摘要:

Subjects used a computer‐controlled sorting apparatus to initiate the presentation of 16 different consonant sounds, each followed by the vowel /a/. Each subject arranged 16 pegs, which assessed the auditory stimuli, on a 16×16‐hole board so that the distances between pairs of pegs reflected the similarities of the corresponding consonant sounds, i.e., the closer the pegs, the more similar the sounds. It was assumed that each subject's arrangement would include both information about the relative importance of attributes of the stimuli and noise, owing to incomplete checking of all 120 interstimulus distances. Euclidean distances in the subjects' arrangements served as input to the Carroll‐ChangINDSCALprogram [Psychometrika (1970) (to be published)]. The resulting group stimulus space revealed a separation between continuants and stops. Nasals were clustered. Pairs of stops differing only in voicing were grouped together.

ISSN:0001-4966    

DOI:10.1121/1.1976061

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Spoken connected discourse was interrupted for testing immediate recall at points where the speech just presented contained an identical sequence of words in one of two syntactic configurations. The clause unit previous to the one interrupted belonged in one condition to the immediate sentence, while in the other condition it was part of the previous sentence (e.g., “Before Donahue could finish, the members charged. Gaining access to the speaker's platform, they knocked down the local president twice.” vs. “Donahue was helpless to prevent members from gaining access to the speaker's platform. They knocked down the local president twice.”). Subjects were asked to listen normally to the speech and to write down as much as they could remember from just before the test pauses, or they were given the first word from the identical sequences as prompts (“gaining” in the example), and instructed to write down the speech from there up until the pauses. Results obtained from various verbatim measures of free and prompted recall support only the immediately heard clause and the immediate sentence as retrievable units in memory.

ISSN:0001-4966    

DOI:10.1121/1.1976077

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

A theoretical method of determining the suitability of a material for use in elastic surface wave applications as well as the most suitable crystallographic directions for such uses will be described using the elastic, piezoelectric, and dielectric matrices of the crystal class to which the material belongs. The behavior of the more frequently used materials such asSiO3,LiNbO3, and Cds will be discussed. Directions of energy flow for different orientations in these materials will be derived.

ISSN:0001-4966    

DOI:10.1121/1.1976088

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Frequently, the transmission loss of panels must be estimated from limited data for use in design problems. Usually, the panels involve complex constructions where the assumptions of single‐panel theory cannot be reasonably applied. A simplified analysis of the dynamics of some complex panels is presented which leads to a straight‐forward prediction scheme based on modifications of the forced wave transmission loss of a single homogeneous panel. Details of the analysis and comparisons with experiment are provided for the homogeneous panel, two‐ and three‐layer panels, orthortropic panels, and ribbed panels.

ISSN:0001-4966    

DOI:10.1121/1.1976100

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

For a monopole source, the interior reverberant mean‐squared pressure is within ±1 dB of the asymptotic value if the source distance is greater than 0.5λ from a wall. For a spherical random dipole source, such as the Ilg reference sound source (RSS) used in the substitution technique of measuring sound power, this distance increases to about 1.0λ. Since most reverberant room dimensions are of the order of 2λ in the lowest13‐octband of interest, some care must be exercised in low‐frequency measurements. The mean‐squared pressure was experimentally measured as a function of the location of the RSS in a 300‐m3a reverberant room. The results suggest that the first reflection from the walls dominates the pattern It is experimentally shown that stationary nearfield diffusers placed at the walls can be used to decrease the variance of the sound power output arising from the location of the RSS. The use of tilted walls in the design of a reverberant room should have the same effect.

ISSN:0001-4966    

DOI:10.1121/1.1976110

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The techniques of linear programming have been applied to the synthesis of optimum directional patterns from arrays of point elements. A practical linear model of the problem can be formulated by dealing with the real and imaginary components of the directivity function. The size and geometry of arrays that can be treated by this approach are limited only by computation time and computer storage requirements. Numerical examples are given for arrays of up to 70 elements.

ISSN:0001-4966    

DOI:10.1121/1.1976120

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Two groups of four monaural chinchillas were exposed for 2 h to a 700–3000 Hz noise at 117 dB SPL. In one group the exposure was continuous; in the other, eight 15‐min exposures were separated by 45 min of quiet. Both exposures produced initial CTSs so large as to be essentially unmeasurable. However, by 150‐min post‐exposure, the CTS had to be dropped to about 70 dB for the intermittent group, but was still 100 dB for the continuous group. Finally, although the intermittent group showed full audiometric recovery two weeks after exposure, the continuous group had 40 dB of PTS after three months. Clearly, damage‐risk criteria that ignore the temporal pattern of the noise exposure (such as the present proposal before the International Standards Organization) are grossly incorrect, just as one would infer from TTS‐alone studies on humans and from the relatively low actual incidence of hearing losses among workers in which exposures to high levels are intermittent, such as in miners, foresters, and rock musicians. [Supported by the National Institutes of Health, Public Health Service, and Department of Health, Education, and Welfare.]

ISSN:0001-4966    

DOI:10.1121/1.1976136

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The effects of transection of the tapezoid body upon the cat's ability to localize sound were investigated. Four cats were trained to localize pulses of broad‐band noise in a free‐field situation, and their thresholds for minimal detectable angle were determined. After transection of the trapezoid body, each animal was tested for retention of the localization habit. Two animals retained the localization habit and showed little or no loss in threshold for localization; the other two failed to retain the habit and were unable to relearn to localize. Other auditory tests on the latter two animals indicated that they could learn to respond to a sound signal and that they could learn to discriminate between tonal patterns (high‐low‐high versus low‐high‐low). Electrophysiological records, obtained from each cat after testing was completed, showed that evoked potentials could be obtained from auditory areas of the cerebral cortex when click stimuli were presented to the ear. A comparison of the anatomical evidence for animals that retained the localization habit and those that were unable to relearn suggests that the anterodorsal portion of the trapezoid body may be crucial for localization. [This research was supported by the National Science Foundation.]

ISSN:0001-4966    

DOI:10.1121/1.1976146

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Adults of three species of the 17‐yr cicada,Magicicada septendecim, M. cassini, andM. septendecula, emerge from the ground together over a three‐week period to mate and lay eggs. The males produce sounds (bursts of 1.0–1.5 kHz forseptendecimand 4.0–6.0 kHz forcassiniandseptendecula) when congregating and when disturbed. Neural responses from within the chitinous capsule of the auditory receptors showed greatest sensitivity between 1.0 and 3.0 kHz in male and femaleseptendedimand between 3.5 and 7.0 kHz in both sexes ofcassiniandseptendecula. The tympanic membrances of the males are partially collapsed by muscles which contract during sound emission, reducing auditory sensitivity by 5–15 dB. Behavioral audiograms of males indicate best hearing inseptendecimat 1.2–1.8 kHz and 4.5–6.0 kHz incassini. Each species is very insensitive to frequencies used by the other. The sound level (80–95 dB SPL) around infested trees probably discouraged predation by driving away birds.

ISSN:0001-4966    

DOI:10.1121/1.1976148

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The use of distinctive features as cues to speech recognition should result in performances for signals that differ as a function of response alternatives. Recognition of a speech unit that shares many features of alternative responses must rely upon reception of the one or few uniquely held features. Recognition of a speech unit that shares few, if any, features will occur with reception of (almost) any of its features. A four‐person talker‐listener round robin generated nonsense syllables of a CV type using the consonant /t/ and two others, and the vowel /a/ and two others. Each of the nine syllables was delivered 100 times in random order in each set. Each listener responded with a choice for each signal plus a confidence rating on his decision. Additional sets were generated by retaining the consonants and the /a/ but using two different vowels, or by retaining the vowels and /t/ and using two different consonants. Other sets used the original elements but always placed an /r/ for a CrV syllable, and still others added a final /k/ for a CrVk syllable. Utilities of response choices were systematically varied and response confusions generated for each talker‐listener dyad. Results on stability of recognition performance pertinent to the influence of context are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1976158

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP