Abstract
The investigations focused on the binaural perception of amplitude modulated (AM) and frequency modulated (FM) signals. They are comprised of two experiments. In the first experiment binaurally perceived (matched) modulation depth for AM signals was determined under diotic conditions (i.e. for the same values of modulation depth coefficient, m, presented to the left (ml) and right (mr) ears) and under dichotic conditions (i.e. for different values of these coefficients ml 6 = mr). The measurements were made for the interaural differences in modulation depth coefficient Δm, changing from 0 to 100% and a few selected modulating frequencies (4, 64 and 128 Hz) and carrier frequencies (250 and 1000 Hz). In the second experiment binaurally perceived (matched) frequency deviation of FM signals was determined under diotic conditions (i.e. for the same values of frequency deviation, Δf, presented to the left (Δfl) and right (Δf) ear (Δfl = Δfr) and under dichotic conditions (i.e. for different values of this deviation (Δfl 6 ≠ Δfr)). The measurements were made for the interaural differences of frequency deviation changing from 0 to 20 Hz; a few selected modulating frequencies (32, 64 and 128 Hz) and carrier frequencies (500 and 1000 Hz). It was found in Experiment I that for small interaural differences in modulation depth, Δm, the binaurally perceived modulation depth, m, is equal to the arithmetic mean of the depths presented to the left and right ears, whereas for large values of Δm, the value of m is smaller than the mean. The results of Experiment II revealed that the binaurally perceived frequency deviation is a linear function of interaural differences of this deviation and is equal to the arithmetic mean of deviations presented to the left and right ears.References
[1] L.R. Bernstein and C. Trahiotis, Lateralization of low-frequency, complex waveforms: The use of the envelope-based temporal disparities, J. Acoust. Soc. Am. 77, 1868-1880 (1985a).
[2] L.R. Bernstein and C. Trahiotis, Lateralization of sinusoidally amplitude-modulated tones: Effects of spectral locus and temporal variation, J. Acoust. Soc. Am., 78, 514–523 (1985b).
[3] J. Blauert, Spatial hearing, The MIT Press, Cambridge, Massachusetts 1983.
[4] J.J. Groen, Super- and subliminal binaural beats, Acta Otolaryngol., 57, 224–231 (1964).
[5] X. Gu, B.A. Wright and D.M. Green, Failure to near binaural beats below threshold, J. Acoust. Soc. Am., 97, 701–703 (1995).
[6] L.M. Heller and C. Trahiotis, Extents of laterality and binaural interference effects, J. Acoust. Soc. Am., 99, 3632–3637 (1996).
[7] R.P. Hellman and J.J. Zwisłocki, Monoural loudness function at 1000 cps, and interaural summation, J. Acoust. Soc. Am., 35, 856–865 (1963).
[8] G.B. Henning, Some observations on the lateralization of complex waveforms, J. Acoust. Soc. Am., 68, 446–454 (1980).
[9] G.B. Henning and J. Ashton, The effect of carrier and modulation frequency on lateralization based on interauralphase and interaural group delay, Hear. Res., 4, 185–194 (1981).
[10] T. Houtgast and H.J. Steeneken, Review of the MTF concept in room acoustics and its use for estimating speech intelligibility in auditoria, J. Acoust. Soc. Am., 77, 1061–1077 (1985).
[2] L.R. Bernstein and C. Trahiotis, Lateralization of sinusoidally amplitude-modulated tones: Effects of spectral locus and temporal variation, J. Acoust. Soc. Am., 78, 514–523 (1985b).
[3] J. Blauert, Spatial hearing, The MIT Press, Cambridge, Massachusetts 1983.
[4] J.J. Groen, Super- and subliminal binaural beats, Acta Otolaryngol., 57, 224–231 (1964).
[5] X. Gu, B.A. Wright and D.M. Green, Failure to near binaural beats below threshold, J. Acoust. Soc. Am., 97, 701–703 (1995).
[6] L.M. Heller and C. Trahiotis, Extents of laterality and binaural interference effects, J. Acoust. Soc. Am., 99, 3632–3637 (1996).
[7] R.P. Hellman and J.J. Zwisłocki, Monoural loudness function at 1000 cps, and interaural summation, J. Acoust. Soc. Am., 35, 856–865 (1963).
[8] G.B. Henning, Some observations on the lateralization of complex waveforms, J. Acoust. Soc. Am., 68, 446–454 (1980).
[9] G.B. Henning and J. Ashton, The effect of carrier and modulation frequency on lateralization based on interauralphase and interaural group delay, Hear. Res., 4, 185–194 (1981).
[10] T. Houtgast and H.J. Steeneken, Review of the MTF concept in room acoustics and its use for estimating speech intelligibility in auditoria, J. Acoust. Soc. Am., 77, 1061–1077 (1985).
