bluuebunny/crossref_metadata_2025 huggingface dataset:
Annoyance of aircraft noise in relation to background noise
Authors: Kondo S. , Hayashi C. , Kodama H.
Published: October 2005

The effect of background noise level on the subjective response to aircraft noise was investigated. PAANI [Psychological Assessment of Aircraft Noise Index: developed by us—J. Acoust. Soc. Am. 63, 815–822 (1978)] has proved to be a good indicator and the detail will be mentioned. Other indicators—WECPNL, an energy mean, or a median value of maximum peak levels during the specified period—were studied as well. Some of them may be fairly good indicators of aircraft noise when levels are high enough relative to the background noise, but they fail to represent the subjective response when the background level is a factor in the evaluation.
Aircraft noise adaptation
Authors: Dempsey Thomas K. , Cawthorn Jimmy M.
Published: October 2005

An aircraft noise adaptation model is being developed at Langley Research Center to account for the variability in the responses of subjects participating in noise experiments. The principal concept of the model is a measured “aircraft adaptation level” which represents a noise annoyance calibration for each individual. The model assumes that annoyance response is a function of the interpretation of an aircraft noise by a person relative to his frame of reference or aircraft noise adaptation level. Psychoacoustic investigations were conducted at laboratories in Virginia and New York City as well as a noise survey of residential communities surrounding John F. Kennedy International Airport for development of the model. The results indicated that measured aircraft adaptation level (calibration) can help explain response variability but these levels themselves are not predicted by either attitude-personality indices collected from each individual or aircraft/street noise impact information collected from a person's residence. Furthermore, the annoyance responses of subjects did not vary as a function of the noise environment (aircraft/street) of a person's residence. Thus, group differences of annoyance responses were traced to the selection of subjects from different geographic areas rather than from different aircraft noise impact areas.
On the loudness of road traffic noise of longer duration (20 min.) in relation to instantaneous judgment
Authors: Kuwano S. , Namba S.
Published: October 2005

The relation between instantaneous loudness and overall loudness of 20-min road traffic noise was studied. Instantaneous loudness was obtained by the method of continuous judgment by category, which we have developed for this purpose. The results are as follows: (1) Instantaneous loudness was highly correlated with the sound level (dBA) at each moment. (2) Overall loudness showed high correlation with Leq. (3) The average of instantaneous judgment was smaller than overall loudness. This fact suggests that we are apt to ignore the parts of lower level when we judge overall loudness. The average of instantaneous judgment to 30 dB down duration from the peak level was found to agree with overall loudness.
A consideration on the loudness of impact sound
Authors: Kumagai M. , Kobayashi S. , Sone T. , Nimura T.
Published: October 2005

In order to investigate loudness of impact sound, the data of about thirty samples of impact sound in our daily life, were collected in prior to laboratory experiments. As the results of the analysis of these sounds, the following ranges were observed: peak level: up to 130 dBA; rise time (from start of a sound to its peak): 0.3–30 ms; decay time (from peak down to −20 dB): 5–500 ms. Referring to these findings, we designed an impact sound generator. In the experiments the effects of these factors on loudness of model impact sounds were studied by the use of the method of adjustment. The peak level of 80–100 dB, the rise time of 0.5–20 ms/60 dB and the decay time of 60–1000 ms/60 dB were treated as the experimental factors. As the results, PL dB, calculated from the peak level r.m.s. circuit with τ = 4.0 ms and 1/3 oct. band energy level was found to be an appropriate unit for loudness evaluation, and the energy of a single burst, Len, was a simple and good measure, too. [Work supported by the Ministry of Education.]
Characterization of power plant noise by coherence technique
Authors: Ying S. P. , Baki K. R. , Dennison E. E.
Published: October 2005

When the total output power is stimulated by statistically independent multiple sources through paths with linear behavior, the coherence function can be used to resolve the total power into individual output power for each source. This technique was applied to power plants for identification and characterization of multiple noise sources inside the plants. A dual channel fast Fourier transform analyzer was used to calculate the coherence function and their coherent output power. Several series of coherence measurements were made between the output sound level in each area and the potential noise sources, such as air seal blowers, condensers, condenser vacuum pumps, and coal pulverizers. These measurements quickly determined the degree of influence of each source and the frequency spectrum which was attributed to each piece of equipment. It was found that most of the noise sources had dominant frequency ranges, with sound levels up to 120 dBA at 1 m from the surface of equipment.
Estimation of acoustic power of flow-generated noise within silencers
Authors: Obata T.
Published: October 2005

The experimental apparatus consists of a 500-mm diameter dissipative muffler which is lined with sound absorbing materials of 200 mm in thickness. Air is supplied from a 700-W blower through a heater which is capable of heating the air up to 60°C. The measurements of SPL were made using a 30-mm-diameter microphone according to the hemispherical traverse which covered approximately 300 mm from the tail-pipe axis. The PWL of flow-generated noise are calculated from the these SPL values. The experimental results show that the acoustic power depends primarily on Mach number. The sound energy generates higher-frequency components in proportion to the 6–7th power of the mean flow velocity. The PWL increases with increase of the expansion ratio of cross-sectional area and of the diameter of the tail pipe, and it decreases with increase of the length of the chamber. The power spectrum of noise generated within silencers can be determined from the geometrical parameters of the silencers and mean velocity of air flow.
Normal mode solutions for the scattering of elastic waves from spherical solid inclusions
Authors: Flax L. , Überall H.
Published: October 2005

The nature of the resonances that occur in the acoustic-wave scattering from elastic bodies has been investigated [L. Flax, L. R. Dragonette, and H. Überall, J. Acoust. Soc. Am. 63, 723 (1978)] using the classical formalism of nuclear (Breit-Wigner) scattering theory, and similar studies have been made for the scattering of elastic waves from fluid-filled cavities in solids [A. J. Haug, S. G. Solomon, and H. Überall, J. Sound Vib. (in press); G. C. Gaunaurd and H. Überall, J. Acoust. Soc. Am. (in press)]. In a similar fashion, and following a previous study of elastic-wave scattering from solid inclusions [L. Flax, J. Acoust. Soc. Am. 62, S32(A) (1977)], we investigate the possible resonances produced in spherical solid inclusions by the scattering of dilatational and shear elastic waves. [H. Ü. is supported by ONR, Code 421.]
Surface waves and modal resonances in the scattering of dilatational waves from fluid-filled spherical cavities in solids
Authors: Gaunaurd G. C. , Überall H.
Published: October 2005

We extend our previous resonance formalism for the scattering of compressional waves by fluid-filled spherical cavities in (visco) elastic solids [G. C. Gaunaurd and H. Überall, J. Acoust. Soc. Am. 63, S40(A)(1978), and J. Acoust. Soc. Am. 63, 1960 (1978)] by analyzing the partial-wave amplitude resonances both as a function of frequency (or ka) for a given mode number, and as a function of (continuous) mode number n, at a given frequency. In both cases, the resonances have been isolated by subtracting an appropriate non-resonant background. The frequency analysis leads to a unique identification of the resonances in both the summed backscattering amplitudes. The mode number analysis leads to an interpretation of the scattering mechanism taking place around the cavity in terms of Regge poles (surface or creeping waves) whose trajectories in the complex n-plane, and associated dispersion curves for the phase velocities, are obtained and displayed. Extensive numerical results are obtained for various combinations of materials such as water-filled cavities in aluminum, or air-filled cavities in robber. [H. Überall is also at Catholic University, and was partially supported by ONR, Code 421.]
Scattering of acoustic waves from randomly rough surfaces
Authors: Numrich S. K.
Published: October 2005

Measurements have been made of sound scattered in the specular direction by fixed rough surfaces. The surfaces used were physical realizations of computer generated topographies which corresponded to Gaussian distributions in height to within specified limits. The RMS heights and correlation lengths of the two selected surfaces are 0.124 and 0.74 cm for the coarser surface and 0.021 and 0.305 cm for the finer surface. Each surface was milled into both brass and aluminum blocks. Measurements were made in water using 0.5-, 1.0- and 2.25-MHz transducers. Transient pulse analysis techniques were used to provide information about the scattered pulse over a wide range of frequencies. The dependence of the scattered return on incident angle, the sound speed in and density of the scattering material, the RMS height and the number of correlation lengths insonified is investigated. Comparisons are made with several theoretical models including a multiple scattering model. The scattered field is also illustrated by means of schlieren visualization.
Distribution of ions in cochlear tissues: Effects of noise exposure
Authors: Ryan Allen , Wickham M. Gary , Bone Robert C.
Published: October 2005

To assess the role of altered ion distribution in noise-induced hearing loss, the element content of isolated outer hair cells (OHCs), stria vascularis and spiral ligament was studied utilizing the energy dispersive X-ray analysis (EDXA) mode of the scanning electron microscope. In the normal chinchilla inner ear, EDXA spectra from non-nuclear regions of OHCs showed high levels of Cl and K, with relatively low P, S, and Na. OHC nuclei were similar but with high P. In contrast, both non-nuclear and nuclear regions of stria vascularis were characterized by high P and K, with Cl and Na significantly lower than in OHCs. The element content of the spiral ligament varied in a regular manner with the location sampled. Exposure to a two-octave (1414–5656 Hz) band of noise for 1 h at intensities from 90- to 120-dB SPL had no effect upon the element content of stria. OHC spectra were also unchanged in intact cells. Degenerating cells showed elevated Cl and K levels. The results suggest that changes in the ionic content of OHCs and stria vascularis are not involved in the temporary effects of noise. However, altered ion distribution does appear to be associated with the degeneration of OHCs after intense sound exposure.
AC cochlear potentials in an animal model for human atherosclerosis: Relationships to blood pressure, vascular disease, and blood coagulation
Authors: McCormick James G. , Hartley C. Bryce , Harris David T. , Ens Gordon E.
Published: October 2005

We have discovered an animal model, the white carneau pigeon, which for the first time, through its use in laboratory experiments, has demonstrated significant correlations between the magnitude of inner ear electric potentials and standard measures of blood pressure, blood cholesterol, and blood coagulation. Also, we have found that a new blood coagulation research tool—the sonoclot machine—can demonstrate blood coagulation physiology parameters which correlate highly with cochlear potentials in our animal model. The above results will be discussed in relation to our previous findings of relationships of atherosclerosis to hearing in the same animal model. [Work supported by NIH Grant Number NS-12013.]
Fast time domain solutions of a two-dimensional cochlear model by FFT methods
Authors: Allen J. B. , Sondhi M. M.
Published: October 2005

In an earlier paper [Allen, J. Acoust. Soc. Am. 61, 110–119 (1977)], a linear integral equation for a two dimensional cochlear model was formulated and solved using frequency domain methods. Sondhi [J. Acoust. Soc. Am. 63, 1468–1477 (1978)] then showed that the integral equation could be expressed in a symmetric form. In this talk, we show how this equation may be expressed as a circular convolution. As a result, it may be solved in the time domain, using fast Fourier transform methods, in less than 50 msec/time step. Since the solution is found in the time domain, nonlinear damping [Hall, J. Acoust. Soc. Am. 61, 802–810 (1977)] may be included as a trivial extension. As a further extension, we have included logitudinal BM stiffness in the apical turn in an attempt to account for the decrease in the high-frequency slope of neural tuning curves at lower frequencies.
Transmission line model of cat basilar membrane
Authors: Hind J. E.
Published: October 2005

The model was derived by changing the parameters of the nonlinear model of J. L. Hall [J. Acoust. Soc. Am. 61, 802–810 (1977)] who kindly provided his computer program. The static value of the resistance was varied to achieve a systematic decrease in Q from base to apex [M. M. Gibson et al., in Psychophysics and Physiology of Hearing, edited by E. F. Evans and J. P. Wilson (Academic Press, London, 1977) pp. 58–68]. The amplitude-vs-SPL characteristics was based on additional Mössbauer data on squirrel monkey basilar membrane recently analyzed by W. S. Rhode [unpublished], and, as in the model of H. G. Nilsson and A. R. Moller [Biol. Cybernetics 27, 107–112 (1977)], the Mössbauer results can be more closely approximated by having the nonlinear resistance term increase more slowly as a function of membrane velocity than the square-law relation used by Hall in the paper cited above. [Work supported by NIH and Univ. of Wisconsin Graduate School while author was on research leave at Tokyo Medical and Dental University; the assistance of Prof. K. Murata and his staff is gratefully acknowledged.]
Two-tone interactions in a nonlinear model of the basilar membrane
Authors: Iso Y. , Sakamoto H.
Published: October 2005

Combination tones and two-tone suppression are studied in a nonlinear electric circuit model of the basilar membrane. A cubic difference tone component, 2fL − fH = fCT (fL < fH), can be cancelled over all the sections apical to the fL's characteristic place, by adding a third input of fCT with an appropriate amplitude and phase. Effects of primary input levels and of primary input frequency intervals upon the cancellation levels are very similar to the results psychophysically obtained by Goldstein. Two-tone suppression is simulated as follows: in addition to the first input of frequency f1 and of level L1, the second input of constant level L2 and of variable frequency f2 is applied, and the voltages at the characteristic place of f1 are measured. Average values of rectified voltages are used as the approximate quantities proportional to firing rates of cochlear nerve fibers. Marked suppression is observed in the frequency region higher than f1. Suppression is also found in the lower frequency region, although in very slight degree.
Two-tone distortion products in a model of single auditory nerve fibers
Authors: Luetkenhoener B. , Hoke M.
Published: October 2005

The generation of distortion products in response to two-tone stimuli is one of numerous nonlinear phenomena as observed in the spike discharge patterns of single auditory nerve fibers. The mechanical to neural transduction has been cited as one possible source of these distortions. In the present paper we studied the distortion products generated in a mathematical model of an auditory nerve fibre based upon the Bonhoeffer-Van-der-Pol system of differential equations, which is a simplification of the well-known Hodgkin-Huxley system. Our model transforms arbitrary analogue inputs into a spike train. To account for spontaneous activity a Gaussian Noise is added internally. The model which is realized on a general purpose computer has been investigated for several two-tone stimuli. Analysing the model output by means of period histogramms we could detect besides others the cubic distortion product 2fL − fH. The results are compared with the known properties of primary auditory neurons and those of other nerve fibre models. [Work supported by Deutsche Forschungsgemeinschaft.]
Two-Tone suppression areas in the chinchilla auditory nerve
Authors: Harris D. M. , Ingvarsson K.
Published: October 2005

Frequency Threshold Curves (FTC) and two-tone supression (2TS) areas have been determined for single, primary fibers. 2TS is defined as a 20% or greater decrease in the firing rate evoked by a tone at the unit's characteristic frequency (CF) 10 dB above CF-threshold associated with the addition of a second variable tone. The shape and size of 2TS areas vary systematically as a function of fiber CF. The low side 2TS areas (second tone below CF) are located outside the limits of the fiber's FTC for high CF units and within the boundaries of the FTC for units with CF of approximately 3 kHz and below. With our criterion, low side 2TS areas are rarely found for low CF units (less than 2 kHz). Whole-nerve AP tuning curves collected with a forward masking procedure and AP supression areas collected with an unmasking method are similar to the single unit data for probe frequencies above about 4 kHz. Below 4 kHz, AP supression areas are smaller than their unit counterparts. Forward masking AP tuning curves are consistently broader than single unit FTCs.
Two-tone suppression in auditory nerve of the cat: Effect of excitatory f2
Authors: Javel Eric
Published: October 2005

Jayel et al. [J. Acoust. Soc. Am. 63, 1093–1104 (1978)] analyzed two-tone suppression effects when the excitatory tone (f1 is higher in frequency than the suppressor tone (f2). They concluded that suppression is observable when both f1 and f2 are excitatory and that its magnitude is related in part to the cochlear distance between the traveling wave maxima for the two tones. We extend these observations here to include cases where f2 < f1 as well as f2 > f1 with f2 excitatory. Temporal analyses of phase-locked discharge patterns of low-CF neurons indicate that suppression not only exists when f2 is excitatory for both f2 < f1 and f2 > f1) but also that (a) suppression magnitude may exceed 60 dB under appropriate conditions and (b) suppression magnitude declines in an orderly manner as f2 is removed in frequency from f1. For a given suppressor-tone intensity, however, the decline of suppression magnitude with increasing frequency separation is quantitatively different for f2 < f1 than it is for f2 > f1. [Work supported by a Biomedical Research Development Grant from NIH.]
Differences in auditory nerve fiber responses in regard to inner and outer hair cells
Authors: Nomoto M. , Maekawa M.
Published: October 2005

Single unit recordings were made from auditory nerve fibers in the monkey to pure tone stimuli. Extensive studies of frequency response areas suggested the existence of two types of auditory nerve fibers. One type showed a flat-bottomed response area and the other showed a conventional sharp one. On the other hand, curves plotting the discharge rate versus the intensity of the sound stimulus at various frequencies indicated two clear tendencies. In crossed ramp type fibers, the curve around the characteristic frequency (CF) showed a slow inclination, while the other curves showed a steep increment. In parallel ramp type fibers, the curves showed the same steep tendency. By the above two criteria, a total of 118 units could be divided into 40 and 78 unit groups which seemed to correspond to the outer spiral fiber and the inner radial fiber respectively. The entire distribution of Q(10) of the auditory fibers was the sum of the two log-normal distributions with different natures where Q(10) = CF/bandwidth at 10 dB above threshold.
Fatigue of the cochlear nerve by intense pure tones: Invariance of the half-octave shift
Authors: Meikle M. B. , Lee C. A.
Published: October 2005

In earlier work it was shown that pure tone overloads at 3, 6, and 12 kHz produced maximal neural depression at 1/2 octave above the exposure frequency [C. Mitchell et al., J. Acoust. Soc. Am. 53, 326 (1973)]. The present experiments were designed to determine whether or not the exact frequency at which maximum depression occurs is dependent upon the intensity of the exposure. Summated action potentials (APs) of the cochlear nerve were measured in guinea pigs before and after exposure to intense pure tones. These frequency-specific APs were elicited by carefully-shaped tone bursts (10 msec duration, 1 msec rise-decay) at 32 frequencies at 1/8 octave intervals between 2.1–30 kHz. Exposure frequencies were in the range 3k–20 kHz; exposure levels ranged from 85–120 dB; and durations ranged from 0.5 to 20 min. Regardless of exposure frequency or intensity, the maximum depression of AP occurred at 1/2 octave above the exposure frequency. In addition, recovery was observed over intervals as long as several hours and was found to be slowest at the half-octave above the exposure. The implications for mechanical events underlying cochlear transduction and fatigue will be discussed. [Supported by NINCDS.]
Suppression of auditory nerve discharges by a contralateral stimulus
Authors: Murata K. , Tanahashi T.
Published: October 2005

Single-unit activity was recorded from the cochlear nerve of cats immobilized by Flaxédil. The ipsilateral ear was just above threshold; the contralateral stimulus was the same except the intensity was varied. Most neurons responded to strong contralateral tones as well as to the ipsilateral stimulus. When the stimuli to the two ears were presented simultaneously the response clearly showed direct mechanical interaction between the two sounds in the ipsilateral cochlea. In addition, for a few neurons an intense contralateral stimulus suppressed more or less completely the response to ipsilateral sound as well as the spontaneous activity. The latency and time course of suppression and recovery from it were too slow to be due to monaural two-tone suppression, but seemed to resemble those of the inhibition induced by electrical stimulation of the crossed olivo-cochlear bundle beneath the floor of the 4th ventricle.
Deconvolution of auditory-nerve action potentials
Authors: Grandori F. , Fabbro M. , Minguzzi D.
Published: October 2005

The compound Auditory-Nerve Action Potential may be described as the convolution between the number of the eighth-nerve fibers activated by the incoming stimulation and the single unit action potentials as seen at the gross electrode. The technique of the deconvolution may be adopted to process the measured Action Potential as a basis to retrieve information about the cochlear activity, in terms of excitation distribution along the cochlea. Since the final results are influenced by the waveshape of the unit potential adopted, this aspect will be discussed in detail. Data from human and guinea pig cochleas, in normals and in pathological ears are presented and compared. In many pathological conditions the time course of the excitation distribution were significantly altered with respect to the normative data, while the alterations seen in the Action Potential waveshapes were not easily recognized. The intrinsic limitations of this technique, i.e., the uncertainties in the determination of the unit potential, are discussed with respect to the possibility of retrieving reliable information about the activity of regions with characteristic frequencies lower than 2 kHz in the guinea pig and in man, at least for high and intermediate intensity levels.
Off-effect in tone-burst evoked cochlear responses
Authors: Grandori F. , Boeri C. , Silva A.
Published: October 2005

The whole-nerve Action Potential (AP) and the single unit Post Stimulus Time histograms have been extensively investigated in relation to click stimulation and the on-response provoked by a tone-burst, but the off-response has never been studied in detail and no interpretation is available for these phenomena. The growth of an off-effect in the whole-nerve AP and in the single fiber discharge pattern at the end of a tone-burst is explained by means of some fundamental laws of the system dynamics. The available knowledge of the mechanisms of generation of the AP is sufficient enough to predict the dependence of the magnitude and of the shape of the off-AP on the burst paradigms (frequency, amplitude and phase). Simulations of a simple single fiber model are shown to predict off-responses with tone-bursts and sustained stimulations. On this basis, it is suggested that a better understanding of the single unit behavior is achieved by reproducing the model predictions by specially designed animal experiments.
Interactions of two types of neurons in the DCN
Authors: Voigt H. F. , Young E. D.
Published: October 2005

Neurons in the dorsal cochlear nucleus (DCN) of unanesthetized, decerebrate cats can be classified as type II/III (excited at all levels by best-frequency (BF) tones) or type IV (inhibited by moderate and high level BF tones). Many properties of type II/III neurons are consistent with the hypothesis that they are inhibitory interneurons on type IV cells [Young and Brownell, J. Neurophysiol. 39, 282 (1976); Young, J. Acoust. Soc. Am. 63, S76 (A) (1978)]. In order to study functional relationships between these types, pairs of DCN neurons were recorded simultaneously using single microelectrodes. Interleaved spike trains were separated on-line, and each neuron was classified type II/III or IV. For some pairs, complete frequency-intensity response maps were obtained. Cross correlograms of driven activity of type II/III-type IV pairs, obtained using stimuli which excited the type II/III and inhibited the type IV neuron, showed a decrease in the type IV's discharge rate following type II/III firings. This result is consistent with the hypothesis stated above. [Work supported by NIH.]
Digital simulation of vowel processing in the peripheral auditory system
Authors: Greenberg Steven
Published: October 2005

The response of the peripheral auditory system to digitally generated and human-articulated vowels was modelled at the level of the cochlea and auditory nerve. The simulation operates upon the spectral density function to derive an estimate of the excitation pattern of the VIIIth nerve and thereby serves to illustrate the manner in which certain acoustic attributes of the vocalic signal such as fundamental frequency, formant pattern, formant bandwidth, and glottal pulse shape affect the simulated discharge pattern of the auditory nerve. [Research supported by NIH.]
Possible reconstruction of auditory signals by the central nervous system (CNS)
Authors: Altes R. A.
Published: October 2005

Tuned auditory neurons and behavioral sensitivity to the envelopes of neuronal responses rather than to phase-locked discharge patterns [W. M. Siebert, Proc. IEEE 58, 723–730 (1970)] suggest that the CNS receives a spectrogram-like representation of acoustic stimuli. How much information about the original input signal u(t) is preserved in such a representation? The spectrogram is the convolution of the signal's time-frequency energy density function eu(t,f) with that of the filter which is used to construct the spectrogram [M. H. Ackroyd, J. Acoust. Soc. Am. 50, 1229–1231 (1971)]. By using two-dimensional deconvolution, eu(t,f) can be obtained from the spectrogram. The signal's auto-ambiguity function Xu(τ,φ) is the two-dimensional Fourier transform of eu(t,f), and u(t)exp(jλ) can be obtained from Xu(τ,φ), where λ is an arbitrary constant [W. M. Siebert, MIT, Q. Prog. Rep., 90–94(1958)]. If the spectrogram model is valid, these observations imply that the CNS can, in principle, completely reconstruct the input signal except for an unknown constant that is added to the phrase of u(t). It follows that u(t) and u(t) exp (jλ0) should be monaurally indistinguishable for any λ0.
Further observations on cochlear after-potentials
Authors: Durrant J. D.
Published: October 2005

The make-up of the cochlear after-potential (PAP) and the influence of the temporal characteristics of the sound stimulus on this response were reported previously [J. Acoust. Soc. Am. 63, S53 (A) (1978)]. To further illuminate the nature of this little known response input-output and frequency response characteristics of the PAP were examined in the first and third turns of guinea pig cochleas. The cochlear microphonics, summating potentials, and (in some instances) whole-nerve action potentials also were recorded for purposes of comparison. The peak magnitude of the PAP, specifically the positive component, tends to occur at or above the characteristic frequency of the site of recording, although the magnitude of the PAP is not sharply frequency dependent. The growth of the PAP with increasing intensity is typically much slower than the other cochlear responses. Besides contributing further to an impression of autonomy of the after-potentials from the other cochlear responses, the results of this study demonstrate that the PAP can be elicited by a wide range of stimuli and are widely distributed in the cochlea. [Work supported by DRF.]
Topics on speech waveform coding activities in Japan
Authors: Tomozawa A. , Ochiai K.
Published: October 2005

Topics on ADPCM and ADM technique developments in Japan are described. First, an ADPCM code sequence optimization method by K. Fushikida is discussed for an ADPCM with an adaptive quantization and fixed predictor. The method uses a technique reminiscent of dynamic programming and optimizes code sequence. It is shown that about 2-dB SNR improvement is obtainable for speech at 32 kbps (4 bits/sample). Second, another ADPCM technique by T. Araseki and K. Ochiai is described. This technique is suitable for use at the bit rate less than 32 kbps. Two adaptive predictors connected in a cascaded form are used. One of the predictors has an ordinary small number of prediction taps. However, the other predictor possesses a considerably large number of predictor taps which are used to predict speech waveform in one pitch period apart. A backward adaptive prediction technique with a gradient method is used for each of the two adaptive predictors. Finally, performance improvement techniques and LSI implementation by A. Tomozawa and K. Niwa are described for a discretely variable slope 32 kbps ADM (DVSD).
Predictive and residual encoding of speech
Authors: Makhoul John , Berouti Michael
Published: October 2005

This paper surveys recent developments in adaptive predictive coding (APC) of speech. Prominent among these developments are the use of a three-point pitch predictor, entropy coding of the residual, and adaptive shaping of the quantization-noise spectrum. The tradeoff between noise spectral shape and output signal-to-noise ratio is explained. APC systems produce high quality speech at around 16 kb/s; their quality diminishes rapidly at 9.6 kb/s or less. For those lower data rates, some form of voice-excited or residual-excited system becomes necessary. In such systems,. a low-frequency baseband is transmitted. The high-frequency regeneration of the excitation spectrum from the baseband is of special importance. Traditional regeneration techniques have used some form of nonlinear distortion of the baseband. followed by spectral flattening. We introduce a new set of promising regeneration techniques, where the results of the regeneration can be manipulated easily by the designer. Various hybrid configurations will also be discussed.
Practical implementations of speech waveform coders for the present day and for the mid-1980's
Authors: Goldberg A. J.
Published: October 2005

This paper will discuss practical implementations of speech waveform digitizers for the pre-1980 and post-1985 time periods. Based on requirements of expected mathematical complexity, accuracy, and redundancy of these coders, the basic hardware speeds and amount of logic to implement them will be given for today's implementations. Issues important to the commercial and military users will also be examined to ascertain how they can radically alter the architectures and hardware chosen for implementation. Then assuming that the speech digitization algorithms remain at least as complex as today's techniques, well-known procedures for forecasting LSI improvements and cost reductions will be used in estimating the hardware needed to implement these systems in the mid-1980's.
Propagation of N waves
Authors: Nakamura A. , Oie S.
Published: October 2005

The change of slope with propagation distance at zero crossing of the pressure profile in an N waveform is discussed, especially for its physical meaning in comparison with repeated sawtooth waves, probably random noise propagation, and even sine waves. While the propagation velocity of the shock fronts in the N waveform is different from the velocity of the fronts within the repeated sawtooth waveform, the change of the slope with the propagation distance is expressed by the same formula for both waveforms; that is, the straight-line segments propagate with the velocity of the finite-amplitude sound waves, for the energy of the wave is dissipated and the propagation velocity in the medium dispersed, depending upon the frequency. Changing slope is also discussed.
Droplet motion induced by N waves
Authors: Temkin S. , Mehta H. H.
Published: October 2005

An experimental facility that is capable of producing N waves of varied strength is described. The facility is used to study the response of small water droplets to the passage of N waves, but may also be used to study properties of N waves. The droplets have diameters ranging from 85 to 600 μm, and the N waves have strengths ΔP/P in the range 0.05–0.5. For small values of these parameters, the droplets do not deform, but move in response to the waves. The induced displacements can be used to obtain some information about the forces that act on small spheres under highly transient conditions. Preliminary measurements show that none of the presently available theoretical predictions for such forces is valid in those conditions. [Work supported by NSF Grant ENG 76-15045.]
Measurement of nonlinear reflection of N wave at the open end of a circular pipe
Authors: Nakamura T. , Nakamura A. , Takeuchi R.
Published: October 2005

The measurement of reflection of N waves at the open end of a circular pipe with baffle were made for the analysis of nonlinearity of energy reflection dependent upon shock amplitude. We simulated the pressure profiles on the time axis of the N wave impinged and reflected at the open end from the pressure profiles observed at a position in the pipe away from the open end. The simulation was done taking account of the propagation behavior in a pipe with wall effects and nonlinear effect. The nonlinear reflection of energy was discussed by means of integration Fourier spectrum of waves at the open end obtained by the simulation. The deviation of the observed value from the linear theory was found for a large-amplitude N wave.
Propagation of high-intensity impulsive sounds in air generated by the wire explosion. (Transition of wave form and frequency spectrum.)
Authors: Watanabe Y. , Urabe Y.
Published: October 2005

The waveform transition of high-intensity impulsive sounds due to the sound propagation in air was studied. An impulsive sound generated by the wire explosion was used as a point source. [Y. Watanabe and Y. Urabe, 9th ICA N34, Madrid (1977)] The measurements were carried out some points (0.3–30 m) away from the sound source. At the measurement points near the sound source, the waveforms of sound showed very steep rising up. With the increase of the distance from the sound source, the rising of waveform gradually became blunt, and pulse width also began to increase. It was thought that the above results were caused by the diversion of energy to higher-frequency components due to the nonlinearity of finite-amplitude sound.
Subjective attributes that influence judgments of digital transmission quality
Authors: McDermott B.
Published: October 2005

The ultimate test of the success of a digital technique for speech transmission is the quality of the speech as evaluated by unbiased listeners. The variety of methods for digital encoding, as well as the numerous design parameters for each method, have produced many new and different types of degradations in the transmitted speech signal. The identification and relative importance of the subjective attributes associated with each type of codec is a necessary step in understanding the quality of the reproduced speech signal. If particular atributes can be associated with certain design parameters, the relationship can provide valuable information to the design engineer. The manner in which the various attributes are combined and weighted by listeners serves as a guide for establishing the validity of objective measures to predict overall subjective quality.
Objective measures for speech quality testing
Authors: Barnwell Thomas P. , Voiers William D.
Published: October 2005

This paper presents a discussion of the philosophy and practice of speech quality testing using objective measures. The emphasis in the paper is on the problems of designing effective objective quality measures and the inherent limitations of such measures. Both traditional and recent techniques are discussed, along with the issues of implementation and evaluation. Experimental results on the correlation between objective quality measures and subjective quality measures are also presented.
Theoretical reflectivity and simulation of reflection from the ocean bottom
Authors: Fryer Gerard J.
Published: October 2005

The boundary value problem to be solved in computing the reflectivity of a solid, viscoelastic, ocean bottom can be formulated as a matrix differential equation with variable coefficients. In the Thomson-Haskell techniques a solution is found by assuming the coefficients (elastic parameters) are constant over a certain depth range (a layer). If high-velocity gradients are present a very large number of layers may be required for convergence, leading to prohibitive computer costs. A Runge-Kutta modification of the technique yields considerable savings in computer time. The improved technique is illustrated by computation of the full reflectivity function, in frequency-wavenumber space, of a turbidite sequence overlying basement. Synthetic pressure records obtained by two-dimensional transformation of the reflectivity function, were analyzed as if they were field-recorded data to attempt to recover the reflectivity. This exercise emphasizes that plane-wave reflectivity is defined only in frequency-wavenumber space, that any reflectivities estimated by treating energy return from the bottom as a specular reflection in the time domain must be erroneous. [Work supported by ONR.]
The temporal characteristics of seismic phases Pn, Sn, and T at large distances
Authors: Sutton G. H. , Duennebier F. K. , McCreery C. , Walker D.
Published: October 2005

Aside from the SOFAR channel of the world's oceans, the high-frequency Pn, Sn waveguide appears to be the earth's most efficient acoustical wave guide. Comparison of the characteristics as a function of time and location of Pn, Sn, and T phases recorded on hydrophones and seismographs on the ocean bottom indicates similarities that suggest that a multipath (eigenray) analysis similar to that used successfully for interpretating SOFAR signals might be used to refine our ideas concerning the generation and propagation mechanisms of Pn and Sn and to improve our knowledge of the lithospheric waveguide.
Investigation of the conditions for the existence of a leaky Rayleigh wave
Authors: Mayer W. G. , Brower N. G. , Himberger D. E.
Published: October 2005

The Rayleigh wave, an inhomogeneous surface wave, exists for all isotropic elastic solids. When the free surface of the solid is bounded by a liquid, a leaky Rayleigh wave, or inhomogeneous damped interface wave, may exist. In the limit that the density of the liquid goes to zero, the leaky Rayleigh wave tends to the free Rayleigh wave. However, the leaky Rayleigh wave does not exist for all liquid/isotropic solid systems. A well-known condition for the existence of the leaky Rayleigh wave is that the velocity of sound in the liquid must be less than that of the shear in the elastic solid. Upon investigation of the secular equation for the leaky Rayleigh wave velocity, other necessary conditions for existence become apparent. The conditions are influenced by the density ratio and the ratios of the various velocities in the liquid/solid system. [Work supported by ONR.]
Dichotic pitch extraction: Spectral limits of the contribution of the two ears to the dichotic pitch
Authors: Divenyi Pierre L.
Published: October 2005

A binaural complex consisting of two dichotically presented tones close in frequency will have a pitch different from that of either component presented monaurally. The object of the present experiment was to study the pitch of the binaural complex as a function of both interaural intensity difference and the bandwidth of one of the dichotic components. The dichotic stimulus consisted of a 100-ms burst of narrow-band noise centered at 1700 Hz and of a simultaneous, 100-ms pure tone having its frequency fixed either at 1650 or 1750 Hz. Using a modified Method-of-Adjustments procedure, the listeners matched the pitch of various dichotic tone-noise complexes to that of a binaural tone of variable frequency. Results indicate that the effective bandwidth of the monaural components contributing to the pitch of such complexes corresponds to that of the Critical Band. Relevance of the data to a central pitch processor theory will be discussed. [Work supported by the Veterans Administration.]
Lateralization factors and cerebral dominance
Authors: Craig J. D.
Published: October 2005

Human right- and left-handed subjects listened to dichotic four-beat rhythm patterns of five sinusoidal tones consisting of three quarter notes and two consecutive eighth notes. The eighth-note beat was the “signal”, and the stimuli to each ear differed only in the location of the signal in the measure. Subjects reported both the location of the signal(s) within the measure and the ear in which they heard it. Neither handedness group identified the ear in which the signal occurred with better than chance accuracy. However, right-handed subjects attributed a significantly greater number of signals to the right than to the left ear, regardless of ear of stimulation. Left-handed subjects attributed approximately equal numbers of signals to each ear. The data suggest that many previous studies of cerebral dominance and lateralization show the compound effects of the acoustical attributes of the stimuli and differential cerebral processing. It may be possible to design experiments to study the effects of differential cerebral processing of patterned auditory stimuli independent of lateralization due to the acoustical attributes of those stimuli.
A comparison of the effects of hearing impairment and acoustic filtering on consonant recognition
Authors: Walden B. E.
Published: October 2005

The relationship between consonant recognition under conditions of acoustic filtering and hearing loss was studied in subjects with unilateral hearing impairments. Using a procedure involving suprathreshold loudness balance between ears, a multifilter was used to match the (suprathreshold) audiometric configuration of the impaired ear. Consonant recognition data were obtained from the impaired ear and from the normal ear listening through the multifilter. To the extent that consonant recognition was similar in the two ears, the effect of the patient's hearing impairment on phoneme identification could be related to the audiometric configuration. A comparison between consonant recognition scores for the impaired ears and for the ears listening through the multifilter revealed large individual differences among subjects. These differences appeared related, in part, to the audiometric configuration. Mean consonant recognition ability, however, was almost always lower in the paired ear. In general, the more flat the audiometric configuration, the more dissimilar the consonant recognition between the two ears.
Improving the accuracy of airborne transmission loss evaluations through the intercomparison of performance tests
Authors: Jones R. E.
Published: October 2005

An analysis of transmission loss (TL) data from seven North American Laboratories was organized by ASTM Committee E-33.05 to study ASTM E-90 accuracy performance for single- and double-leaf partitions. Several mass law expressions are reviewed and compared with TL data from seven laboratories for four different limp-mass panel materials. It is noted that the laboratory TL data is not as linear with frequency as generally assumed, and examples are found where TL variation from mass law exceeds that suggested by E-90 precision requirements. In addition, an interlaboratory difference of 2 dB was found for some laboratories. For double-panel walls, TL data from three laboratories for similar constructions (STC > 50) showed unexpectedly large variation in TL (up to 14 points) and in STC (up to 6 points). Using double-panel theory, these TL differences are explained on the basis of interlaboratory differences in mass law and flanking (perhaps due to the test frame liners). A TL performance test series is illustrated with recent data from two laboratories and suggested as a basis for improving laboratory TL accuracy.
Acoustical privacy for closed office design
Authors: Wyerman Barry R. , Moulder Ron
Published: October 2005

Tests were conducted to determine the degree of sound isolation between a closed two-room pair of offices with a common ceiling and partition. Several ceilings were tested with a standard metal stud office partition with Fiberglas insulation and 1/2-in. gypsum wallboard. Ceiling STC ratings for each system were compaired to SPP > 70 requirements, according to PBS C.1 and C.2, for speech privacy in closed plan offices. Subjective tests were also conducted with a background masking sound system to determine its effect on speech privacy between offices. The objective of this work was to determine if speech privacy can be obtained in adjacent closed offices without an STC > 40 ceiling board provided that an adequate masking sound system is installed.
Electronic noise masking in open plan offices
Authors: Eisner M.
Published: October 2005

Open plan offices suffer in most instances from the lack of background noise levels being high enough to obtain effective speech privacy even in areas at some distance from a speaker or group of speakers. One method of providing comparatively low cost reliable noise masking is to install electronic noise masking systems in the office spaces. The objective of such systems is to provide even sound levels and sound spectra shaped to provide effective masking for most types of disturbing noise. Numerous installations in Europe, North America, and Australia has resulted in general acceptance to this approach. A case study is presented for a typical multi-story building with a general description of equipment used and expected reaction of occupants given. Comments by consultants who have had some experience with the systems is included.