摘要:

An ambient acoustic field is assumed to be observed through a delay‐and‐sum beamformer, in conjunction with a line array of non‐uniformly‐spaced sensors. The beamformer output power, as a function of steering direction, is related to the angular power density of the acoustic field through a certain integral equation, with the kernel being the known power response pattern of the array. In this note, we present the results of some computer experiments concerned with solving this integral equation by working directly in the angle domain, rather than in the wave‐number spectral domain. The method is general for any array, but is of interest mainly in the case of a non‐uniformly‐spaced array, to which our examples correspond.Subject Classification: [43]60.20, [43]60.30; [43]30.82.

ISSN:0001-4966    

DOI:10.1121/1.381028

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

In a laboratory experiment, human subjects were presented pairs of recorded 1‐min traffic sounds. Subjects chose whichever sound of each pair they thought they would rather be exposed to on a regular basis; they also judged the relative dissimilarity of the sounds in each pair. The data were analyzed using multidimensional scaling techniques. The choice data showed that relative aversiveness of the sounds was related mainly to their subjective intensity. The dissimilarity data showed that subjects distinguished sounds on the basis of both subjective intensity and information, independent of intensity, about the source of the sounds. The single physical noise measure most highly correlated with the subjective intensity attribute from both sets of psychological data wasLeq, the energy‐equivalent sound level. Several new measures of the shape of the average power spectrum, and of the time‐dependent variability in dBAlevels, failed to add appreciably to the predictive power ofLeqalone.Subject Classification: [43]65.75, [43]65.50; [43]50.70, [43]50.50.

ISSN:0001-4966    

DOI:10.1121/1.381029

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

The dependence of the absolute auditory threshold on signal duration was measured by means of behavioral methods in the house mouse (Musmusculus). Twelve frequencies between 1 kHz and 120 kHz and white broad‐band noise were tested while seven pulse durations between 1 and 3000 msec were used. In any case temporal summation follows the functionI⋅tb=const until, at a critical durationtc, a constant value is reached where thresholds become independent from signal duration. The critical durations are frequency‐dependent following the general function:tc=p⋅fq(withq<0). This frequency‐dependent nonlinearity could alos be extracted from available data on human hearing. The present results and respective data of the human ear are discussed with reference to a critical‐band‐related summation theory assuming fixed critical bands even for very short signal durations.Subject Classification: [43]65.68, [43]65.75, [43]65.35; [43]80.50.

ISSN:0001-4966    

DOI:10.1121/1.381030

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Observers performed a monaural, yes–no detection task under conditions of signal frequency uncertainty. This frequency uncertainty could be reduced by use of a contralateral cue. The major cue types were a single‐tone cue with the same frequency as the potential detection tone and a three‐frequency cue with the potential signal frequency as the intermediate component. Performance obtained with a single‐tone cue rivaled levels obtained when signal frequency was fixed over a block of trials. Performance with a three‐ frequency cue, requiring extraction of relevant frequency information, produced performance levels only slightly lower than the single‐tone cue condition. Two major conclusions were drawn from the data: (1) The observer, utilizing the single‐tone cue, can nearly eliminate the detrimental effects of signal frequency uncertainty. (2) The ’’hearing out’’ process used to extract relevant frequency information from the three‐frequency cue is nearly complete. The relatively strong support for Ohm’s law obtained from this study may be due, in part, to the level of the auditory system tapped by the present task.Subject Classification: [43]65.50, [43]65.75, [43]65.54.

ISSN:0001-4966    

DOI:10.1121/1.381031

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Psychometric functions were obatained for the interaural conditions NoSo and NoSπ in both forward and backward masking using masks of different durations. In addition, data were collected for the Sm, Sπ and So conditions without an external mask. The slope parameterkand the signal level required for 76% correct detection were computed with a least‐squares technique. The results were that both temporal masking and temporal masking‐level differences (MLDs) increased monotonically with longer mask durations. This mask‐duration effect was more pronounced for forward masking than for backward masking. Without an external mask, the signal was about 3 dB more detectable in the So configuration than in the Sπ configuration, and it was about 4 dB more detectabe in the Sπ configuration than in the Sm configuration. The psychometric functions were generally steeper for the NoSπ condition than for the NoSo condition in forward masking, but not in backward masking. They were also steeper for the Sπ condition than for either the Sm or So conditions without an external mask. The temporal properties of a typical detection model consisting of a filter centered at the stimulus frequency followed by a rectifier and a final ’’leaky’’ integrator were found to explain much of existent temporal masking data. Signal:500Hz, 8 msec; interstimulus interval: 5–10 msec; mask: wide‐band noise; method: two‐interval forced choice.Subject Classification: [43]65.62, [43]65.58, [43]65.68.

ISSN:0001-4966    

DOI:10.1121/1.381032

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Synthetic speech sounds were used as input signals to the guinea pig’s auditory nervous system. Single‐unit responses to these signals were recorded from the cochlear nucleus. The results indicate that considerable information concerning acoustic cues of these signals is encoded within the neural responses.Information concerning formant frequency values, formant transitions within the signals, and rate of impulse excitation is present within the firing patterns of individual neurons.Subject Classification: [43]65.48; [43]70.30, [43]65.59, [43]65.42.

ISSN:0001-4966    

DOI:10.1121/1.381033

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

In an effort to determine whether the pitch shift of the residue is strictly proportional to the frequency spacing between the stimulus components, observers were asked to match the pitch of waves with component spacings of 100, 200, 300, or 400 Hz. The stimuli were sets of 6 or 12 equal‐amplitude sinusoids and the position of each set was varied throughout the frequency range in which the resiude was audible. The pitch shift of the residue showed a disproportionate increase with component spacing for stimuli containing low‐frequency components. Six‐component waves produced slightly larger pitch shifts than 12‐component waves, again when low‐frequency components were included. As the spectral location of the set increased, both effects decreased; once the lowest component in the stimulus was more than about five times the component spacing, both effects were minimal. The results indicate that the dominance region is a function of the absolute, as well as the relative, frequency of the components in this case.Subject Classification: [43]65.54, [43]65.35, [43]65.75.

ISSN:0001-4966    

DOI:10.1121/1.381034

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

A forward‐masking situation was investigated where more energy added to the masker decreased the threshold of the signal. The signal was a single sinusoid. The masker contained two frequency components: one at the same frequency as the signal, and one at a variable frequency. For certain frequencies and intensities of this variable masker component the threshold of the signal was lower than if that component were not present.This decrease in threshold is unmasking. Unmasking is interpreted as being caused by the suppression of the fixed masker component by the variable masker component, thus producing less masking at the signal frequency. The basic pattern of masking and ummasking was qualitatively similar to the pattern of pulsation thresholds observed by Houtgast [Acustica 29, 168‐179 (1973). Unmasking was not observed at absolute threshold or in a simultaneous masking situation. Unmasking was observed at all signal frequencies tested (0.5–6.0 kHz) and was not dependent on the phase of the masker components or the phase between the masker and the signal. When the frequency of the variable masker component was less than the signal frequency, unmasking was dependent on only the intensity of the variable component. However, when the variable frequency was greater than the signal frequency, unmasking was dependent on the difference in intensity between the two masker components. The existence of unmasking in a forward‐masking situation does not depend on whether or not the masker and signal are turned on and off abruptly or smoothly. These characteristics of unmasking are not in conflict with the assumption that this effect is caused by the variable masker component suppressing the other masker component.Subject Classification: [43]65.58, [43]65.68, [43]65.50.

ISSN:0001-4966    

DOI:10.1121/1.381007

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

The frequency limits within which dichotic pitch fusion occurs have been measured as a function of the frequency. The relative frequency differences for the centers of the fusion frequency bands for pure tones coincide with those for binaural diplacusis at corresponding frequencies. A complex (residue) sound fuses only if the fusing conditions for all its individual spectral components are fulfilled. Dichotic fusion of repetition pitch (produced by mixing noise with the same noise, delayed) occurs only if the same noise source is used to produce the signals that are presented to the two ears. Some additional data are presented from experiments with dichotic stimulation with tones of different intensities, where a monotic pitch shift towards the loudest signal is found.Subject Classification: [43]65.54, [43]65.62.

ISSN:0001-4966    

DOI:10.1121/1.380989

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP

摘要:

Three groups of four preschool children who were profoundly deaf or had severe hearing impairment were given training to produce constant–vowel (CV) syllables. One group palpated a vibrotactile vocoder‐type display of the acoustic signals. One group used an analogous visual display. Children in the third (control) group were given reinforcement in the form of slide or puppet displays. In theinitialsessions, all three groups of children were trained to vocalize in response to a ’’light out’’ signal. No displays were used. The children were then trained to pay attention to the displays and to model CV syllable series presented by the experimenter. In thefinalsessions all three groups of children were given a model CV syllable series and encouraged to respond by vocalizing when given the microphone and a ’’light out’’ signal. At the same time they had to attend to the tactile, visual, or nonspeech display. The ratio of CV syllables to all syllables, (CV+V), was calculated for each child for the initial and for the final sessions, and the difference score obtained. The paired observationt‐test indicated a significant increase in the ratio for the experimental groups and no significant change for the control group. We conclude that the acoustically driven nonauditory displays were an essential factor in the observed change in CV production.Subject Classification: [43]70.75; [43]65.82, [43]65.64, [43]65.70.

ISSN:0001-4966    

DOI:10.1121/1.380990

出版商:Acoustical Society of America    

年代:1976

数据来源: AIP