摘要:

The normal procedure in acoustical designs usually emphasizes audience acceptance. This approach often results in unfavorable acoustical conditions for performing artists, both instrumental and vocal. The imbalance occurs form neglect of the musicians’ need for mutual communication, and too great an emphasis on achieving ’’optimum’’ reverberation conditions. There have been notable examples of halls meeting accepted reverberation criteria which have nevertheless proved to be unsatisfactory, and many of these gave trouble because of performance difficulties as transmitted to the audience. Conversely, reverberation conditions can differ considerably from the norm, and still provide a satisfactory hall if the stage is properly designed. Study of a variety of halls strongly suggest that an essential requirement for music is that conditions should be suitable for performers. Architectural designs that provide ample sound reflecting and diffusing structures on stage to enable artists to hear each other well, blend the sound, and achieve favorable ’’local reverberation’’ are usually judged to be excellent by both performers and audience. This essential result can be achieved even in rooms which depart appreciably from standard reverberation time criteria.

ISSN:0001-4966    

DOI:10.1121/1.382279

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

The cross‐sensor field of an array consists of all products of the narrow‐band quadrature signal measured at one sensor multiplied by the complex conjugate of the quadrature signal measured at a second sensor. Three algorithms which use the cross‐sensor field to determine the level and direction of a set of acoustic waves incident on a billboard array are compared. These are correlation (conventional) beamforming, maximum likelihood estimation, and iterative decomposition.

ISSN:0001-4966    

DOI:10.1121/1.382256

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

An analysis is presented of the signal gain and the noise gain of a broadside vertical line array operating in a shallow‐water channel with one lossy boundary. The signal gain is derived by representing the signal field as a sum of normal modes, and is shown to lie betweenNand 2Nprovided the number of modes in the field is less than (h/2L); and a simple criterion is derived for the maximum useful aperture of the array, beyond which no significant improvement in signal gain can be achieved. The derivation of the noise gain is based on the assumption that, over the aperture of the array, the noise field can be represented as a linear superposition of plane waves. On introducing the high‐Napproximation it is shown that, for arbitrary anisotropy, the noise gain is the reciprocal of a series of Bernoulli polynomials, the coefficient of each being determined by the directional density function of the noise. A discussion of the noise gain in isotropic noise and in three different anisotropic noise fields illustrates the utility of the approximate method for determining the noise gain.

ISSN:0001-4966    

DOI:10.1121/1.382257

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Several experimental methods of depressing the response of auditory‐nerve fibers to tonal stimuli have been shown to reduce the response to signal frequencies at or near fiber CF (characteristic frequency) more than to frequencies greater or less than CF. In this study we have used a short adapting tone presented before each test‐tone burst to reduce the fiber’s response to the test tone. We observed the effects of changing test frequency when the adapting frequency was held constant at fiber CF. The depression in discharge rate was found to be approximately constant across test frequency.

ISSN:0001-4966    

DOI:10.1121/1.382259

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Results are reviewed concerning some effects, at a units’s characteristic frequency, of a short‐term conditioning stimulus on the responses to perstimulatory and poststimulatory test tones. A phenomenological equation is developed from the poststimulatory results and shown to be consistent with the perstimulatory results. According to the results and equation, the response to a test tone equals the unconditioned or unadapted response minus the decrement produced by adaptation to the conditioning tone. Furthermore, the decrement is proportional to the driven response to the conditioning tone and does not depend on sound intensityperse. The equation has a simple interpretation in terms of two processes in cascade—a static saturating nonlinearity followed by additive adaptation. Results are presented to show that this functional model is sufficient to account for the ’’physiological masking’’ produced by wide‐band backgrounds. According to this interpretation, a sufficiently intense background produces saturation. Consequently, a superimposed test tone causes no change in response. In addition, when the onset of the background precedes the onset of the test tone, the total firing rate is reduced by adaptation. Evidence is reviewed concerning the possible correspondence between the variables in the model and intracellular events in the auditory periphery.

ISSN:0001-4966    

DOI:10.1121/1.382260

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

This investigation was undertaken to enlarge current understanding of the acoustic properties which influence the perception of maleness and femaleness in the voices of prepubertal children. Perceptual judgments of sexual identity were obtained in response to tape recordings of whispered and normally phonated vowels, normally spoken sentences, and sentences spoken in a monotonous fashion. Seventy‐three children provided recordings. The four utterance types were chosen to experimentally manipulate selected physical properties of speech thought to exert an influence on listener judgments of sexual identity. The results of this work suggest that cues stemming from differences in vocal tract dimensions and/or articulatory behaviors provided the primary cues about the sexual identity of these preadolescent children. Although laryngeal source cues could have provided relevant information about the sex of a few children, this variable was felt to play a relatively minor role in the sex recognition process. New information was uncovered about the role certain suprasegmental factors play in the identification of child sex.

ISSN:0001-4966    

DOI:10.1121/1.382234

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Differences in discriminability of stimuli near phoneme boundaries and findings from selective adaptation have been used to argue for the existence of neurophysiological mechanisms—feature detectors—which mediate the perception of speech and speechlike sounds. A detection theory model was used in order to discover whether or not the phoneme boundary effect and the shift in phoneme boundary after adaptation might rather be attributable to changes in response bias. This model was applied in the analysis of phoneme identifications of three sets of stimuli (/áp‐‐áb‐/, /b‐d/, /b‐p/) before and after adaptation. While the origins for the phoneme boundary effect appear to lie below the level of response bias, findings suggest that identification changes after adaptation may be due solely to shifts in criterion, rather than changes at the sensory level.

ISSN:0001-4966    

DOI:10.1121/1.382235

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Imitations of ten synthesized vowels were recorded from 33 speakers including men, women, and children. The first three formant frequencies of the imitations were estimated from spectrograms and considered with respect to developmental patterns in vowel formant structure, uniform scale factors for vowel normalization, and formant variability. Strong linear effects were observed in the group data for imitations of most of the English vowels studied, and straight lines passing through the origin provided a satisfactory fit to linearF1−F2plots of the English vowel data. Logarithmic transformations of the formant frequencies helped substantially to equalize the dispersion of the group data for different vowels, but formant scale factors were observed to vary somewhat with both formant number and vowel identity. Variability of formant frequency was least forF1(s.d. of 60 Hz or less for English vowels of adult males) and about equal forF2andF3(s.d. of 100 Hz or less for English vowels of adult males).

ISSN:0001-4966    

DOI:10.1121/1.382237

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

A version of Griffiths’s Diagnostic Articulation Test (DAT) using three‐word items is described. The test is applicable where monosyllabic words or sentence lists are undesirable or inappropriate. Each word of an item is drawn from a separate set of five monosyllabic real words differing only in the initial or final element. For each item, subjects underline one word in each of the three sets of words for that item on the answer sheet. The test examines reception of 150 words in 7 min as compared with 50 words in 5 min by the usual single‐word format and preserves, moreover, the effects of gross temporal distortions and masking that occur within and between words in consecutive discourse. Discrimination scores for the tri‐word test of intelligibility (TTI) as compared with the Modified Rhyme Test (MRT) and the C. I. D. sentence lists all taped with the same talker were lower when tested in quiet and even relatively lower in noise. The multiple‐choice closed‐set response permits easy administration, scoring, and analysis of confusions; enunciation of three semantically unrelated words in coarticulatory succession preserves interword transitions while limiting the effects of memory and linguistic redundance. The use of the DAT lists permits a somewhat more detailed analysis of errors than use of the three‐word formant with the MRT as proposed by Williamsetal. (Aviat. Space and Environm. Med. 47, 154–158 (1976). The NSMRL TTI is proposed as a relatively ease of administration and scoring are desirable.

ISSN:0001-4966    

DOI:10.1121/1.382238

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP

摘要:

Unlike most frequency domain methods for pitch extraction, here the pitch is computed from a few selected high quality peaks in the spectrum, achieving greater reliability. A new approximate greatest common devisor (AGCD) algorithm is proposed to compute the fundamental frequency of a given set of corrupted harmonics. Authentic harmonic peaks ar4e obtained by logical filtering of the spectrum and the computed fundamental frequency is subjected to an error test using the best of the harmonic peaks. Thus the algorithm provides a voiced–unvoiced decision, as well as the pitch for voiced regions. The results are uniformly good for male and female voices, and error rates are comparable to those for the best algorithms reported in the literature.

ISSN:0001-4966    

DOI:10.1121/1.382239

出版商:Acoustical Society of America    

年代:1979

数据来源: AIP