are compared and contrasted. The possibility of measuring such booms at high altitudes using microphones, parachute deployed from small rockets, is discussed.
Application of the Biot sediment model to the prediction of shallow-water transmission loss
Authors: Beebe J. H. , McDaniel S. T. , Rubano L. A.
Published: October 2005

Shallow-water transmission loss is highly dependent on the nature of the seabed. Our ability to predict losses is thus limited by our ability to predict the acoustic characteristics of the bottom. Propagation-loss data from three shallow-water sites having different bottom types is presented. The bottom characteristics at each site were derived from the Biot sediment model using grain-size and porosity data obtained from the analysis of core and grab samples. Using the derived bottom parameters as an input, the predictions of normal-mode theory are compared with the measured propagation loss.
The little bang theory—Energy from inertial fusion
Authors: Bangerter Roger O.
Published: October 2005

Calculations show that it may be possible to ignite small thermonuclear explosions with an ion accelerator or laser. The process involves the implosion of small targets to achieve extreme temperatures and densities. The implosion can be described as a sequence of shock waves followed by adiabatic compression. The strength and timing of the shock waves are important in achieving proper conditions for thermonuclear burn. Other important issues include the uniformity of the converging shock waves and the influence of these shock waves on fluid instabilities. These issues are not fully understood and constitute an important area of research in inertial fusion. In order to produce commercial energy, it will be necessary to develop combustion chambers, target fabrication factories, and efficient drivers (accelerators or lasers). These will be briefly discussed. In particular, acoustical phenomena will play an important role in combustion chamber design. [Research performed under the auspices of the U.S. Energy Research and Development Administration under Contract No. W-7405-Eng-48.]
Performance bounds in speech motor control of jaw movements
Authors: Nelson Winston L.
Published: October 2005

A simple dynamic model for jaw movement is developed, using x-ray pellet data of jaw movements during speech to estimate the important parameters. Using this model, the techniques of optimal control theory have been applied to determine the performance bounds on jaw articulation effort and time as a function of articulation displacement. Since these bounds apply regardless of the actual motor control strategy employed, they can be used to investigate timing effects in speech production.
Serial ordering units for speech production: segments or other syllabic subunits
Authors: Shattuck-Hufnagel S.
Published: October 2005

Serial ordering errors in spontaneous speech often involve individual phoneme-like segments, but seldom larger syllabic components containing both consonants and vowels. This observation suggests that syllabic structure provides a framework for the serial ordering of individual phonemic segments, while larger subsyllabic units and entire syllables do not themselves undergo such ordering during normal production planning (Shattuck-Hufnagel 1979; Shattuck-Hufnagel and Klatt 1979). When speakers repeated syllable sequences constructed by alternating pairs of consonants in conflicting patterns (e.g., PAN FILL FUN POLL, where initial /p, f/ alternate in the pattern ABBA, final /n, l/ in ABAB), 95% of the errors involved a change in a single segment and only 5% involved a CV, VC, or CVC unit. These findings support the view that speech production planning involves the serial ordering of phoneme-like segments, and not of larger syllabic components. Further questions about the nature of position constraints on segments interacting in errors, and about the role of word stress in constraining single-segment errors, are also being explored using this method.
Vector intensity field of noise sources with a new microphone array
Authors: Williams Earl G. , Maynard J. D.
Published: October 2005

A new microphone array system is being constructed to study the radiation from noise sources and nonsteady state sources using the principles of nonwavelength limited acoustical holography. The system can provide an “acoustic snapshot” of the pressure in a plane containing an array of up to 1024 microphones with a total data acquisition time of less than 160 μs. Up to 1024 snapshots can be recorded in a time series to provide an “acoustic filmstrip.” Using digital holographic techniques, a corresponding filmstrip of the vector intensity (the energy flux) of the sound field can be reconstructed in the region above the source. This intensity filmstrip can be used to visualize the time evolution of the energy flow from the sources to the farfield. This new system will be described and some preliminary results will be shown.
Hydrophone nonlinearity measurements
Authors: Moffett Mark B. , Blue Joseph E.
Published: October 2005

For various practical reasons, it is often desirable to make parametric source performance measurements at relatively short ranges (≲50 m). This introduces two potential problems: (1) farfield conditions are not attained, and (2) hydrophone nonlinearity can result in spurious difference-frequency voltages. The first problem has been largely solved by the development of nearfield models for parametric sources. The second problem has long been recognized, and is usually solved by selection of a hydrophone having sufficiently low second-order sensitivity at the primary frequencies. Measurements of this parameter are reported for a number of different hydrophones over the frequency range 15–140 kHz. Hydrophones of the same type and first-order sensitivity can have quite different second-order sensitivities. The nonlinear response is square law for many, but not all, of the hydrophones tested. [Work support by Naval Material Command.]
Phase calibration of hydrophones
Authors: Luker L. D. , Van Buren A. L.
Published: October 2005

Determination of the phase information in a received signal requires knowledge of the phase angle of the receiving sensitivity of the measuring hydrophone. Except for frequencies well below the lowest hydrophone resonance, this phase angle varies considerably with frequency. This paper describes the extension of conventional reciprocity calibration to include phase. It also describes a unique measurement procedure that eliminates phase errors resulting from uncertainties in element location and sound speed. Several hydrophones are calibrated using the new procedure. Measured results are in good agreement with theoretical results based on diffraction constant calculations.
Impedance-transfer technique for quality control monitoring in rubber production
Authors: Corsaro R. D. , Nelson A.
Published: October 2005

A new acoustic technique is described for monitoring the batch-to-batch consistency of rubber properties. Previously, a velocimeter was described which was suitable for acoustic property determinations at 5 MHz on 3 mm thick, 1 cm diameter, ASTM rubber samples [Corsaro, Jarzynski, Burns, and Moniz, paper A8, J. Acoust. Soc. Am. Suppl. 1 66, S2 (1979)]. The present device extends this type of measurement to lower frequencies (70 Hz to 20 kHz) and larger sample sizes (typically 2 cm thick and 15 cm in diameter). This impedance-transfer technique involves sandwiching the rubber sample between a shaker table and an upper covering plate, each section containing an accelerometer. The output signal of the upper accelerometer is referenced to that of the lower, and is used to determine the amplitude loss and phase shift of the vibration due to the presence of the rubber sample. These are shown to correlate well with acoustic properties of the material, including previous velocimeter measurements. Further, the measurement requires less than 5 min by operators without technical expertise, and may use uncut portions of a larger rubber sheet.
Short-term adaptation in normal and acoustically-traumatized ears
Authors: Gorga Michael P. , Abbas Paul J.
Published: October 2005

A forward masking paradigm was used to measure short-term adaptation in normal and acoustically traumatized ears. N1 amplitude was measured to a tone-burst probe of fixed frequency and level while masker intensity (Lm) and duration (Tm), as well as interstimulus interval (Δt) were varied. Initially, masker and probe frequency were 4000 Hz and Tm and Lm were varied. Probe-elicited N1 amplitude was measured at a fixed Δt. These probe response versus Tm functions were modeled exponentially, yielding time constants that did not differ between normal and exposed ears. Recovery from short-term adaptation was examined by holding Tm constant and measuring probe response as a function of Δt. When the decrement (amount by which probe-elicited N1 amplitude was reduced by the masker) versus level functions were fit with an exponential model that accounted for long-term effects, no differences were observed between recovery time constants from normal and traumatized ears. Finally, response growth to the masker was estimated by examining the decrement in probe response as a function of Lm. Acoustically traumatized ears revealed steeper growth functions, suggesting steeper single-fiber rate versus level functions.
Suppression effects for complex stimuli
Authors: Stelmachowicz Patricia G. , Small Arnold M. , Abbas Paul J.
Published: October 2005

A pulsation threshold paradigm was used to evaluate how suppression effects occur within complex stimuli. Stimuli were chosen to represent a continuum of spectral complexity ranging from sinusoids to complexes with one and two suppressors. Results indicate that mutual suppression effects exist between the response to components of complex stimuli. For frequencies above a single suppressor, the suppression region is broad whereas below a suppressor, the region is relatively narrow. With two suppressors, little additivity of suppression is seen. When they are spaced closely, the response to the higher-frequency suppressor is reduced, presumably due to the low-frequency suppressor; this tends to diminish spectral contrasts despite considerable suppression at frequencies between the two suppressors. Enhancement of contrasts is greatest when suppressors are widely spaced and when both are presented at moderate levels (⩽60 dB SPL). These data suggest that suppression may not play a simple role of “peak enhancement” in the peripheral coding of steady-state vowels.
Spatial receptive fields of neurons in the primary auditory cortex (AI) of the cat
Authors: Middlebrooks John C. , Pettigrew John D.
Published: October 2005

We have explored the representation of sound location by neurons in AI. Spatial receptive fields were determined by systematically varying the location of a tonal stimulus within a free sound field while recording from single neurons. The directionality of the external ear was estimated by recording intensity levels inside the acoustic meatus with a probe microphone. Approximately half of the units encountered were selective for sound location. Hemifield units had receptive fields extending from a sharp medial border to beyond the contralateral pole of the sound field. The receptive fields of axial units were completely circumscribed (20°-60° in diameter) and all fell along the acoustical “axis” of greatest sensitivity of the contralateral pinna. Most hemifield units had characteristic frequencies (CF's) less than 12 kHz, while the CF's of axial units were greater than 12 kHz. Location selective neurons were topographically segregated from location insensitive, omnidirectional, neurons. These results are consistent with the presence in AI of stages of at least two apparently independent lines of auditory processing. [Supported by West Coast Neuroscience Consortium (to JCM), NIH-USPHS grants EY 1909 and EY 1391 (to JDP), and NS 10414 (to Dr. M. M. Merzenich).]
Differential effect of at rest eye closure and orbicularis oculi contraction (squinting) on acoustic reflex
Authors: Robinette Martin S.
Published: October 2005

Previous eye closure studies have suggested muscle tension is responsible for acoustic reflex (AR) enhancement during light eye closure (A. L. Corcoran, M.Sc. dissertation, University of South-hampton, England, 1976). AR threshold and magnitude were determined for nine normal hearing adults under counterbalanced conditions: (1) eyes open, (2) lightly closed, and (3) tightly closed (contraction of orbicularis oculi). For a 1-kHz stimulus a 1.1 dB difference was noted between thresholds for eyes open or lightly closed. Squinting however, resulted in a significant 3.6- and 4.7-dB enhancement over the eyes open and closed conditions, respectively. Broadband noise stimuli resulted in a marked enhancement of 9.8 dB while squinting. All conditions differed significantly for the noise stimuli. AR magnitude, however, did not differ across eye closure conditions for either stimuli. Results are compared with previous data on the effects of visual, tactile, olfactory, and mental tasks [Robinette et al., J. Acoust. Soc. Am. Suppl. 1 64, S107 (1978).]
Electrode placement for binaural auditory brainstem responses
Authors: Moulton B. J. , Milliken F. T. , Brey R. H. , Jones K. O.
Published: October 2005

A midline electrode placement configuration is indicated to avoid preferential recording from either side of the head of human subjects in obtaining auditory brainstem responses using both monaural and binaural stimulation. Various electrode configurations were analyzed. Auditory brainstem response waveform differences were found on the basis of electrode placement. This implies an optimal electrode configuration which negates effects of preferential recording without sacrificing accuracy. There appears to be binaural interaction in the auditory brainstem responses. Discovery of an optimal electrode configuration for human subjects may facilitate objective measurement of neural interaction at the brainstem by comparing binaurally evoked and summated monaurally evoked auditory brainstem responses.
Detecting ear dominance using auditory evoked potentials
Authors: Martin Fredricka , Efron Robert , Yund E. William
Published: October 2005

The ear dominance for pitch described by Elton and Yund [J. Acoust. Soc. Am. 59, 889–898 (1976)] has been previously detected only by psychophysical methods. The present report uses the P-300 component of the auditory evoked potential to identify the magnitude and direction of ear dominance. The method entails the presentation of a series of identical dichotic chords. Randomly interspersed in this series are binaural tones with a frequency somewhere between the left and right ear tones of the dichotic chords. A P-300 wave is generated only when the binaural tone's pitch is perceptibly different from that of the series of dichotic chords. The results of this method correlate well with psychophysical measures of ear dominance in the same subjects.
Effect of rib cage on the beam profiles of ultrasonic transducers
Authors: Savakus A. D. , Shung K. K.
Published: October 2005

In multidimensional echo imaging of the heart, the anatomy and motion of the heart structures can be observed by placing the transducer over the intercostal window. The ultrasonic beam may be scattered, reflected or refracted from its path by the ribs and soft tissues between them. Since beam distortion is directly related to the loss of resolution in pulse-echo imaging systems, an investigation of the effects of these intervening tissues on the ultrasonic beam characteristics may be useful for establishing criteria for selecting suitable transducers in clinical scanning procedures. In order to address this problem, an automated system for rapid mapping of transducer field based on a microcomputer has been developed in our laboratory. In this paper, we will present the initital results on our investigation of the beam distortions produced by the rib cage in terms of 3-dimensional display of the intensity contours at various distances from the transducer. Also to be discussed is the effect of transducer angulation in relation to the breast plate on the transmitted ultrasonic beam.
Piezoelectric ceramics characteristics and applications
Authors: Berlincourt Don
Published: October 2005

Piezoelectric ceramics have been used for a little over thirty years. The first piezoelectric ceramic was barium titanate and it is still used. The lead titanate ceramics were introduced about 1955 and quickly became the most widely used piezoelectric material. Compositions were developed for many specific applications, as the strength of ferroelectricity in lead titanate zirconate allowed major chemical modification. The development and characteristics of these materials are described, and applications are reviewed. Major emphasis is placed on consumer applications, as it is, these that account for the major business in piezoelectric ceramic materials. Other more specialized applications are reviewed briefly, and piezoelectric ceramics developed for these applications are discussed.
Piezoelectricity in thin film materials
Authors: Foster N. F.
Published: October 2005

The need for efficient ultrasonic transducers in the 100 MHz to several GHz frequency range, for materials studies and for microwave device applications, has stimulated the development of a number of transducer structures. Perhaps the most versatile of those has been the thin film piezoelectric transducer. Starting in the early 1960's with primarily longitudinal bulk mode transduction in CdS films, the piezoelectric thin film transducer technology has progressed over the years, through the controlled generation and detection of both longitudinal and shear waves in CdS films, to the similar use of the higher coupling ZnO films with parallel investigations using other materials—including ZnS, AIN, and LiNbO3. While most of the early work was directed towards bulk wave generation and detection, the more recent strong interest in SAW devices has encouraged the use of piezoelectric thin films, primarily ZnO, in this arena also. As in many newly developing fields, the experimental work (film fabrication and testing) has stimulated relevant theoretical studies, and a rather comprehensive understanding of piezoelectric thin film structure and behavior has now been developed for both bulk and surface wave applications.
Time delay spectrometry—An inquisitorial scrutiny of its value and use in architectural acoustics
Authors: Cable Cecil R.
Published: October 2005

Eight years of hands-on experience in the application of time delay spectrometry to the field of architectural acoustics suggests that this exciting measuring system produces no magic numbers and no pat solutions to architectural problems. It does make available hard data on the behavior of sound within any enclosure and on reflections from and transmission through acoustical boundaries. Under discussion will be the use of this data; in its maximization and limitations as related to architectural design, in the testing of acoustical enclosures and materials and as an unprecedented learning experience.
Thermal fluctuation of stereocilia require active mechanical tuning
Authors: Schweitzer Allan , Bialek William
Published: October 2005

Brownish motion of the hair cell stereocilia greatly exceeds basilar membrane displacement at the auditory threshold. Spatial correlation of this noise is shown to preclude spatial averaging as a means of improving the signal-to-noise ratio, and it is argued that an active, mechanical frequency selectivity of the stereocilium itself is required. A theory of such tuning, by means of mechanical feedback with a finite, nondispersive, delay is presented. This theory predicts certain finestructural features of the hair cell tuning curves, as well as a variation of tuning characteristics with intensity, anoxia, and temperature; comparison with experiment is discussed. A molecular basis for such a mechanism will be presented (Bialek and Schweitzer, these abstracts).
Quantum-mechanical theory of mechanical activity in stereocilia and muscle
Authors: Bialek William , Schweitzer Allan
Published: October 2005

Brownian motion of the hair cell stereocilia may be overcome by active mechanical tuning (Schweitzer and Bialek, these abstracts). The analogy between the active mechanical characteristics required for the stereocilium and those observed for asynchronous insect flight muscle is explored. It is argued that conventional models of muscle contraction cannot provide stereocilium tuning at the required frequencies, and in the presence of Brownian noise. A new, explicitly quantum-mechanical theory of the contractile process is proposed. This theory is shown capable of quantitatively accounting for generation of the “cubic difference tone,” and explains the coexistence of pure-tone linearity and two-tone nonlinearity in the ear. Direct experimental tests of this hypothesis will be discussed.
Integral- and differential-equation formulations of two-dimensional cochlear models with nonzero fluid viscosity
Authors: Christian Richard S. , Tubis Arnold
Published: October 2005

Several equivalent series expressions for the fluid Green's functions of a two-dimensional cochlear model are developed. These expressions may be used to easily obtain the results of M. M. Sondhi [J. Acoust. Soc. Am. 63, 1468–1477 (1978)] and, in addition, derive integral equations and approximately equivalent differential equations for cochlear macromechanics which incorporate the effect of fluid viscosity. The equations may be rapidly solved and give accurate results for both long-wave and short-wave regions of the basilar membrane displacement.
Interferometric measurement of basilar membrane vibrations in cats using a round window approach
Authors: Khanna S. M. , Leonard D. G. B.
Published: October 2005

Our earlier basilar membrane measurements in cats were made through a hole in the cochlear wall. Drilling the hole invariably produced extensive cochlear damage even when the drills were designed to be extremely quiet. Mechanical tuning curves obtained in these damaged cochleas agree closely in shape with those shown by Evans and Wilson [Science 190, 1218–1222 (1975)]. A round window approach was adopted to eliminate drilling. Cochleas were opened without producing any bleeding by the use of a microcautery. Round window cochlear microphonics and tone pip N1 responses showed that the damage produced to the cochlea was reduced to a minimum. Basilar membrane measurements in these cochleas will be shown.
Adenylate energy charge, phosphorylation state, and energy status of organ of Corti (OC) in ischemia
Authors: Thalmann I. , Marcus N. Y. , Thalmann R.
Published: October 2005

To calculate these adenylate ratios, we determined the levels of ATP, ADP, and 5′ AMP in guinea pig OC. Control values amounted to 15.8 ± 2.1 (SD), 3.9 ± 0.5, and 0.53 ± 0.07 mmoles/kg dry wt. respectively. Adenylate values were similar in inner and outer layers of OC. We could not confirm the results of Krzanowski and Matschinsky [J. Histochem. Cytochem. 23, 766–773 (1975)], who reported a decline of ATP in OC of 30.9% within 30 s of ischemia. We found that ATP is reduced only by 7.8% and 11.8% within 35 and 65 s of ischemia, respectively. The validity of our ATP dais is supported by a similarly slow rate of change (increase) of 5′ AMP—a far more sensitive indicator of metabolic stress. Likewise, the increase of ADP was not substantial. Energy charge, phosphorylation state, and energy status amounted to 0.88, 2.53 g wet wt/μmole, and 4.05, respectively. Within 65 s of ischemia these parameters were reduced by 8 (65)%, 30 (79)%, and 53 (92)%, respectively [in parentheses values for stria vascularis; Thalmann et al., Laryngoscope 88, 1985–1998 (1979)]. The significance of these findings is discussed. [Supported by NIH.]
Perceptions of low-frequency stimuli induced by direct electrical stimulation at the cochlea
Authors: Edgerton Bradly J. , House William F. , Doyle Karen J.
Published: October 2005

The perceptions of several listeners, whose auditory nerves were stimulated directly by electrical sinusoids and biphasic pulses varying from 5 to 80 Hz, will be reported. The patients' perceptions of low-frequency sinusoidal stimuli were found to be remarkably similar to the perceptions reported by normal hearing listeners for acoustic stimuli. Perceptual transitions were found at 12, 15, and 30 Hz. No vestibular responses were elicited by low-frequency stimuli. The obtained data provides some important information about the frequency region from 5 to 25 Hz, which continues to be a difficult frequency region to study acoustically due to the ambiguity of tactile cues.
Electrical stimulation of the cochlear nucleus in a human subject
Authors: Edgerton Bradly J. , House William F.
Published: October 2005

A patient requiring bilateral acoustic neuroma removal was implanted with electrodes in the ventral cochlear nucleus. Electrical stimulation was performed over six weeks. Thresholds for sinusoids from 50 to 4000 Hz were ⩽10 μA; frequencies above 10 kHz required 100 to 150 μA. Discomfort levels required about 35 μA at low and mid frequencies and 300 μA at high frequencies. Weber fractions for intensity were approximately 3% above 500 Hz and 17% at 90 Hz. Loudness growth functions for 250, 1000, and 2000 Hz stimuli were linear with a doubling of perceived loudness for each 3 to 4 μA increase in intensity. At 90 Hz, an accelerated loudness function was obtained. Experiments with direct analog speech stimuli suggested nasality and place of constriction as features used to discriminate consonants and vowels. The patient's sound perceptions with a House implant stimulator will be discussed.
Formant frequency discrimination in a subject implanted with an intracochlear stimulating electrode
Authors: White Mark
Published: October 2005

In a four-choice, vowel identification test, the implanted subject identified the spoken word in 50 to 60 percent of the trials. Experiments were conducted to determine which acoustic features were being utilized by the implanted subject. Pairs of steady-state synthesized vowels were presented to the subject. Both a discrimination test and a difference scaling procedure indicated that the subject could easily discriminate between synthetic vowels with different first formant frequencies. However, the subject had great difficulty in discriminating between synthetic vowels with different second formant frequencies when the first formant frequencies were identical. This result was found to be consistent with an identification task using natural vowels in a single word context. The errors made by the subject in a four-choice vowel identification task were analysed (error rate = 45%). When the subject made an error, he generally chose the word containing the vowel with a first formant frequency closest to the first formant frequency of the spoken word's vowel. The subject appeared to have no preference for vowels with a second formant frequency near the spoken vowel's second formant frequency.
Objective tonal tinnitus induced by noise exposure in chinchillas
Authors: Zurek P. M. , Clark W. W.
Published: October 2005

Although objective tonal tinnitus (OTT) is very common in normal-hearing humans, we have not found any such instances in ten ears of six healthy chinchillas. However, we have succeeded in inducing OTT in one chinchilla (while failing in several others) by exposing it to an octave band of noise centered at 500 Hz, at 95 dB SPL, for nine days. The OTT, which was not present immediately after exposure but was seen after 12 days of recovery, is found variously at either 4.6 or 5.8 kHz at an amplitude of 40 dB SPL in the occluded ear canal. Another noise-exposed chinchilla possessed an OTT at about 6.4 kHz but, because this animal was not tested prior to exposure, we can only surmise that the OTT was caused by the acoustic trauma. Histological examination of this latter ear showed a punctate but complete lesion of the organ of Corti near the cochlear location characteristic of the frequency of the OTT. Observations on the suppression of these OTT's by external sounds leads us to conclude that, as with humans, the vibratory source of these signals lies within the cochlea. [Work supported by NIH.]
Ultrasonically enhanced heat transfer in liquid helium
Authors: Carey R. F. , Rooney J. A. , Smith C. W.
Published: October 2005

The effects of 10-MHz ultrasound on heat transfer from a copper block in liquid helium were studied as a function of temperature and acoustic amplitude. The copper block was mounted in the dewar system with a PZT-4 10-MHz thickness-mode resonant transducer positioned perpendicular to its surface. The temperature of the solid was determined using carbon resistance thermometers whose resistance was measured with ac bridge and lock-in amplifier circuitry. A heater in the copper block was supplied with current to give heat fluxes in the range from 0 to 1.5 mW/cm2. Measurements were made for temperature differences up to 50 mK. In Hell for the temperature range from 1.4 to 1.6 K, the ultrasound had no effect on heat transfer from the sample for amplitudes up to the threshold for collapse cavitation. In contrast, ultrasound produces a significant increase in heat transfer in Heɪ. At a temperature of 2.64 K the effective thermal conductance increased linearly with increasing acoustic velocity amplitude reaching a value which was approximately 2.5 times that of the nonsonated values for a velocity amplitude of 0.8 cm/s. [The work was supported in part by the Air Force Office of Scientific Research.]
Diffraction of a finite amplitude ultrasonic wave in solids
Authors: Blackburn Bruce , Breazeale M. A.
Published: October 2005

In order to use the harmonic generation technique to measure the nonlinearity parameters of solids, one must determine the amplitudes of both the fundamental and the second harmonic of an initially sinusoidal ultrasonic wave. In our experiment performed at 30 MHz, a typical value of the fundamental amplitude is 1 Å with a second harmonic amplitude of 0.001 Å. Since interesting samples often are smaller than those in which the infinite plane-wave model is sufficiently accurate, we consider the effect of diffraction on the measurements. Ten transducers having diameters between 1.9 mm and 12.7 mm (∼10λ and ∼90λ) were used with the same [100] copper sample. The resulting data show that diffraction does influence the calculated amplitude with the smaller transducers. Interpretation of the data in terms of a nonlinear diffraction model is attempted. Theoretical considerations are discussed. [Research supported by the Office of Naval Research.]
Detection of ultrasonic static displacement in solids
Authors: Cantrell John H. , Winfree William P.
Published: October 2005

The solution of the nonlinear differential equation which describes an initially sinusoidal, finite-amplitude elastic wave propagating in a solid contains a static displacement term in addition to the harmonic terms. The static displacement amplitude is theoretically predicted to be proportional to the product of the squares of the driving-wave amplitude and the driving-wave frequency [R. N. Thurston and M. J. Shapiro, J. Acoust. Soc. Am. 41, 1112 (1967); R. B. Thompson and H. F. Tiersten, J. Acoust. Soc. Am. 62, 33 (1977); B. Perrin, J. Phys. (Paris) 40, C8-216 (1979)]. We report the first experimental verification of the elastic wave static displacement in a solid ([111] direction of single crystal germanium) and find agreement with the theoretical predictions.
Perceptual discrimination of rise and decay time in speech- and nonspeech signals
Authors: van den Broecke Marcel P. R. , van Heuven Vincent J. J. P.
Published: October 2005

In a number of languages, differences in the decay time of vowels have been claimed to contribute to the perception of phonemic contrasts. In contrast with many other acoustic parameters relevant to speech perception, the perceptual acuity for abruptness phenomena has hardly been subjected to systematic psychophysical investigation. Previous experiments [V. J. J.P. van Heuven and M. P. R. van den Broecke, J. Acoust. Soc. Am. 66, 1308–1315 (1979)] have demonstrated that the JND is about 25% for rise and decay time differences in tone and noise bursts. Further experiments on vowel-like signals seemed to demonstrate a superior accuracy for offsets as compared to onsets. However, interaction of these offsets with overall duration may have played a role. These experiments have been replicated in order to create full comparability of rise- and decay-time signal conditions with respect to overall signal duration. Results indicate that perceptual acuity for rise and decay time in complex harmonic signals, including vowel-like sounds, is essentially symmetrical and in the same magnitude of those earlier established for tone and noise bursts. Data will be presented and implications with respect to our earlier findings will be discussed.
Phonological constraints in speech perception
Authors: Massaro Dominic W. , Cohen Michael M.
Published: October 2005

An important question in speech perception research is whether or not listeners have information about the degree to which an acoustic feature is present in speech. Evidence from traditional experimental studies of categorical perception suggests a negative answer for some speech sounds. In the present experiments, listeners were asked for continuous rather than discrete judgments in order to provide a more direct answer to this question. Subjects were asked to rate speech sounds according to where they fell on a particular speech continuum. The continua consisted of stop consonants varying in place (/ba/ to /da/) or voicing (/ba/ to /pa/) or a vowel continuum varying from /i/ to /I/. The rating responses of individual subjects were used to test quantitative models of “categorical” and “continuous” perception of acoustic features in speech. [Work supported by NIMH.]
Pig latin remembered: Test of a recoding explanation for modality/recency effects in short-term recall
Authors: Tartter Vivien C. , Shand Michael A.
Published: October 2005

Four short-term recall experiments are described which test a new explanation [M. A. Shand (1980). Short-term Coding Processes of Congenitally Deaf Signers of ASL: Natural Language Considerations, unpublished doctoral dissertation, Linguistics Department, University of California at San Diego] of the modality effect for auditorally presented items. Experiment 1 measures ordered recall for digits presented in Pig latin (e.g., eethray, ourfay). Experiment 2 is a control condition in which the stimuli contain the same phonemes as the Pig latin stimuli, but the items are normal English (e.g., 1A, 2A). Experiments 3 and 4 are baseline conditions for normal auditory and for visual (orthographic) digit presentation. The results are discussed in light of the assumption that modality/recency effects will appear for stimuli which constitute primary linguistic input for a subject, regardless of modality, but will not for stimuli which are recoded into a primary system.
The effect of lexical uniqueness on phonemic restoration
Authors: Samuel Arthur G.
Published: October 2005

When part of an utterance is deleted and replaced by an extraneous noise, listeners typically report that the utterance sounded intact; they appear to restore the deleted phoneme. The present study investigated whether this illusion differs when only one word can legally be restored (e.g., when the “l” in “lesion” is replaced), versus when more than one (restored) phoneme will create an English word (e.g., when the “l” in “legion” is replaced). The data suggest that listeners are sensitive to this manipulation. Signal-detection analyses of the data indicate that this “lexical uniqueness” affects both true perceptual restoration and the bias toward reporting utterances as intact. Control pseudowords, created by splicing together pieces of the test words, showed no effects of the lexical uniqueness of their components, supporting the lexical basis of the effects found with the words. The results are used to postulate a model of the word-recognition process.
Perceived phonetic distance among a set of synthetic whispered vowels and fricative consonants
Authors: McManus Timothy J. , Klatt Dennis H.
Published: October 2005

Phonetically trained listeners were presented with pairs of 300-ms synthetic speech-like sounds and asked to estimate phonetic distance between members of a pair. The first sound, the reference, was always the same—a voiceless [ae]. A set of 33 other sounds were synthesized by making small changes to formant frequencies, bandwidths, or spectral tile of the reference. Results indicate that phonetic distance judgements are consistent with previous work on voiced vowels [D. H. Klatt, J. Acoust. Soc. Am. 66, S86 (1979)] in showing that small formant frequency changes caused the largest perceived phonetic distances. However, the new results differ in that (1) changes in first formant frequency had little effect (probably because first formant bandwidth increases associated with an open glottis cause a relatively indistinct first formant spectral peak), and (2) spectral tilt changes also influenced distance judgments (probably by turning some stimuli into fricative-like spectra). In order to check this latter hypothesis, the tape was played to a new group of subjects who were asked to indicate whether each stimulus was a vowel or a fricative. It was found that fricatives are heard when spectral tilt increases, or when third or fourth formant frequency changes result in a high-frequency energy concentration. [Work supported in part by an NIH grant.]
Standing-wave pressure ratio in the human ear canal
Authors: Stinson M. R. , Shaw E. A. G. , Lawton B. W.
Published: October 2005

The presence of an air column of uncertain size and shape in front of the eardrum makes it difficult to perform reliable measurements of eardrum impedance at frequencies greater than 2 kHz; the standing-wave ratio, however, is relatively insensitive to irregularities in canal geometry and so provides a better characterization of the eardrum at these frequencies. The standing wave patterns occurring between 4 and 10 kHz in the human ear canal have recently been surveyed in a group of 13 normal ears. These data indicate substantially higher values of standing wave ratio (between 18 and 25 dB at 8 kHz) than previously reported (typically 13 dB at 8 kHz). The resulting smaller values of eardrum absorption coefficient (between 20% and 40%) are more consistent with the known properties of the human eardrum (mass, size, vibrational patterns, etc.). These results are an important step towards understanding the mechanics of the human eardrum and middle ear.
Some observations on the contribution of formant transitions to the identification of fricative-vowel and nasal-vowel syllables
Authors: Dorman M. F. , Raphael L. J.
Published: October 2005

In a series of experiments we have assessed the interaction of friction noises and nasal resonances with formant transitions in determining phonetic identification. When the intensity of /s/-friction in “sink” is reduced to about −15 dB re: vowel intensity, listeners report “think”. Thus, a fricative noise heard as /s/-like in isolation is heard as /θ/-like when followed by a vowel of appropriate amplitude. To determine the interval over which transitions exert a domineering influence, we turned to nasal-vowel syllables and created stimuli with /m/-resonances of varying duration followed by formant transitions appropriate for alveolar place. At durations up to 100 ms listeners report /na/, while at longer intervals they report /mna/.
Susceptibility to spread of masking in normal and sensorineural hearing-impaired listeners
Authors: Hannley Maureen
Published: October 2005

To determine whether upward spread of masking is responsible for failure to identify stop consonant place of articulation, sensorineural hearing-impaired subjects grouped according to etiological basis of hearing disorder were tested on a speech and a nonspeech task. Two-formant consonant - vowel syllables varying along a /b d g/ continuum were presented for identification at moderate and high intensity when formant amplitudes were equal and when F1 amplitude was attenuated by 6, 12, and 18 dB. In the second experiment, noise-on-tone masking functions were generated using seven narrow bands of noise at moderate and high intensity. Upward spread of masking could be demonstrated in speech and nonspeech tasks, irrespective of the subjects' age, audiometric configuration, or etiology of hearing impairment. Attenuation of F1 produced varying results on phoneme labelling performance among groups. The outcome of these experiments showed that while listeners with noise-induced hearing loss showed substantial improvement in identifying place of articulation when F1 was attenuated, upward spread of masking does not consistently account for poor place identification in other types of sensorineural hearing impairment.