bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal time structures of formant damping and excitation
Authors: Fant Gunnar
Published: October 2005

The frequency and rate of decay of a formant oscillation is known to be influenced by the pitch synchronous variation in glottal impedance. Multiple excitation within the voice period adds to the variability. Furthermore, the residue of the glottal pulse adds substantially to a nonuniform pattern of zero crossings in the speech wave. Because of different degrees of dependency on glottal damping, formants exhibit vowel and mode specific contours of the decay of the envelope. Time domain calculations based on Laplace transforms bring out the relative role of various factors and focus on the voice pulse residue as a component equivalent to a formant. Changes of the relative balance between the vocal pulse residue and formant oscillation within a voice breath group are discussed. Experiments on the perception of nonuniform decay provide a basis for defining equivalent bandwidth.
Production and perception of Mandarin tones with respect to vowel duration
Authors: Tseng Chiu-yu
Published: October 2005

The role of duration in the production and perception of Mandarin Tones has been investigated. All four tones produced in isolation and natural running speech have been analyzed by means of sound spectrographs and computer implemented measurements. The duration of vowel [i:] in high level tone alone varies from 110 ms to 450 ms. Computer edited stimuli have been generated of the “same” vowel with different durations and presented in a perception test. Duration does not affect the perception of high level tone, although the recognition of the vowel might be significantly reduced. Thus for high level tone in Mandarin vowel [i:], duration affects neither the production nor the perception of the overlaid tonal contour. More complicated interactions occur with respect to other vowels and other tonal contours.
Combinations of timing factors in speech production
Authors: Port Robert F.
Published: October 2005

This study explores the ways in which linguistic timing factors combine in the production of English and tests the model of Klatt [J. Acoust. Soc. Am. 59, 1208–1221 (1976)]. In two experiments the tensity feature of a stressed vowel and the voicing of the following stop were changed along with a variable altering the length of the VC syllable. The duration of both the stressed vowel, V, and the following stop closure, C, were measured. In the first experiment either one or two unstressed syllables were added to the word and in the second speaking tempo was changed. The significant results of both experiments are accounted for with a formal timing model that separately specifies (1) the Vm + C duration (where Vm = the mean duration across both vowels) depending on the number of syllables or tempo, (2) the ratio Vm/C depending on the voicing of the stop, and (3), as a final ordered step, a rule adjusting vowel duration by a constant ratio depending on the tensity of the vowel. This integrated model accounts for (1) the “incompressability” effects of prosodic features, (2) constant ratio combination of segmental features and (3) the constant V/C ratios for values of the voicing feature comparable to those found in perception experiments.
Relationships among pitch-intensity functions and some other pure-tone pitch anomalies
Authors: Burns Edward M.
Published: October 2005

Monaural pitch-intensity functions were obtained in both ears of observers at half-octave frequencies from 250 to 2000 Hz. For a given subject, the form of individual pitch-intensity functions was often nonmonotonic and usually different in the two ears. Predictions derived from these pitch-intensity functions were compared with several pitch-shift phenomena, including amount of binaural diplacusis (as a function of intensity) and pitch shift of a tone in the presence of a higher intensity tone (as a function of frequency/intensity differences and phase). The latter phenomenon was compared under the assumption that the reduction in masking effectiveness of the lower intensity tone, caused by the presence of the higher intensity tone (as deduced from nonsimultaneous masking measurements), is equivalent to a reduction in intensity. Data from the binaural diplacusis measurements agreed well with the predictions derived from the pitch-intensity functions. [Research supported in part by an NIH postdoctoral fellowship; portions were performed at the Research Laboratory of Electronics, MIT.]
Directivity of polyhedral loudspeaker arrays
Authors: Soom A. , Koo E.
Published: October 2005

Known analytical solutions of the sound fields around some elementary sources have been combined in numerical models for the purpose of calculating the directivity of three-dimensional arrays of such elementary sources. The elementary sources considered are the monopole, the baffled piston, and the oscillating cap in a solid sphere. Results based on the analytical models have been compared with directivity measurements taken on a 12-sided polyhedron with single and multiple loudspeakers mounted on its surface. Good correspondence was found between calculated and measured directivities for loudspeaker diameters less than the acoustic wave-length. The oscillating cap in solid sphere proved to be the most useful elementary source model for calculating directivity over a wide frequency range. Implications to the design of isotropic arrays are discussed.
Survey of ultrasound medical applications, Canada 1977–1978
Authors: Benwell D. A.
Published: October 2005

A Canada wide survey of the diagnostic, therapeutic, and surgical applications of ultrasound in medicine was conducted in the Fall of 1977. A total of 4154 questionnaires were sent to 1341 hospitals, 1887 chiropractors, 300 physiotherapists, and 726 sports medicine clinics. 62% of the questionnaires were returned, 40% of these completed. The comprehensive questionnaire provides information on the type of equipment used, the operator qualifications, the patient exposure, the number of patients treated, and adverse effects. Statistics of the results of the survey will be presented. The survey is believed to be the most detailed study undertaken to date of the use of ultrasound in medicine, and the results will be of interest to all ultrasound regulatory bodies and physicians working in the field.
Growth of difference tone level [L(f2−f1)] with input level as a function of f2/f1
Authors: Humes L. E.
Published: October 2005

The level of the simple difference tone [L(f2−f1] arising from a two-tone input (frequencies: f1 and f2, f2 > f1; levels: L1 and L2) was estimated in four normal-hearing listeners using a nonsimultaneous gap masking technique. Parameters studied include: f1 (800 and 1550 Hz). f2/f1 (1.08 to 1.61), and primary level (L1 varied, L2 fixed; L1 fixed, L2 varied; L1 = L2 varied). The growth of L(f2 − f1 as a function of primary level was found to be affected by f2/f1. For L1 = L2, for instance, L(f2 − f1) growth rates of approximately 1.0 dB/dB were obtained for small f2/f1 values (f1/f1 ⩽ 1.16), whereas growth rates of roughly 2.0 dB/dB were observed for larger f2/f1 values (f2/f1 ⩾ 1.41). For L1 or L2 varied separately, L(f2 − f1) grew at a rate of 1.0 dB/dB throughout the range studied (L2/L1 or L1/L2 = −15 to + 15 dB) for large f2/f1 (f2/f1 = 1.41). For small f2/f1 = 1.08 or 1.16), however, L(f2 − f1) grew at a rate of 1.0 dB/dB for L1 < L2 or L2 < L1 and at a rate of less than 1.0 dB/dB (0.4 to −0.4 dB/dB) for L1 > L2 or L2 > L1. [This work was conducted while the author was a predoctoral fellow in the Audiology Program, Northwestern University.]
Applying an interactive graphics system to underwater acoustics modeling
Authors: Cornyn J. J.
Published: October 2005

A growing trend in underwater acoustics modeling is toward the use of more interactive and time-dependent graphics displays. Two approaches to achieving CRT graphics are the graphics terminal and the graphics system. Since a graphics terminal requires the power of the host computer for all graphics applications, it cannot operate independent of the host computer. A graphics system, on the other hand, contains its computer and thus can operate independent of the host computer. In addition to providing all the advantages of a graphics terminal (except cost), a graphics system can be used for stand-alone creation, time-dependent display, and manipulation of graphic information, digitization, program text and document editing, compilation, execution, printing, and hardcopy plotting. In addition, it contains its own file management system and allows for the transfer of program and data files between the host computers and graphics system. This paper describes the application of an interactive graphics system to some underwater acoustics problems.
Preliminary evaluation of a computer model for the solution of underwater parabolic wave equations
Authors: Lee Ding , Botseas George , Papadakis John S.
Published: October 2005

The development of a computer model based on numerical ordinary differential equation methods (ODE) for solving underwater parabolic wave equations is near completion. During the development period, the model has been tested by comparing its solutions with those of existing models. Limited comparisons with the fast field program (FFP) and a parabolic equation (PE) model based on the split-step Fourier algorithm have been made. Solutions to two classes of test problems were compared. The first class of problems satisfied all requirements of the split-step method. The second class dealt with strong bottom interactions. The ODE PE model produced accurate results for both classes of problems with favorable speed. [Work supported by NAVMAT and NAVSEA.]
Scattering of spherical impulses by slightly rough interfaces
Authors: Tolstoy I.
Published: October 2005

The effect of multiple coherent acoustical scattering by a perfectly rigid, slightly rough surface can be represented by a “small roughness” boundary condition due to Biot. Using normal coordinates, this allows one to obtain simple, closed form solutions for the scattering of spherical impulses, for either isotropic or anisotropic surface roughness [I. Tolstoy, J. Acoust. Soc. Am. (in press)]. These results can be extended to the case of rough interfaces between media of different densities. Of particular interest here is the possibility of a boundary—or surface—wave travelling along the interface, and of amplitude proportional to the logarithmic density increment between the media. [Work supported by ONR.]
A method for rating power seat adjuster assemblies for quality control tests
Authors: Saha Pranab , Baker Robert N.
Published: October 2005

A study was made to develop a method for conducting a quality control test to rate noisiness, or annoyance of power seat adjuster assemblies for passenger cars. Laboratory tests were conducted wherein 6 to 9 jurors inside a passenger car with the engine off operated 22 seat adjusters which were representative of the entire range of acceptability from very good to bad. Each of the adjusters was operated in all of the eight possible operating modes by each of the jurors. The jurors rated the seats in the 8 modes on a 1 to 10 scale with 10 being the noisiest, and 5 being the level of marginal acceptability. Sound and vibration measurements were simultaneously made at different locations to provide data which might be used to establish a correlation between the subjective and the objective measures of quality. Data thus obtained were analyzed to study the different intensity levels versus time of operation as well as frequency. The data analyses indicated that there was a definite trend of the increase of the juror subjective ratings with the increase of A-weighted sound level near the juror's ear to form a linear functional relationship. Statistical correlation was strongest for the noisiest operating modes. Correlation of subjective ratings with vibration levels was much weaker.
Development of a reference sound source calibration procedure
Authors: Mansbach Peter A.
Published: October 2005

Several studies were conducted with the goal of developing a calibration procedure for reference sound sources. In one of these, a series of 60 measurements was performed in the NBS reverberation room. These measurements emphasized the importance of source position, indicated that errors due to environmental variation can be controlled, and demonstrated that by averaging over three source positions, a transfer calibration can be performed with a precision of about 0.1 dB, for certain stable sources. In another series of tests, measurements performed in a free field over a reflecting plane were compared with reverberation room measurements. The free-field data are about 1 dB higher than the reverberation room data over the entire audible frequency spectrum, in addition to the well-known discrepancy at low frequencies. A possible explanation under investigation is the difference between the absorption effective for a steady-state signal and that measured conventionally.
Diffusion and the rotating diffuser in reverberant sound fields
Authors: Warshawsky M. S. , Tichy J.
Published: October 2005

In a perfectly diffuse sound field it is known that the spatial cross-correlation coefficient, R(kr), is given by R(kr) = sin (kr)/kr. A method based on the satisfaction of sin (kr)/kr in many directions is a strong indication of perfect diffusion. Measurements were conducted for pure tone excitation and the effect of a rotating diffuser on the measured spatial cross-correlation coefficient was investigated. The diffuser was rotated at six discrete speeds ranging from 0.0 to 5.0 rps in order that the effect of diffuser speed of rotation could be studied. Results indicate that the rotating diffuser can significantly improve the relative degree of diffusion in a room and the method presented provides a quantitative relationship between the diffusion and diffuser speed.
The importance of a threshold level when assessing noise annoyance
Authors: Gjestland T.
Published: October 2005

The energy equivalent continuous A-weighted sound level is widely used to describe the annoying effects of traffic noise. In many practical noise situations, however, the correlation between Leq and a subjective assessment may be rather poor. Only audible noise may contribute to the annoyance. We may therefore introduce a threshold level, and take into account only those periods when the actual noise level exceeds this threshold. Results from laboratory experiments, show that real noise situations with identical Leq may have different annoying effects. The differences may be explained by our threshold theory.
Precise control of the relative phases of two ultrasonic purses using digital logic circuitry
Authors: Mills John M. , Carolus Thomas H.
Published: October 2005

Description is given of a recently constructed device for use in ultrasonic experiments that employ two matched transducers. The device produces two sinusoidal bursts of substantially identical waveform, but with an adjustable delay between their starting times. The bursts are derived digitally from an external frequency standard (crystal clock), with a frequency of 5 MHz; the master frequency for sine wave synthesis can be any integer fraction of this clock frequency. The period of each cycle is ten times the reciprocal of that integer fraction of the master frequency. Any integer number of sinusoidal cycles, from one to nine cycles, are generated as a burst. A delay counter is started coincident with the sinusoidal waveform generator. Upon completion of this preset delay interval a second sine counter is started, which then generates the same number of cycles as there were in the first burst. The delay interval may be adjusted to any integer number of master clock cycles. Thus the two sine wave pulses can be delayed by any integer multiple of one tenth of a period of one sinusoid. The three-decade delay counter allows the total delay between the two pulses to be as much as 100 cycles. Sinusoidal output frequency, the number of cycles in a burst, and the delay between two successive bursts are all adjustable during the course of an experiment. [Work supported by NASA.]
SAW hydrophone
Authors: Das P. , Lanzl C.
Published: October 2005

A hydrophone which senses both absolute pressure and changes in pressure has been developed using a surface acoustic wave (SAW) delay line on a piezoelectric substrate. The pressure applied to the hydrophone is converted to a flexural loading of the piezoelectric plate which alters the surface wave velocity on the plate. This change in SAW velocity is measured as a change in the phase shift between the input and output signals of the delay line using a mixer and low-pass filter. The piezoelectric plate thickness and length and the center frequency of the interdigital transducer (IDT) can be chosen to optimize the sensitivity of SAW hydrophone. The SAW delay line is a planar structure, therefore, it is simple and inexpensive to manufacture. This paper presents performance data of a number of SAW hydrophones using delay lines having IDT at 50 100 and 200 MHz. Extensive measurements of sensitivity and frequency response have been made for delay lines fabricated on LiNbO3 and S-T-cut quartz substrates and compared with measurements obtained from commercial hydrophones in the same setup. It is to be mentioned that a SAW transmitting hydrophone can also be fabricated using a SAW delay line in the feedback loop of an amplifier to form an oscillator. However, if transmitting mode is unnecessary, extensive simplification can be achieved in the detector circuits using the phase detection described in this paper.
Absorption of ultrasound in protein solutions
Authors: Kremkau F. W. , Cowgill R. W.
Published: October 2005

Absorption coefficient and propagation speeds for aqueous solutions of globular proteins were measured at pH 7 and 290°K. Concentrations were approximately 100 mg/ml. Proteins measured were lysozyme, γ-globulin, myoglobin, hemoglobin, egg albumin, β-lactoglobulin, bovine serum albumin, and bacitracin. Specific absorption and propagation speed did not correlate with molecular weight, fraction of α-helix content, or n-mer structure. In addition, fibrous muscle protein paramyosin, and its subunit, PPC-1, were measured in α-helical and random coil state. The conformation change was produced with 6M quanidine hydrochloride. The ratio of α-helix state absorption to random coil state absorption was approximately two for PPC-I and six for paramyosin. [Work supported by NIGMS.]
Comparison of shifted sideband and conventional beamforming techniques
Authors: Mucci R. A. , Pridham R. G.
Published: October 2005

For many array configurations the exact time delays required for beamsteering impose prohibitingly large sample rate requirements on digital beamformer implementation. This necessitates the use of approximate time delays to achieve moderate sample rate requirements. For conventional beamformer implementations this degrades the sidelobe structure of the beampatterns. This degradation is also experienced by shifted sideband beamformers (SSB) which utilize frequency translated single sideband representations of the input signals [J. Acoust. Soc. Am. 64, S116(A) (1978)]. However, since beamsteering is performed on translated signals rather than on the original signals, degradation of the beampattern for the SSB is less sensitive to absolute time-delay errors than for the conventional approach. This result is supported analytically and by examples. The phase shift beamformer, a limiting case of both a frequency domain beamformer and the SSB, is considered. Beamsteering errors experienced by the phase shift beamformer at frequencies other than that for which it was designed are discussed. Analytical results and examples are presented which demonstrate that these errors can be eliminated with the SSB.
Context effects in the categorization of speech and nonspeech stimuli
Authors: Fujisaki Hiroya , Shigeno Sumi
Published: October 2005

It is a well-known fact that the categorical judgment on a stimulus is generally influenced by the context, but systematic studies on quantitative aspects of the context effect are rather few. The present study investigated the influence of the relative positions of the target and context stimuli both on the stimulus continuum and on the time axis. The influence of stimulus attributes was also investigated using pure tones, complex tones with a formant structure, and synthetic vowel sounds. The results indicated the existence of a gradual transition from assimilation to contrast in almost all cases studied, the contrastive effect becoming more intense with increased stimulus complexity in nonspeech stimuli and most intense in speech stimuli. An interpretation of the results is presented on the basis of a model for the process of categorical judgment. [Work supported by Grant-in-Aid for Scientific Research from the Ministry of Education.]
Are vowels in context really identified better than vowels in isolation?
Authors: Macchi M. J.
Published: October 2005

Strange, Verbrugge, Shankweiler, and Edman [“Consonant environment specifies vowel identity.” J. Acoust. Soc. Am. 60, 213–224 (1976)] reported that naive listeners misidentified approximately three times as many tokens of vowels spoken in isolation as the corresponding vowels in consonantal context. On the basis of these findings, they argue that the superior intelligibility of vowels in consonantal context is due to the fact that formant transitions, traditionally regarded as providing information about consonant identity, also provide perceptually significant information about vowel identity. The present study tested naive listeners identification of eleven American English vowels spoken in isolation and in consonantal context with an experimental design comparable to that used By Strange et al. Here, however, problems with the interpretation of orthographic symbols used to represent English vowels were minimized by having listeners identify the syllables by rhyming them with English words. The results of the rhyming test indicated that vowels in both contexts were identified with near-perfect (98%) accuracy. Further, the test did not reveal any difference in identifiability between the two vowel contexts.
A time-domain study of the stopped horn
Authors: Pyle Robert W.
Published: October 2005

Hand stopping, the partial occlusion of the horn bell by the hand of the player, was introduced in the 18th century as a means for altering the pitches of the notes produced by the valveless instrument of that day. Controversy arose over whether a stopped note was produced by flattening the open note above or by sharpening the open note below. In an earlier paper [Pyle, “Pitch change of the stopped French horn,” J. Acoust. Soc. Am. 36, 1025(A) (1964)], I approached this problem in the frequency domain by analyzing the resonance frequencies of the horn with and without the presence of the hand. In this paper I reconcile the “pitch rises” and “pitch falls” schools of thought with results obtained with a time-domain pulse-reflection technique.
Development and application of an analog model of a miniature hearing aid earphone
Authors: White Richard E. C. , Studebaker Gerald A.
Published: October 2005

It is well known that an electrical analog of an acoustic transducer can be developed by making measurements of the individual physical characteristics of the transducer's component parts. Some methods used to create and validate an analog of a miniature hearing aid earphone will be described. Results will be presented which show that although the model can mimic the general feature of the behavior of the earphone, there are also significant detail differences which can be analyzed to lead to further inferences about the operation of the real system. An application of the model in predicting the acoustic output of a hearing aid will be illustrated. [Work supported by NIH.]
The calculation of characteristic impedance and propagation operator associated with isothermal and viscous effects in acoustic tubes
Authors: Wheeler D. R.
Published: October 2005

Chebychev type approximations are used to represent the Kelvin functions and in turn the complex Bessel functions needed in modeling the characteristic impedance and propagation operator for an acoustic tube. This technique is used to approximate the Bessel functions of the first kind of order zero and order one with complex arguments. The method is then used to approximate the ratio of Bessel functions in an effort to decrease computing time. The results are used in electrical analog expressions for computing system frequency response of miniature transducers.
Numerical prediction of the dynamic response of a cylindrical shell in an acoustic medium
Authors: Giltrud M. E.
Published: October 2005

The transient response is predicted for an elastic cylindrical shell impinged upon by a plane acoustic wave in a fluid. The approach is numerical and in particular applies the USA-STAGS code which combines the finite element method for the structural analysis and the doubly asymptotic approximation (DAA) for the fluid-structure interaction. Several causes are analyzed, and the computations are compared to an exact solution [H. Huang, J. Appl. Mech. 37, 1091–1106 (1970)]. The agreement is very close, a fact which, in the situation considered, strongly supports the applicability of USA-STAGS to fluid-structure interaction problems, and more generally validates the DAA methodology.
Manner judgments affect the locus of the labial/dental boundary for stops and fricatives
Authors: Carden Guy , Levitt Andrea , Jusczyk Peter
Published: October 2005

We investigated place of articulation in labial and dental stops and fricatives using both natural and synthetic speech stimuli. Harris (1958) suggested that place perception for [f], [v], [θ], and [ð] is primarily determined by formant transition cues rather than by properties of the frication. Our results agree: with hers, but also show that perception of the formant transitions is affected by manner of articulation. Specifically, when the frication is removed from natural [θa] the truncated syllable is perceived as beginning with a labial stop [b] instead of the expected dental [d]. Experiments with synthetic stimuli confirmed that the labial—dental boundary was indeed further forward for fricatives than for stops. It is unlikely that this shift is caused by masking from the frication, since a parallel shift could be produced for both natural and synthetic stimuli by instructions to label the stimuli as fricatives even when no frication was present. Since perception of acoustically identical stimuli varied with the phonetic manner class to which they were attributed, we conclude that the effect is phonetic rather than psychoacoustic. [Supported by NICHD and NSERCC.]
Performance of an expert spectrogram reader
Authors: Cole R. A. , Rudnicky A. I. , Zue V. M.
Published: October 2005

The subject in our study has spent between 2000–2500 h learning to read speech spectrograms. We tested the subject's ability to identify the phonetic content of broadband speech spectrograms of unknown utterances during eight separate sessions of about 4 h each. The expert was presented with 23 spectrograms of English sentences and sequences of words and nonsense words, and 45 English words embedded in a known carrier phrase. The phonetic labels produced by the expert agreed with the phonetic labels produced by trained phoneticians (who listened to the speech) between 80% and 90% of the time, depending upon the scoring method used. When presented with words in a known carrier phrase, labeling performance improved to about 93%. A linguist who was presented with the phonetic transcriptions produced by the spectrogram reader was unable to identify all of the words in ten of 15 utterances, and missed only a single work in each of the remaining five. A film will be shown of the expert segmenting and labeling two spectrograms of unknown utterances.
Cochlear-microphonic versus hair-cell tuning in the cochlea
Authors: Kletsky E. J. , Zwislocki J. J.
Published: October 2005

Cochlear microphonics (CM) seem to arise primarily from the outer hair cells (OHCs) and have a much broader frequency distribution than do the receptor potentials of the inner hair cells (IHCs). Does the difference arise from the spread of the receptor potentials of OHCs, or are these potentials more broadly tuned than IHC potentials? We modeled the tuning of the IHC potentials on the assumption that it parallels the shear motion between the tectorial membrane and the reticular lamina. The obtained tuning curves agree with the experimental ones. To compute the CM at a given frequency, the model distribution of the receptor potentials is convolved with an exponentially decaying space function having a space constant of about 1 mm. The frequency distribution of model CM at a given location is derived by repeating the convolution at several frequencies and making a cut through the family of the obtained curves. The resulting CM tuning is much flatter than that of the IHC receptor potentials of the model and roughly parallels the basilar-membrane tuning below the best frequency. Above this frequency, the model distribution curve shows a plateau similar to that found in physiological CM measurements. [Work supported by NIH.]
Morphogenesis of the medial superior olivary neurons in the albino rat
Authors: Rogowski B. A. , Feng A. S.
Published: October 2005

The medial (accessory) superior olivary neurons receive bilateral inputs from the ventral cochlear nuclei and possess dendrites primarily extending laterally and medially, serving as a potential model for studying the plasticity of dendritic development. In this study, the morphogenesis of medial superior olivary neurons in albino rats was investigated. Rats were sacrificed at various ages, ranging from 12 to 60 days after birth. Brains were processed according to Golgi-Cox methods, with Cresyl-Violet counterstaining. The neurons were visualized with the aid of a camera lucida drawing attachment. Medial superior olivary neurons exhibited the following ontogenetical patterns: (1) the incidence of growth cones, filopodia, varicosities and filamentous processes decreased with progressive development; (2) cell body diameter diminished from a maximum size at day 20 to a more mature state; and (3) higher order dendritic branches emerged with age. These data suggest that the adult form of dendritic branching occurs as a result of an interplay between growth and differentiation of some processes into functional connections and the possible resorption of others. [Work supported by an NIH grant NS 14488.]
An approach to comparative anatomy and physiology of the auditory system
Authors: Adams Joe C.
Published: October 2005

Functional constraints on neurons imposed by morphology provide a basis for comparative considerations of neural processing. Rules regarding structure and function permit inferences regarding function of structures in species where physiological recordings are precluded. Globular cells of the auditory brainstem are a good example. These cells are found in several brainstem nuclei. Their structure in different nuclei as seen by many methods is similar. They have thin dendrites, large endings on their cell bodies, and their discharge patterns follow closely those of the large endings. Evidence is good that the globular cells of the ventral nucleus of the lateral lemniscus receive large terminals from octopus cells of the contralateral cochlear nucleus. Insight into the role of these cells in analyzing sound may be gained by comparing numbers of these cells in animals with different hearing capacities. Mice have few, echolocating bats (Optesicus) have many, whereas cats and some primates have intermediate numbers. Functional properties of these cells suggest that increasing numbers of cells across species reflects increasing abilities in discriminating transient acoustic events.
Lateral suppression in human brainstem responses
Authors: Stanny R. R. , Elfner L. F.
Published: October 2005

Five ms probe sinusoids with frequencies (fp) of 2.0 kHz and levels of 35 dB SL were forward masked by 17.5-ms tone bursts with frequencies (fm) equal to fp and and levels of 40 dB SL. A third, 60 dB SL, tone burst was presented simultaneously with the masker at frequencies (fv) equal to fm and at 16-octave intervals about fm. Amplitudes of wave V components of probe-evoked brainstem responses were enhanced by the addition of the variable-frequency tone at frequencies above fm, with the greatest amount of unmasking occurring when fv was set to 1.12 fm or 1.26 fm and little or no unmasking for values of fe of 1.41 fm or greater. The magnitude of the observed suppression, estimated by extrapolating from probe response amplitude-intensity functions, is in tolerable agreement with psychophysical suppression data obtained under the same conditions.
On the nonmonotonic behavior of cubic distortion products in the human ear
Authors: Weber R. , Mellert V.
Published: October 2005

The cubic difference tone (CDT) 2f1−f2 is measured by compensation as a function of the stimulus level L and of the frequency ratio f2/f1 of the primaries f1, f2 (f1<f2) in the 2−kHz region. Relative minima of the cancellation level LCT are observed for a certain range of the stimulus level L and the frequency ratio f2/f1 which can be regarded as a ’’region of existence’’ for these nonmonotonicities. No satisfactory explanation can be given for the observed nonmonotonic behavior of the CDT. In a second part some research is done on the quasicubic difference tone (QCDT) f1+f2−f3 that can be perceived under certain stimulus conditions if three tones f1, f2, f3 are presented to a normal human ear. Its dependence on the amplitude and on the frequencies of the primaries is comparable to the analogous behavior of the CDT. In particular, the QCDT f1 + f2 − f3 shows the same nonmonotonicity as a function of the stimulus frequencies as the CDT 2f1 − f2. From this similarity, it can be concluded that the nonmonotonic mechanism is not primarily dependent on the special excitation of the basilar membrane that is evoked by the primaries.

Subject Classification: 65.56.
Radiation−driven magnetoacoustic waves in a confined gas
Authors: Sarma L. V. K. V. , Sarma M. S.
Published: October 2005

Radiation−driven magnetoacoustic waves are studied in an electrically conducting and thermally radiating gas confined between two plane stationary walls which are placed perpendicular to the direction of one−dimensional motion of the gas. One of the walls provides a sinusoidal input of blackbody radiation and the other wall is a perfect reflector. Two types of damped harmonic waves are excited which form a system of standing waves traveling in the positive and negative directions. One of the waves is a magnetoacoustic wave and the second has attributes basically due to radiation. The effects of magnetic field on the pressure and velocity are examined. It is seen that the pressure and velocity decrease in a warm gas, i.e., for the moderate values of Boltzmann number. However, their response increases in a hot gas, i.e., for very small values of the Boltzmann number. The contributions to pressure and velocity due to the second type of waves are insignificant in a warm gas and further decreases with the increasing strength of the magnetic field. In the case of hot gas the contributions to the pressure response are significant.

Subject Classification: 28.50; 35.60.
Reply to ’’Comments on ’Level and zero crossings in volume reverberation signals’ ’’ [J. E. Ehrenberg and C. A. Erickson, J. Acoust. Soc. Am. 57 961–963 (1975)]
Authors: Spindel R. C. , McElroy P. T.
Published: October 2005

We discuss our approximation in treating the case of slightly non-Gaussian reverberation with narrow-band transmissions. We indicate that our empirical model for the zero crossing rate yields a good fit to field data.

Subject Classification: 30.40; 60.20.
Acoustic waves in ducts with sinusoidally perturbed walls and mean flow
Authors: Nayfeh Ali H.
Published: October 2005

An analysis is presented of the propagation of acoustic waves in a hard-walled duct with sinusoidally perturbed walls and carrying mean flow. The results show that resonance occurs whenever the wavenumber of the wall undulations is approximately equal to the difference between the wavenumbers of any two propagating modes. It is shown that neither of the resonating modes could exist in the duct without strongly exciting the other resonating mode.

Subject Classification: 20.45, 20.60; 28.60.
Monaural detection with contralateral cue. V. Interstimulus interval in MDCC and amplitude discrimination
Authors: Taylor M. M. , Smith S. M.
Published: October 2005

The effect of the interstimulus gap (ISG) between the two intervals of a 2IFC task was determined for MDCC tasks and for monaural and binaural amplitude discrimination, for ISG values ranging from 30 to 1000 msec. Increasing ISG improved performance, but differently depending on the task. For all tasks, there was a short latency period followed by a linear rise in (d′)2 followed by a period of asymptotic performance, as ISG was increased. For practical purposes, ISG values of 500 msec probably give near optimum performance except for untrained observers or for difficult listening conditions, in which cases 700 msec should usually suffice. The duration of the latency period depended strongly on task and observer. For MDCC tasks, there was a trading relationship between E/N0 and ISG. In amplitude discrimination, however, short ISG, or small E/N0 formed limiting conditions for which performance could not be improved by changing values of the other variable. The concepts of asymptotic efficiency, rate efficiency, and time efficiency were defined and used to demonstrate intraobserver consistency and interobserver differences across the various tasks.

Subject Classification: 65.75, 65.62, 65.58.
Temporal acuity as a function of frequency difference
Authors: Wier Craig C. , Green David M.
Published: October 2005

Several experiments are reported relating to the temporal resolving power of the auditory system. The experimental task was to discriminate between the two signals generated when a waveform was played either forward or backward in time (a condition in which the two signals have identical energy spectra). A two-segment waveform of total duration T was generated. The first T/2 segment was a sinusoid of one frequency and the second T/2 segment was a sinusoid of a different frequency. Each trial contained two observation intervals. In one interval the frequency change was from high to low, in the other interval low to high. As the total duration decreases discrimination becomes more difficult. It is nearly perfect for durations as short as 2 msec when the frequency of one segment is 1000 Hz and the other frequency 2000 Hz (ΔF=1000 Hz). For smaller values of ΔF, even at very short durations (4 msec), discrimination is about like that obtained in a simple frequency discrimination experiment.

Subject Classification: 65.70, 65.54.
Ambient noise level above plane with continuous distribution of random sources
Authors: Sutherland Louis C.
Published: October 2005

Extending an analysis previously developed by E. A. G. Shaw and N. Olson [J. Acoust. Soc. Amer. 51, 1781–1793 (1972)], it is shown that the residual noise level above a plane containing a continuous distribution of random uncorrelated sources decreases very slowly with elevation for typical values of an air-absorption coefficient. The analysis is applicable to measurement or evaluation of community noise over a wide area with the use of an elevated measurement position.

Subject Classification: 50.80, 28.45.
Acoustics and the concert hall
Authors: Beranek Leo L.
Published: October 2005

Frederick Vinton Hunt profoundly affected the course of architectural acoustics. As the de facto successor to W. C. Sabine, he began his acoustical career by utilizing the Sabine reverberation chamber at Harvard University in the early 1930s to introduce accuracy into reverberation-time measurements. Stimulated by P. M. Morse’s Chap. VIII in Vibration and Sound (1936), Professor Hunt explored the sound field in a rectangular, marble-walled box and published in 1939 a new means for measuring sound-absorption coefficients of acoustical materials as a function of angle of wave incidence and, in addition, the details of a high-impedance, research sound source. As a continuing step he, with his students, expanded the application of the normal-mode-of-vibration theory of acoustics to full-scale rectangular rooms in which acoustical materials were present on one or more walls. Although he subsequently developed research interests in other fields, his papers in architectural acoustics touched off scores of published works by his students and their colleagues. Examples of his contributions that can be found today include techniques for reverberation measurement, the meaning of sound diffusion in spaces, the design of auditoriums for speech and music, and the principles of audio reinforcement and reproduction. This paper summarizes the present-day status of concert hall design, with emphasis on those elements of architecture that must be controlled if satisfactory results are to be obtained.

Subject Classification: 10.60; 55.40.
Theory of air frame noise
Authors: Meecham W. C.
Published: October 2005

Air frame noise is examined using Curle’s theory for noise from rigid surfaces interacting with turbulence. Measured ’’air frame noise’’ often is open to question because of engine contribution. A large number of examples are considered: model airfoil in a jet, glider noise, jet wing in atmospheric turbulence, boundary layer noise on trailing wing edge, flat-generated noise, landing gear noise, noise from jet impinging on flap, and some others. Of all of these estimated noise sources it appears that for commercial jets the noises from jets on flaps (when present) and from landing gear may be the only sources of possible practical significance.

Subject Classification: 28.65; 40.55, 40.26; 50.55.
Ultrasonic absorption in air at elevated temperatures
Authors: Bass H. E. , Keeton Roy G.
Published: October 2005

The attenuation of a 1 MHz ultrasonic signal has been measured in 78%N2/22%O2 at temperatures of 302 °K, 467 °K, and 689 °K and pressures from 1 atm to 1/60 atm. The measured attenuation was corrected for classical effects to obtain the attenuation due to rotational relaxation. In addition, the total absorption has been compared to computed values based on a linear combination of viscous, thermal conduction, diffusion, and relaxation losses to check the constants used for each of these terms. The rotational relaxation time of the mixture was found to be 7×10−10, 10×10−10, and 21×10−10 sec atm at 302 °K, 467 °K, and 689 °K, respectively.

Subject Classification: 35.20, 35.35.
Perception of (Hindi) consonants in differentiated clipped speech
Authors: Gupta J. P. , Ahmad Arshad
Published: October 2005

Twenty nine initial consonants and 31 final consonants of CVC syllables were studied for perceptual confusions under the condition of differentialtion and infinite peak clipping. A quantitative procedure was used to calculate the percentage of information of each of the nine linguistic features (affriction, friction, nasality, aspiration, voicing, liquids, flapped liquids, continuants, and place), and the data so obtained were studied in relation to the data of the two previous studies [J. Acoust. Soc. Am. 45, 758–763 (1969) and J. Acoust. Soc. Am. 45, 770–773 (1969)]. It was found that liquids, voicing and continuants were more affected and that friction, affrication and place of articulation were less affected by the distortion of differentiation and clipping. The relative importance of features in differentiated clipped speech was not found to be the same as that of the normal speech. The study also indicated the perceptual difference between the two distortion conditions with and without pre differentiation.

Subject Classification: 70.30.
Headphone monitoring system for binaural experiments below 1 kHz
Authors: Domnitz R. H.
Published: October 2005

Binaural experiments are often confounded by variability in the acoustic coupling of the headphones. A simple and convenient system is described for detecting and electrically compensating acoustic imbalances while the headphones are worn by the listener. Application of the system in some binaural experiments is discussed.

Subject Classification: 65.80; 65.62; 85.76.
Force and electrical Thevenin equivalent circuits and simulations for thickness mode piezoelectric transducers
Authors: Martin Roy W. , Sigelmann Rubens A.
Published: October 2005

A simple model is reported for thickness-mode piezoelectric elements used as ultrasonic transducers in measurement systems. The model represents the excitation system and transducer as a Thevenin mechanical equivalent for the transmitting mode and a Thevenin electrical equivalent for the receiving mode. Computer programs based on the model have been developed, and computer simulations to study the effects of backing materials, element areas, and excitation sources are reported. The nature in which the source impedance alters the Thevenin mechanical output impedance and its importance in determining peak transmission frequency and in computing acoustic coating layers for matching was found. A total transfer improvement of 28 dB was shown for epoxy-backed elements radiating into fluid with the transducer used as both transmitter and receiver by using high values of source and load impedances in contrast to low values. The model was found to agree closely with experimental data of a 2.7-MHz transducer.

Subject Classification: 85.40; 80.70; 85.52.
Composite sandwich transducers with quarter-wavelength radiating layers
Authors: Ranz-Guerra C. , Ruiz-Aguirre R. Dominguez
Published: October 2005

The combination of the composite sandwich transducers general equation with a defined gain index suggests that, provided both backing and radiating layers are made of different materials, the optimum performance is obtained when (1) the transducer radiating head is a quarter wavelength thick, as it is known, and (2) the piezoelectric layer is of zero thickness. The last result implies that the optimum design cannot be reached; it can only be approximated by piezoelectric layers of small thickness. In this instance the Langevin’s equation is greatly simplified. Experimental data are presented to decide the limits of use of the simplified Langevin’s equation when the piezoelectric consists of PZT-4 ceramics. The outlined method can be of use in any active layer.

Subject Classification: 85.52.
Measurements of diffraction and interaural delay of a progressive sound wave caused by the human head. II
Authors: Abbagnaro Louis A. , Bauer Benjamin B. , Torick Emil L.
Published: October 2005

On several occasions the authors have required information on diffraction of sound and interaural time delay caused by the human head, and have measured these parameters in anechoic space. The measurements are of interest since both live subjects and a sophisticated acoustical manikin were used. These measurements are difficult to perform in a reliable fashion at high frequencies on live subjects because of head movement and use of the manikin allowed extension of most measurements to 10 kHz. Different measurement techniques were tried to yield accurate data, and these methods are discussed and results compared.

Subject Classification: 65.60, 65.62, 65.75; 20.30.