摘要:

The general observation that dual sensory input enhances signal detectability is of considerable interest from the information‐processing standpoint. Previous experiments on the effects of intersensory interaction have been concerned primarily with an observer's performance on a vigilance task. These studies have not produced results that are sufficiently precise to define the extent and manner of sensory interaction. This study is concerned with obtaining precise measurements of interaction occurring between auditory and visual sensory‐information‐processing networks. Separate auditory and visual threshold functions are determined and analyzed in terms of signal‐detection theory. A bisensory threshold function is also determined, using equated stimuli levels derived from the individual sensory functions. The results of the bisensory test are compared to a theoretically derived curve based on the hypothesis of probabilistic adding and are found to have good correspondence.

ISSN:0001-4966    

DOI:10.1121/1.1910318

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

In order to account for binaural improvements in detection on the basis of interaural phase shifts, or time deviations, it is necessary to assume that the “critical band” is a sinusoidlike process and that corresponding processes from the two ears interact. Support for this assumption is reported for the binaural conditions N0Sπ, NπS0, N0S0, N0Sm, and NπSm. It was found that neither interaural level nor bandwidth differences matter so long as the levels within the critical bands at the two ears are unaffected. Detection at one ear is affected only by a narrow band of frequencies at the opposite ear, thus confirming the assumption of a band‐limited binaural interaction. Experiments were carried out with three different maskers: a narrow‐band noise, a medium‐band noise, and a medium‐band noise with a gap in it. The narrow‐band masker was as effective as the medium‐band masker. The noise with a gap in it, however, produced a minimal release from masking when added at the nonsignal ear. These findings are discussed within the context of those of earlier investigations.

ISSN:0001-4966    

DOI:10.1121/1.1910333

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

A basic difference is shown to exist between the hearing of man and that of the goldfish. The goldfish possesses a direct relationship between the sound energy (percent of time that the tone is on) and its threshold, which is lowest with continuous tones. In humans, however, the threshold is dependent upon the duration of each tone pulse. With long‐tone pulses, the human threshold is lower than with continuous tones. It is hypothesized that this difference is due to a lack of adaptation in the goldfish auditory nerves, whereas the human has increased nervous activity at the beginning and end of each tone pulse. Thus, the level of sensation in the human appears to depend on the amount of nervous activity produced in the receptor by a stimulus pulse. These findings show that the fish are relatively better adapted to hearing the kinds of sounds found in their natural environment than is the human observer. Some ideas are presented as to how the determination of tone‐pulse thresholds could aid in certain clinical investigations.

ISSN:0001-4966    

DOI:10.1121/1.1910309

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Two models describing binaural‐masked thresholds (the delay‐line model and the EC model) are checked by extended experiments. They prove only a limited validity. Therefore, a new model, the accumulation model, is proposed, one that does not use any delay at all and that is, therefore, able to process interaural differences on a more general basis. It is in full agreement with former calculation schemes for monaural‐masked thresholds. This model explains all effects in binaural masked thresholds known so far. Binaural‐masked thresholds computed according to this model are in good agreement with experimental data.

ISSN:0001-4966    

DOI:10.1121/1.1910320

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The total sound absorption due to a rank of organ pipes arises chiefly from internal resonance losses and also from energy dissipation taking place at the external surfaces of the pipes. The first contribution has been discussed elsewhere [A. H. Benade, J. Acoust. Soc. Am.38, 780–789 (1965)], and the second is reported here. Scattering of a plane wave incident obliquely on a long circular cylinder is calculated, and the results are used to find the energy absorbed via viscosity and also via the short‐circuiting of the wave's temperature fluctuations produced by an isothermal boundary. It is shown that an absorption coefficient can be defined for the pipe surface that is approximately independent of the radius/wavelength ratio. The corresponding coefficient for viscous and thermal losses at a plane surface is also calculated. The result areᾱcyl = 2.3⋅10−5(ω)12andᾱPLANE = 6.8⋅10−5(ω)12. The latter result agrees with a calculation by Walther [J. Acoust. Soc. Am.33, 127–136 (1961)]. Computation of the absorption by a rank of pipes is simplified by using the scaling principles followed by organ builders. It is shown that the external absorption is negligible below 500 Hz, and is only about 0.06 m2at 2000 Hz for a 73‐pipe rank centered at middle C.

ISSN:0001-4966    

DOI:10.1121/1.1910326

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Clarinet, oboe, bassoon, tuba, flute, trumpet, trombone, French horn, and English horn tones have been synthesized with partials controlled by one spectral envelope (fixed for each instrument regardless of note frequency) and three temporal envelopes. Musically literate auditors identified natural tones with 85% accuracy and our synthesized tones with 66% accuracy; a number of the confusions were intrafamily. With intrafamily confusions tolerated in the scoring, the auditors identified natural tones with 94% accuracy and our synthetic ones with 77% accuracy.

ISSN:0001-4966    

DOI:10.1121/1.1910327

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The results of binaural audiometric tests of 83 profoundly deaf children were compared with their scores on a standardized speech test (the Phoneme Count), the American Medical Association (1947) audiogram‐average assessment of percentage hearing loss for speech, and a qualitative diagnosis of speech defect. A contingency table of responses at 10‐dB intervals against seven frequencies in both ears was compiled, and nonparametric analyses were undertaken to ascertain “speech frequencies” for this population. Mean standardized speech test scores per intensity interval appeared, by inspection, to be associated positively with residual hearing at all frequencies from 125 to 8000 cps in both ears, but a formal chi‐square test of the association of speech scores and a response/no‐response measure of each frequency from 125 to 8000 cps established significant relationships 4000 and 250 cps for the worse ear and at 2000, 250, 125, 1000, and 4000 cps for the better ear. The importance of lower frequencies as useful indicators of potential speech development in the profoundly deaf was noted, and the possibility of predicting eventual speech performance from the pure‐tone audiogram was suggested. A lowering of frequency limits and a raising of the level of decibels above normal threshold was advocated for any audiogram‐average method that sought to summarize hearing loss for speech for the profoundly deaf.

ISSN:0001-4966    

DOI:10.1121/1.1910328

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Fairbanks' speech time‐adjusting device has been simulated, using a hybrid computer. This device discards or repeats recorded speech segments to compress or expand the time dimension. A dichotic method for time compression of speech was investigated in which odd‐numbered time segments were presented to one ear and even‐numbered segments to the other ear. A preference test suggested that speech compressed with the dichotic method may be more intelligible than speech compressed with Fairbanks' method. Potential applications for time‐adjusted speech and possibilities for further research are suggested.

ISSN:0001-4966    

DOI:10.1121/1.1910329

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

A phonemic‐confusion matrix for speech in a helium atmosphere was constructed for use in predicting intelligibilities of specially constructed vocabularies for such environments. There is a marked similarity between helium speech and speech in air when intelligibility according to linguistic classification is observed. However, unaccountable differences do exist between the two breathing media for ranked intelligibilities of specific consonants.

ISSN:0001-4966    

DOI:10.1121/1.1910330

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Some qualitative data on the nature of the speech distortion caused by respiration of a helium‐oxygen atmosphere are presented. Previous corrective‐processing techniques are discussed, and an advanced technique that overcomes their disadvantages described. The experimental system is based upon time‐domain speech‐processing methods and is capable of retaining the natural pitch rate of the speaker's voice while correcting the formant shifts caused by the helium‐rich atmosphere. This system uses digital‐processing methods and is capable of operating on continuous speech in on‐line applications. It promises a practical solution to the problem of providing normal voice communication in a helium environment.

ISSN:0001-4966    

DOI:10.1121/1.1910331

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP