摘要:

Cochlear microphonics have been explained in terms of a varying resistance at the hair cells that modulates resting currents and voltages in an electric network powered by biological dc “batteries.” In this paper, the distributed electric circuit of a 2‐mm‐long section of the first turn of the cochlea is approximated by a lumped network consisting only of linear elements, and including both fixed and variable capacitances across membranes as well as the variable resistance. When this circuit is driven by sinusoidal parameter variations, the voltage and current analogous to the cochlear microphonic and its concomitant hair‐cell current exhibit these steady‐state phenomena: (1) frequency‐sensitive gain; (2) frequency‐ and amplitude‐sensitive phase shift; (3) dc shifts of both polarities in response to purely ac stimulation, analogous to the summating potential; (4) waveform distortion. These results show that an additional stage of signal processing may exist between basilar‐membrane vibration and nerve spike trains, and certainly between basilar‐membrane vibration and observed cochlear potentials.

ISSN:0001-4966    

DOI:10.1121/1.1913324

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The just‐noticeable difference (JND) for selected aspects of voice fundamental frequency (F0) contours was determined by varying theF0control parameter of a digitally simulated terminal analog speech synthesizer. Data were obtained from three subjects for a number of 250‐msec segments of the synthetic vowel /ɛ/ differing only in fundamental frequency. Results indicate that the subjects can detect a change of 0.3 Hz in a constantF0contour whenF0= 120 Hz, but the JND is an order of magnitude larger (2.0 Hz) when theF0contour is a linear descending ramp (32 Hz/sec). Sensitivity to rate of change ofF0in linear ramps is surprisingly good; greatest sensitivity occurs when one ramp increases and the other decreases (JND = 12 Hz/sec). High‐pass filtering of the stimuli improves performance slightly, suggesting that the fundamental component is not involved in the detection of changes inF0. Substitution of the synthetic stimulus /ya/ with its dynamic formant contours in place of /ɛ/ degrades performance only very slightly. Implications of these data for models of pitch perception mechanisms are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1913333

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The thresholds for the detection of frequency transition were obtained for the tone bursts in which the frequency was linearly changed from the initial value of 1000 Hz either during almost the whole burst duration or during a portion of it. The onset of transient had various delays from the beginning of the tone burst. The burst durations were 32, 102, 302, and 1000 msec. It was found that the nearly constant thresholds were obtained for a given burst duration as long asW(=T1+13T2)was held constant, whereT1was the duration of the initial segment of steady frequency andT2was the duration of frequency transition. The thresholds were greater when the transition occurred near the burst onset than when it occurred near the cutoff, and in the former case, the thresholds were influenced by a rise time of tone burst. The thresholds were smallest when the frequency transitions occurred in the middle of the tone burst. It is suggested that there are two mechanisms for auditory detection of frequency transition: one is based on the pitch difference and the other on the gliding pitch.

ISSN:0001-4966    

DOI:10.1121/1.1913316

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Relations between bowing parameters, i.e., force applied, bow position, and velocity, are derived in terms of load impedance presented by bridge to string, characteristic impedance, and frictional coefficients. The range between least applied force needed to couple bow to load during sticking and maximum permitting uncoupling following sticking provides the generous tolerance, variable but typically in the ratio of 1 to 10, that makes the bowed string so flexible in performance. Domains of string behavior recognized by players are related graphically to bowing parameters. An electromagnetic method for observing particle velocity in the string reveals small but significant ripples caused by forces at the bow that the idealized explanation ignores. In one very flexible string, force exerted on the bridge varied approximately inversely with frequency out to the 15th harmonic, whereas for a string equivalent to a gut G for violin force became zero near the 7th. Elastic effects are considered, and it is suggested that in strings, either solid or wound, inharmonicity of 0.1 cent per square of mode number will not perceptibly degrade bowed‐string performance.

ISSN:0001-4966    

DOI:10.1121/1.1913322

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The performance of real‐time speech recognition systems is observed to depend upon the environments in which they are used. Human factors, caused for example by operator frustration, significantly affect success rates. A set of experiments with a word recognition system is described which quantifies this change, whilst the system is being used to control the movement of a displayed cross on a screen.

ISSN:0001-4966    

DOI:10.1121/1.1913325

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The assumption that the direction of ear superiority in dichotic listening to sounds varies as a function of the number of stimulus transitions within sound sequences was tested in two experiments on 36 right‐handed students. In each sequence, three sounds which varied in terms of either frequency or duration were employed. Subject's task was to report the sequences by ear. The results showed that as the number of frequency or duration transitions increased from zero to two, ear superiority shifted from left to right. The shift from left to right ear superiority as a function of the increase in the complexity of temporal patterning suggests that perception of temporal patterns might be one of the underlying mechanisms in speech perception.

ISSN:0001-4966    

DOI:10.1121/1.1913326

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Listeners heard vowels in syllabic contexts, presented dichotically at S/N (signal‐to‐noise) ratios of 0 and −10 dB, and their responses were analyzed in terms of individual ears. In the most‐adverse listening condition the level of correct response in the right ear was 6% higher, on the average, than that obtained in the left ear; there was no difference between ears in the more‐favorable listening condition.

ISSN:0001-4966    

DOI:10.1121/1.1913327

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The present work considers enhancement of mass transport resulting from superimposing an ultrasonically induced convective transport on a diffusional transport. As a result of the nonlinearities in the Navier‐Stokes equation, a time‐dependent secondary flow called acoustic streaming can be produced when an acoustic wave is passed through a medium. Between adjacent vortices or cells, molecular diffusion is the only means of transport; however, within each cell, mass transport is primarily by convection. Increases in the rate of mass transfer of the order of 150% above the normal diffusional flux were found. The theoretical analysis and results presented have application to systems in which ultrasonics may be used to increase mass transfer through membranes (e.g., dialysis), and to increase the efficiency of very active catalytic systems and of solid‐liquid extraction systems.

ISSN:0001-4966    

DOI:10.1121/1.1913328

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Theoretical calculations and experimental measurements for an acoustic wave bound to and guided by a fluid layer between two semi‐infinite isotropic elastic solids are reported. Discussion of theory includes wave propagation characteristics, mode existence criteria, and the distribution of elastic energy in the structure, treating separately the cases where the geometry is symmetric and nonsymmetric about a plane of bisection. Experimental results include measured propagation characteristics for the layered geometry and a device realization of this particular structure.

ISSN:0001-4966    

DOI:10.1121/1.1913329

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

As is well known, a small compressive disturbance in an elastic gas grows into a shock wave in finite time. If the gas is viscoelastic or has internal degrees of freedom, this result is no longer true unless the initial amplitude of the disturbance is larger than acritical amplitude. This article investigates the effect of diffusion on the growth and decay properties of small disturbances in a mixture of elastic gases. It is shown that a critical amplitude exists for the mixture. Thus, diffusion can be thought of as having a stabilizing effect in that not all compressive disturbances will grow into shock waves.

ISSN:0001-4966    

DOI:10.1121/1.1913330

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP