摘要:

This paper presents a new analytical technique for computing sonar performance which can be run on a programmable hand calculator. It is simple and rigorous, and does not require complex computer simulations which obscure the critical parameters. It allows the individual terms in the sonar equation to have two or more different relaxation times, and allows the Recognition differential (RD) term to be presented as a curve of probability of detection versus signal‐to‐noise ratio (SNR) rather than a jump in probability of detection versus SNR from 0 to 1. This method treats the sonar equation as a random process with a mean and standard deviation as in standard simplified techniques, but treats successive observations of received signals as a multivariate Gaussian distribution with observations correlated in accordance with the decorrelation times of the individual terms in the sonar equation. Restrictions of this method are twofold: the terms of the sonar equation are normally distributed (in dB) and the RD term is derived from a probability of detection versus SNR relationship which is represented by a straight line on normal probability paper.

ISSN:0001-4966    

DOI:10.1121/1.389573

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

An analytical model for the detection performance of multiple channel time history display formats such as used with multibeam systems and spectrograms is presented. The resulting receiver operating characteristic (ROC) curves are presented as a function of the number of lines displayed. A typical comparison with the simple threshold excess decision rule operating on the same data is also presented.

ISSN:0001-4966    

DOI:10.1121/1.389574

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

In this paper we describe magnitude and phase measurements obtained from primary single unit recordings in the cat auditory nerve. Levels range from threshold to 100 dB SPL, with frequencies from 0.1–30.0 kHz. The upper limit on the phase measurements was limited by the loss of neural phase locking at 4–5 kHz. For each unit, the frequency tuning curve (FTC) was measured by the method of Kiang and Moxon [M. C. Liberman, J. Acoust. Soc. Am.63, 442–445 (1978)] to establish the threshold frequency response of the unit. Data from several selected animals, organized by characteristic frequency (CF), are presented showing phase response, group delay, frequency tuning, and tuning slope for each CF range. The major emphasis in this paper is on the ‘‘linear’’ aspects of the data as characterized by the filter properties of the single unit response, however a number of nonlinear (level‐dependent) effects are described. Data are presented showing the phase response normalized by the chochlear microphonic (CM) recorded at the round window membrane. This normalization simplifies the phase data since it produces a constant phase slope with respect to frequency (constant group delay) for high CF units ( fCF>1 kHz) for frequencies more than one octave below their characteristic frequencies. A model of CM, as measured at the round window (RW), is presented and compared to experimental CM measurements. The CM model gives a reasonable fit to the experimental data above 500 Hz. Our interpretation of the CM normalization is that it removes driver and middle ear effects. In the model we assume that the CM is generated by the displacement of the basilar membrane near the round window recording site.

ISSN:0001-4966    

DOI:10.1121/1.389575

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The phenomenon of two‐tone suppression was studied quantitatively in the peripheral auditory system of the green treefrog (Hylacinerea). Linear relationships were found between best excitatory and best suppressor frequency, between response thresholds at these frequencies, betweenQ10dB‐values of excitatory and suppressor tuning curves and best excitatory frequency, and between bothQ10dB‐ values.

ISSN:0001-4966    

DOI:10.1121/1.389576

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Single unit activity was recorded in the auditory nerves of chinchillas. Period histograms were constructed for responses to tones with frequencies 30–1000 Hz. For low‐frequency tones at near‐threshold levels, peak period histogram phases for low‐ and medium‐best‐frequency (BF) neurons (≤3 kHz) ranged from synchronous with condensation at the eardrum to 90° leading it. At near‐threshold (but high absolute) levels, high‐BF (≥8 kHz) neurons responded in phase with rarefaction. At even higher levels, period histograms for responses of high‐BF neurons tended to become bimodal, with one of the modes lagging rarefaction by 90°. Using cochlear microphonics as an indicator of basilar membrane (BM) displacement, at threshold levels, response phase of low‐ and medium‐BF neurons fall within a range between displacement and velocity of the BM toward scala vestibuli. High‐BF neurons respond, at threshold (but high) intensities, in phase with BM displacement toward scala tympani. The rates of growth of frequency sensitivity in responses of low‐BF (+18 dB/oct) and high‐BF (+12 dB/oct) neurons are consistent with preferred response phases corresponding to BM SV velocity and ST displacement, respectively. At supra‐threshold levels high‐BF neurons may fire preferentially to both scala tympani displacement and scala vestibuli velocity. These results support the notion that, for high‐intensity, low‐frequency stimuli, OHC hyperpolarization can induce excitation of the dendrites innervating IHCs.

ISSN:0001-4966    

DOI:10.1121/1.389577

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Experiments were conducted to assess the contribution of place mechanisms to the effect of rise–fall time on wave V of the human brainstem auditory evoked response (BAER). Noise bursts of 4‐ and 10‐ms duration were presented at various rise–fall times (0, 1, 2, and 5 ms). Subtractive high‐pass masking techniques were used to determine the effect of rise time as a function of derived‐band frequency. In general, increasing rise time prolonged wave V latency but did not affect amplitude. Rise‐time effects did not depend on derived‐band frequency and similar effects were seen in the unmasked conditions. In addition, narrowing the derived band did not alter the observed effects on latency and amplitude. Signal envelope showed no effects on traveling wave velocity. These results suggest that place mechanisms contribute little to changes in the BAER associated with rise–fall time.

ISSN:0001-4966    

DOI:10.1121/1.389578

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Frequency‐discrimination thresholds, for a wide range of stimulus frequencies and stimulus levels, were obtained from three normal‐hearing listeners. Linear regression analyses of the present data, and of data from two previous studies, indicate that an SL−1transformation of stimulus level and a (F)1/2transformation of stimulus frequency yield linear dimensions that allow accurate predictions of frequency‐discrimination thresholds from normal‐hearing listeners over a wide range of stimulus frequencies (125–8000 Hz) and stimulus levels (5–80 dB SL) with a single prediction equation.

ISSN:0001-4966    

DOI:10.1121/1.389579

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

We used a selective adaptation procedure to investigate the possibility that differences in the degree to which stimuli within a phonetic category are considered to be good exemplars of the category—that is, differences in perceived category goodness—have a basis at a prephonetic, auditory level of processing. For three different phonetic contrasts (/b–p/, /d–g/, /b–w/), we assessed the relative magnitude of adaptation along a stimulus continuum produced by a variety of stimuli from the continuum belonging to a given phonetic category. For all three phonetic contrasts, nonmonotonic adaptation functions were obtained: As the adaptor moved away from the category boundary, there was an initial increase in adaptation, followed by a subsequent decrease. On the assumption that selective adaptation taps a prephonetic, auditory level of processing, these findings permit the following conclusions. First, at an auditory level there is a limit on the range of stimuli along a continuum that is treated as relevant to a given contrast; that is, the stimuli along a continuum are effectively grouped into auditory categories. Second, stimuli within an auditory category vary in their effectiveness as category members, providing an internal structure to the categories. Finally, this internal category structure at the auditory level, revealed by the adaptation procedure, may provide a basis for differences in perceived category goodness at the phonetic level.

ISSN:0001-4966    

DOI:10.1121/1.389455

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

To evaluate the relationship between physical characteristics of the lips during vowel production and vowel lipreading confusions, four female talkers were videotaped producing 15 American English vowels and diphthongs in an /h/‐V‐/g/ context. Ten normal‐hearing adults identified the stimuli through lipreading. Three analyses were performed. First, using confusion matrices for individual and pooled talkers, the stimuli were located in a two‐dimensional space using multidimensional scaling. The ten monophthongs revealed a clear lip spreading/rounding dimension and a tongue height dimension, and while diphthongs also showed influence of lip rounding, more variability on the tongue height dimension was apparent. Second, tracings were made of the talkers’ lips on a single videotape field representing the maximum opening or constriction for each of the 40 monophthong tokens (ten vowels×four talkers), and six physical measurements of the tokens were derived as descriptors of the vowel nuclei. Third, difference scores and other measures of physical pairwise similarity were used as predictors of two ways of representing the vowel lipreading confusions in a multiple regression paradigm. Results indicated that the physical measures were moderately successful as predictors of vowel perception (accounting for approximately 50% of the variance in the perceptual distance measure), although considerable differences in the strength of the prediction occurred among talkers.

ISSN:0001-4966    

DOI:10.1121/1.389537

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Recordings of nonsense syllables (VCV construction) were presented to groups of children aged 5, 7, 9, 11, and 13 years and young adults under monaural (reverberation time=0.6 s) and binaural (reverberation times=0, 0.4, and 0.6 s) conditions of reverberation. Phoneme identification performance was affected by age, reverberation, and mode of presentation (monaural versus binaural). The major findings were (1) phoneme identification scores in reverberant conditions improved with increasing age and decreased with increased reverberation time; (2) children’s performance in reverberant conditions did not reach asymptote until age 13; (3) binaural performance was consistently better than monaural performance for all age groups, with 5‐year‐olds showing the largest binaural advantage.

ISSN:0001-4966    

DOI:10.1121/1.389538

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP