摘要:

Experiments on the perception of consonants have indicated that the direction of a formant transition may be a cue to the perception of either place of articulation or manner of articulation, and that directions of second‐ and third‐formant transitions are related to place of articulation (labial, dental, velar, etc.), whereas the direction of first‐formant transitions is related to manner of articulation (plosive, fricative, nasal, etc.). A study of the five plosive and fricative phrayngeals of Arabic suggests that the direction of first‐formant transitions may act as a cue for the perception of consonantalplaceof articulation.

ISSN:0001-4966    

DOI:10.1121/1.1972532

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

An earlier paper [J. Acoust. Soc. Amer.41, 161 (A) (1967)] gave a simple expression for predicting the transmission loss in shallow water under conditions of downward refraction when incomplete environmental knowledge precludes the use of elaborate theory. The present paper considers the case of near‐isovelocity water with parallel lossy boundaries. Summing modes on a computer intensity‐wise, assuming random phase between modes, yields a set of prediction curves for the loss in terms of normalized ranger/Hand normalized water depthH/λ with boundary reflection loss, expressed in decibels per degree grazing angle, as a parameter. The random phase assumption is justifiable, as a practical matter, by the effects of natural environmental irregularities, by the smallness of mode interference effects when many modes are trapped and by the interest of the engineer in only the average sound field at a distance. Summing discrete modes and images in this way, as well as integrating a continuous distribution of modes and images, leads to identical values of loss whenH/λ is large. Comparisons of the prediction curves with field data reported in the literature are made.

ISSN:0001-4966    

DOI:10.1121/1.1972540

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Evoked responses to 118‐dB SPL clicks recorded from the rat's dorsal cochlear nucleus (DCN) have a complex waveform with a first biphasic positive‐negative component that represents auditory‐nerve axon discharge. The second component, which follows the first by 0.8 to 1.3 msec. is a smaller positive‐negative wave and may reflect second‐order fiber discharge within the DCN, but does not representN2. In the extreme lateral DCN, a third evoked response component is a large positive‐negative biphasic wave that may be related toN2. In the rest of the DCN, the third component is a slow monophasic baseline shift lasting 5–6 msec, upon which the second components may frequently be superimposed. As click intensity is varied between 83 and 108 dB SPL, rarefaction‐click DCN responses have shorter latencies and greater amplitude than do condensation‐click responses reflecting at the cochlear nucleus level the earlier excitation of auditory‐nerve dendrites by upward excursions of the basilar membrane. [Supported by NINDB grant and Middlebury College.]

ISSN:0001-4966    

DOI:10.1121/1.1972567

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

When a noiselike auditory stimulus is used to study the auditory nervous system, it is difficult to determine the evoked response dependency upon the transitory changes in stimulus intensity and upon its spectrum. This is particularly true when the noise intensity fluctuates, as in filtered white noise, for example. However, if a relatively long tone burst is briefly frequency modulated (FM) by noise, the tone‐noise and noise‐tone transitions occur with no SPL intensity fluctuation. The responses can then be ascribed solely to the spectral transitions. A series of experiments has been performed on awake cats subjected to such stimuli in which the noise bandwidth was varied. Responses to the tone‐noise transitions were obtained from epidural electrodes and were compared with responses to both pure‐tone bursts and FM bursts with the same envelope. Of considerable interest is the finding that for relatively large bandwidths, the response is greater to the tone‐noise transition than to onset of an FM noise burst with the same bandwidth. [Supported by the National Institutes of Health, U. S. Department of Health, Education, and Welfare.]

ISSN:0001-4966    

DOI:10.1121/1.1972654

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The cues for discriminating fricatives are known to lie both in the spectrum of the friction itself and in the formant transitions into adjacent vowels. Although both these cues can vary acoustically with context, only the formant‐transition cue is lateralized in dichotic listening. Steady‐state fricatives, whether isolated or followed abruptly by a vowel were recalled equally well from either ear; however, when the appropriate transition was added there was an improvement in recall from the right ear, but no improvement from the left. This advantage for the right ear remained when the friction was removed but the transition left intact to give a stoplike sound. The right‐ear advantage for recall of dichotically presented initial stops has been confirmed and a similar advantage found for both released and unreleased final stops. This latter effect is influenced by the relative onset times of the preceding vowels within a dichotic pair. By contrast, no preference for either ear could be found for isolated vowels of the same duration as the stop transitions (40 msec). These results indicate that speech sounds only give an advantage for the right ear in a dichotic listening task when they contain formant transitions.

ISSN:0001-4966    

DOI:10.1121/1.1972683

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The perception of the vowel pair /ɑ‐æ/ was studied both in isolation and in the context /d‐dɔl/ (bottle‐battle). A set of eight stimuli were created on a speech synthesizer by varying second formant center frequency in equal logarithmic steps, such that Stimulus 1 sounded like / ɑ / or /bɑdɔl/ and Stimulus 8 sounded like /æ/ or /bædɔl/. The method of absolute identification was used to analyze the psychological distance between adjacent stimuli in terms of d′. It was found that the phoneme boundary effect was observed for the vowel pair in word context only; subjects could differentiate between stimuli in the center of the continuum (stimulus Pairs 4 and 5) much easier than between stimuli at the ends of the continuum (Pairs 1 and 2 or 7 and 8). Isolated vowel stimulus pairs (approximately 250 msec in duration) were differentiated equally well over the whole continuum. [This work was supported in part by the National Institutes of Health.]

ISSN:0001-4966    

DOI:10.1121/1.1972690

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Twelve isolated sustained English vowels were magnetically recorded and then presented to English speaking subjects in pairs. The subjects were asked to estimate the perceptual similarity of each pair by drawing a horizontal line. The length of the line corresponded to the degree of similarity. A short line represented a more similar pair; a long line, a less similar pair. The average length of all lines for all auditors was computed for each pair of vowels. These average values were summarized in a matrix and were used in subsequent analysis. Two statistical models were used in the analysis: Multidimensional Scaling (MDS: Shepard, Kruskal) and Hierarchical Clustering Schemes (HCS: Johnson). These models bring out the most prominent dimensions in the set of similarity values and are interpretable generally as phonetic features. Feature strength and feature markedness were also computed. [This work was supported by The National Institutes of Health, U. S. Department of Health, Education, and Welfare.]

ISSN:0001-4966    

DOI:10.1121/1.1972698

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The exterior Dirichlet problem can be formulated in terms of either a first‐kind or a second‐kind integral equation for the normal velocity at the surface of the scatterer. However, neither of the standard equations has a unique solution at all frequencies. It is shown here that a third formulation, obtained simply by forming a linear combination of the two original equations, does give the correct solution uniquely at all frequencies. Similarly, the exterior Neumann problem can be described by a first‐ or second‐kind equation for the pressure at the surface, neither of which has a unique solution at all frequencies; but a linear combination of the two equations again yields the correct solution uniquely. Numerical results for the analogous problem in electromagnetics indicate that the new formulations should be well suited for practical computation.

ISSN:0001-4966    

DOI:10.1121/1.1972708

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The electrical driving‐point admittance of a linear transducer is linearly dependent on a sufficiently small impedance loading its mechanical port (a sufficiently small load impedance is one that is much smaller than the transducer's mechanical driving‐point impedance). This makes possible a method for measuring the mechanical impedance presented by a smooth surface to a sliding indenter. The indenter acts as the mechanical port of a transducer whose electrical admittance causes the output voltage of a linear active network to equal the surface impedance in amplitude and phase. Calibration of the system does not depend on a detailed knowledge of the transducer's dynamics, but does require that the transducer be operated at frequencies for which its mechanical impedance is much larger than the surface impedance. This method has been used to measure groove impedances of phonograph records.

ISSN:0001-4966    

DOI:10.1121/1.1972729

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The sound energy density maintained in a room at the (nearly) discrete frequency ω produced by a musical instrument is proportional to the quantityA(ω)=D(ω)⋅δω⋅T〈∫ψ̇φdS〉av. HereD(ω) is the frequency density of room modes, the φ's are pressure wavefunctions belonging to the room,Tis the mean reverberation time for these modes, and ψ is the surface displacement of the second source. Integration is over the source surface, and the averaging is over room modes within the bandwidth δω. The latter depends on (1/T) via the Schroeder frequency, and on the “natural linewidth” of the source spectrum:Ais dependent on the linear sizeLof the source via some fraction of (ωL/c). Room selection and microphone and player location for meaningful spectrum measurement may be guided by general properties ofA, φ, andD. A violin recording and transposition to synthesize the sounds of the Hutchins family of new violins will be demonstrated as an application of these principles. Calibration procedures will also be described.

ISSN:0001-4966    

DOI:10.1121/1.2040968

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP