Biomedical subjects

A J Houtsma

Publications and source records attributed to A J Houtsma.

21 records · Page 2Linked to original sources

PubMed1980

Pitch of amplitude-modulated low-pass noise and predictions by temporal and spectral theories.

Pitch phenomena related to the periodic interruption rate of white noise have traditionally been regarded as evidence for time domain pitch processing in the auditory system since spectra of these signals are flat. Short-term spectra, however, contain information about the interruption rate. Melodic interval identification experiments were performed with sounds comprising low-pass filtered noise modulated by either a sine wave, a square wave, or a periodic narrow pulse wave. Melodic intervals were generated by varying the modulation frequency fm while the low-pass cutoff frequency fco of the noise was an experimental variable. The correct identification score shows a particular dependence on the ratio fco/fm for each type of modulation signal. Shapes and relative positions of performance functions are compared with predictions derived from an energy detector (time domain) model and a short-term power spectrum correlation (frequency domain) model, and are found to support the former more strongly than the latter. There is some evidence, however, for the existence of both types of processing in the auditory system.

Acoustic Stimulation↗

PubMed1980

Intensity perception XI. Experimental results on the relation of intensity resolution to loudness matching.

According to a recent extension of our theory of intensity perception [Lim et al., J. Acoust. Soc. Am 62, 1256-1267 (1977)], two stimuli are matched in loudness if and only if their intensities divide the respective dynamic ranges proportionally in terms of just noticeable differences. This study reports results of intensity discrimination and loudness matching experiments designed to test this prediction. Data were obtained over most of the dynamic range for three different types of sounds: a 1000-Hz tone in quiet, a 1000-Hz tone partially masked by a 2-octave band of noise, and spectrally flat wide-band noise. Of the five subjects tested, three produced results that had sufficient internal consistency to be useful for testing the predictions. For these subjects, the data and the theory were found to be reasonably consistent. Comparison with other studies, however, reveals that loudness matching results vary with matching paradigm by an amount that is significant with respect to the task of evaluating the theory. Hence, a rigorous test of the theory requires an improved understanding of the effects of matching paradigm.

Humans↗

PubMed1979

Musical pitch of two-tone complexes and predictions by modern pitch theories.

Most studies of the musical pitch of harmonic tone complexes have utilized signals comparing two or more successive harmonics. The present study provides systematic data on melodic interval recognition by three musically experienced subjects with sounds whose missing fundamentals were represented by two nonsuccessive harmonics nf0,(n + m)f0, delivered to separate ears. Data were obtained in the ranges 1 less than or equal to n less than or equal to 9, 2 less than or equal to m less than or equal to 4, and 200 Hz less than or equal to f0 less than or equal to 1000 Hz. The data are interpreted in the light of three theories, the "optimum processor theory," the "virtual pitch theory," and the "pattern transformation theory." For each theory, a constraint on preformance is proposed based on interference between the "analytic" and "synthetic" pitch perception modes. The former is obtained with large spacings between harmonics, where listeners are more likely to perceive harmonics as individual tones, each having their own pitch. This degrades the listener's ability to hear the fundamental pitch.

Humans↗