摘要:

A recent report of a series of dichotic listening experiments [Lauter, J. Acoust. Soc. Am.71, 701–707 (1982)] showed that although individual listeners differ in the ‘‘absolute ear advantage’’ shown for a given sound, there are patterns of ‘‘relative ear advantages’’ that are consistent across listeners. It was suggested that these patterns might provide a means of studying which features of test sounds are important in determining ear advantages. A survey of 12 earlier experiments, including a brief synopsis of procedures, results, and conclusions, followed by reanalysis of individual scores, shows that patterns of relative ear advantages were also present in earlier results, though obscured by an analysis that focused on the average listener. Examination of these patterns and the characteristics of sounds tested reveals a few acoustical features of sounds (e.g., event timing, bandwidth, number of dimensions changing with time) that seem to affect ear differences in a consistent way, from listener to listener and under a variety of experimental procedures. It is suggested that with attention to systematic manipulation of characteristics of test sounds, patterns of relative ear advantages may prove helpful in telling us more about the perception of complex sounds.

ISSN:0001-4966    

DOI:10.1121/1.389710

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The standing wave tube technique has been adapted to measure the acoustic internal source impedance of an internal combustion engine. In order to implement this technique an extensive experimental facility was designed and constructed and simple test cases were evaluated for validity. In addition an adaptation of the standing wave tube method incorporating a random signal as the external driver sound source and digital data analysis techniques were introduced to reduce the experimental difficulty and time consumption. Normalized specific acoustic impedance data at a constant engine speed of 2200 rpm show little change with varying engine load conditions. Similar data at a constant engine load condition of 254‐mm Hg exhibit more significant dependence on engine speed.

ISSN:0001-4966    

DOI:10.1121/1.389708

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Compact calcified tissues from a wide variety of species were used in a study of the dependence of sonic plesio‐velocity on physical parameters. A linear dependence of velocity on wet density has been found for each of three categories of wet mineralized tissue: compact long bone measured in the axial direction, compact long bone measured in the radial direction, and hyperpycnotic mineralized tissues. A similar linear dependency was found for dry calcified tissue using the dry density. In addition to these three parameters (density, orientation, and water content) two other factors were identified. The bone fibers in long bone matrix are ordered with respect to the bone axis and the anisotropy of long bone matches that of its matrix. There is no corresponding order to the fibers in hyperpycnotic tissue matrix. The fifth parameter is believed to be the porosity. Fish bone is much more porous than other compact bone from long bone and the sonic velocity in fish bone is much lower than for other bone. These parameters are not independent.

ISSN:0001-4966    

DOI:10.1121/1.389723

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Normal subjects learned to identify words through a tactile vocoder. The vocoder employed 16 filter channels, each with a bandwidth of 1/3 octave, with center frequencies ranging from 200–8000 Hz. The output of each filter was detected and after logarithmic amplification the resulting outputs were transmitted to a 16‐channel solenoid array placed on the subject’s ventromedial forearm. Words, spoken ‘‘live voice,’’ were used as stimuli; the subject was able to feel both the vocalizations of the reader and herself and, most importantly, extensive training was provided. In 40.5 h one subject learned 70 words and a second subject reached criterion on 150 words in the comparatively short time of 55 h. Words that were poorly identified initially were identified more readily with increased experience. Phonetic identification tests showed that the features of voicing, nasality, and frication were reliably recognized, indicating the tactile vocoder will be useful in providing information to complement lipreading. Finally, subjects learned rapidly to generalize word‐learning to unfamiliar readers.

ISSN:0001-4966    

DOI:10.1121/1.389685

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Previous research with speechlike signals has suggested that upward spread of masking from the first formant (F1) may interfere with the identification of place of articulation information signaled by changes in the upper formants. This suggestion was tested by presenting two‐formant stop consonant–vowel syllables varying along a /ba/–/da/–/ga/ continuum to hearing‐impaired listeners grouped according to etiological basis of the disorder. The syllables were presented monaurally at 80 and 100 dB SPL when formant amplitudes were equal and whenF1 amplitude was reduced by 6, 12, and 18 dB. Noise‐on‐tone masking patterns were also generated using narrow bands of noise at 80 and 100 dB SPL to assess the extent of upward spread of masking. Upward spread of masking could be demonstrated in both speech and nonspeech tasks, irrespective of the subject’s age, audiometric configuration, or etiology of hearing impairment. Attenuation ofF1 had different effects on phonetic identification in different subject groups: While listeners with noise‐induced hearing loss showed substantial improvement in identifying place of articulation, upward spread of masking did not consistently account for poor place identification in other types of sensorineural hearing impairment.

ISSN:0001-4966    

DOI:10.1121/1.389616

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

For noise which is spectrally modulated (ripple noise) as well as temporally modulated (the ripples move), the Spectro‐Temporal Modulation Transfer Function (STMTF) is defined as the curve relating modulation threshold to temporal modulation frequency with ripple spacing as a parameter. A white noise stimulus was spectro‐temporally modulated in the 0.2‐ to 1.0‐kHz region with a spectral modulation frequency (peak distance) of 0.2 kHz. Three types of temporal modulation were applied: the ripples rolled upward, downward, or the peaks and troughs interchanged periodically. It is shown that the STMTFs for these types are equal. So, for a ripple spacing of 0.2 kHz the spectro‐temporal modulation thresholds are independent of the type of temporal modulation. These STMTFs appeared to be low‐pass functions, no minimum was found. Their plateaus were at the same modulation depth as the modulation thresholds found by previous investigators who employed stationary ripple noise.

ISSN:0001-4966    

DOI:10.1121/1.389617

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Sets of level and phase data of the (2f1–f2)‐cancellation tone were measured with the same fit of the earphone. The results obtained were transferred into vector diagrams asx‐yrepresentations. Characteristic rules for the development of the cancellation tone can be extracted from a detailed analysis of such diagrams.

ISSN:0001-4966    

DOI:10.1121/1.389618

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Temporal gap resolution is measured with Békésy tracking procedure and filtered noise stimuli in the frequency range below 6000 Hz. Stimulus parameters include high‐pass and low‐pass cutoff frequency, band center frequency, bandwidth in a 2‐oct range, and signal level in the low‐to‐moderate intensity range. The pattern of results indicates that gap resolution improves with an increase in stimulus frequency in a manner that can be described by a linear function with a slope of about 2 ms/oct. This relationship applies to signal levels greater than 25–30 dB SL. A linear trend also describes gap threshold as a function of the empirical critical bandwidth within the same frequency range. Implications of the results for simple functional models of temporal processing are examined.

ISSN:0001-4966    

DOI:10.1121/1.389619

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

This paper reports further psychophysical studies on a multiple‐channel cochlear implant patient evaluating the feasibility of a speech processing strategy which converts the acoustic fundamental frequency to electric repetition rate, the second‐formant frequency to electrode position, and the acoustic amplitude to current level. The first four studies evaluated the use of a special pulse pattern to minimize the loudness variation with electric repetition rate. The chosen pulse pattern consisted of multiple pulses occurring in the first half of each repetitive period (MPP) in contrast to the more conventional pattern with a single pulse per period (SPP). The results showed that MPP approximately equalized the loudness variation with repetition rate. The dynamic range of current, the pitch variation with repetition rate, and the difference limens for repetition rate were found to be similar for MPP and SPP. Two other studies investigated interaction between electrode position and repetition rate (RR). The first of these showed that the patient could make use of information provided by rising or falling RR trajectories superimposed on individual electrodes or electrode trajectories as an indicator of the direction of intonation variation. The second of these studies showed that the dissimilarities amongst the hearing sensations produced by steady‐state stimuli differing in electrode position and repetition rate were characterized by two perceptual components, relating to the two electric parameters, respectively.

ISSN:0001-4966    

DOI:10.1121/1.389620

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The most commonly alleged experimental artifact associated with real‐ear attenuation at threshold (REAT) measurements of hearing protection devices (HPDs) was examined: Masking of the protected thresholds due to physiological noise amplified by the occlusion effect. An ear canal mounted subminiature microphone was used to obtain objective measures of physiological noise in occluded and unoccluded test conditions and of the insertion loss (IL) of insert, semi‐aural, supra‐aural, and circumaural HPDs when exposed to broadband noise with a sound pressure level of 93 dB. Measurements spanned 1/3 octave bands from 125 Hz to 2 kHz. Attenuation was also measured via a subjective REAT procedure and the magnitude of the occlusion effect was examined via bone conduction audiometry. The IL data confirmed the accuracy of the REAT results except at the lowest frequencies tested, where the degree to which the REAT values were spuriously inflated was quantified and found to be device related. Furthermore, the magnitude of the error (which never exceeded 5 dB) could be predicted by measuring the physiological noise in the occluded ear and calculating how much this would mask the occluded threshold. It was noted that no evidence was found in the data to suggest a dependency of HPD attenuation on sound level.

ISSN:0001-4966    

DOI:10.1121/1.389621

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP