Jozef J. Zwislocki

Theory of Temporal Auditory Summation

A theory of temporal auditory summation is developed and applied to the threshold of audibility for various temporal patterns of pulses and sinusoidal vibrations. The theory is based on the assumption of an exponential decay of neural excitation and, for the threshold of audibility, it includes only one time constant. Various factors that may affect temporal auditory summation are discussed. It is shown that the same theory applies to muscle contractions.

Absolute scaling of sensory magnitudes: A validation

The hypothesis that, in magnitude estimation and production, subjects tend to pair numbers with sensation magnitudes on absolute rather than ratio scales is tested experimentally. This implies that not only sensations, but also numbers acquire absolute psychological magnitudes. The specific experiments are performed on loudness and line lengths. The latter reveal that the subjective magnitudes of numbers are formed before the age of 6 and do not change after that age. It is suggested that the absolute coupling of numbers with sensation magnitudes originates from the concept of numerosity where numbers have absolute meanings. This work was supported by N1H Grant NS-03950.

Analysis of the Middle‐Ear Function. Part I: Input Impedance

A quantitative theory of the middle‐ear acoustics is developed and expressed in terms of an electric analog. The analog network is based on the functional anatomy of the middle ear. The numerical values of its elements are derived from impedance measurements on normal and pathological ears and from anatomical data. It is shown that the input impedance of the analog agrees within the experimental error with the acoustic impedance at the eardrum, and that changes in analog parameters corresponding to known anatomical changes produce the same effect on its impedance characteristics as measured at the eardrum.

Monaural Loudness Function at 1000 cps and Interaural Summation

A monaural loudness function is determined for 1000 cps and compared to a previously obtained binaural loudness function. Although the monaural function appears to have a somewhat smaller exponent than the binaural one, the empirical evidence does not permit rejection of the hypothesis of a simple interaural loudness summation. The psychophysical methods of magnitude estimation with and without a designated standard and of magnitude production without standards are used. A combination of magnitude estimation and production without standards is accepted as a method with minimum bias and classified under a more general methodological category called “psychological magnitude balance.”

Temporal Summation of Loudness: An Analysis

A quantitative psychophysiological theory is developed for loudness level and loudness as a function of stimulus duration. It is based on the psychophysical as well as neurophysiological evidence that the apparent temporal summation of acoustic energy is a result of neural summation at a high level of the auditory system. The theory shows how this can be achieved in spite of a nonlinear relationship between sound intensity and neural excitation. The temporal decay of neural firing preceding the final stage of temporal summation seems to be responsible for overcoming the nonlinearity.

Short-term adaptation and incremental responses of single auditory-nerve fibers

In response to tone bursts of constant sound intensity, mammalian auditory-nerve fibers produce a maximum firing rate at onset, followed by an adaptation to a quasi-steady firing rate within about 150 msec. On the basis of two fundamental findings, it appears that the adaptation is additive, or linear, in nature and does not result from a multiplicative gain change. Basically, a given increment in stimulus intensity produces the same change in firing rate before and after the adaptation. In addition, the relative amount of adaptation, i.e. the ratio of driven onset firing rate to driven steady-state firing rate, is independent of tone intensity. Nonlinear effects that appear in the experimental results may be accounted for by two static nonlinearities, one preceding and one following the linear adaptation stage.

Loudness Function of a 1000‐cps Tone in the Presence of a Masking Noise

Loudness levels of a partially masked 1060‐cps tone are determined by loudness‐balance procedures and, indirectly, by the methods of magnitude estimation and production. It is shown that loudness balances obtained by the method of adjustment are consistent with the loudness judgments obtained by the combined method of magnitude estimation and production, called method of numerical magnitude balance. The final results are in good agreement with those of other investigations in which balanced procedures were followed.

On the Effect of Practice and Motivation on the Threshold of Audibility

The thresholds of audibility for 100 and for 1000 cps have been measured on five groups of originally naive listeners by various experimental techniques. All the experiments showed improvement of the threshold with practice. The improvement was greater at 100 cps than at 1000 cps. Pretraining at 1000 cps did not affect the threshold change at 100 cps. The improvement of the threshold with practice was enhanced considerably by reward and feedback.

Acoustic Attenuation between the Ears

In an investigation of the acoustical insulation between the ears, various earphones and obturating devices were used. Bone conduction was shown to be chiefly responsible for the acoustical leakage between the ears. Conditions were determined under which interaural insulation could be increased considerably. Most of the measurements were performed with a compensation method which appears to give more precise results than methods previously used, and which permits phase measurements.

Five decades of research on cochlear mechanics

A review of Békésys experiments on postmortem preparations shows the fundamental features of cochlear macromechanics. Early mathematical theory was able to explain Békésys observations in terms of the hydrodynamics of surface waves and to account for some experimental artifacts. More recent experiments in vivo have shown that the cochlear frequency analysis is sharper than observed by Békésy and may occur in two interacting stages. It is suggested that the second stage may result in part from a resonance of hair-cell stereocilia loaded by the mass of the tectorial membrane, and it is calculated that the damping is small enough to allow such a resonance. The resonance would make the basilar membrane with the organ of Corti appear as a fourth- rather than a second-order system.