Re: vibrato (Laurent Demany )

Subject: Re: vibrato
From:    Laurent Demany  <Laurent.Demany(at)PSYAC.U-BORDEAUX2.FR>
Date:    Fri, 10 Apr 1998 11:55:23 +0200

Richard Warren wrote: >Since questions have been raised concerning vibrato, I would like to call >attention to a remarkable observation reported by Seashore (University of >Iowa Studies: Studies in the Psychology of Music, Vol. III, 1936, p. 105) >that has intrigued me for some time, and wonder if anyone knows of an >experimental verification of the phenomenon as described in the following >quote: >... in the normal vibrato which involves pitch, loudness, and timbre, >even the best ear can not isolate or identify these elements, to any >satisfactory degree, by direct hearing. We make the situation even more >critical and striking when we produce experimental tones in which we >present either a pitch or an intensity pulsation alone and ask the >musician to say which it is. Even under these circumstances, a good >musician is quite unable to say which is which, even when the extent >approaches the normal extent for pitch or intensity. For example, if we >have in one case an intensity wave of 5 decibels and in another a pitch >wave of a half-tone, he is almost as likely to call the intensity pitch, >or the pitch intensity, as to call them correctly.... Many musicians will >immediately take exception to this paragraph and say, "There is no danger >in my confusing pitch and intensity in the vibrato." That is just >another proof of the vitality of the illusion, because any one who has >such a conviction quickly can be disillusioned by submitting himself to >the test described. Seashore's observation has been verified for very small, and rather rapid, vibratos: It is impossible to discriminate a just-detectable sinusoidal FM from a just-detectable sinusoidal AM if the modulation rate exceeds about 5 Hz. But the discrimination is possible is the modulation rate is about 2 Hz. See: Demany, L., Semal, C. (1986). On the detection of amplitude modulation and frequency modulation at low modulation frequencies. Acustica, 61, 243-255. Moore, B.C.J., Sek, A. (1995). Effects of carrier frequency, modulation rate, and modulation waveform on the detection of modulation and the discrimination of modulation type (AM versus FM). JASA, 97, 2468-2478. Laurent Demany

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