pitch (Richard M Warren )


Subject: pitch
From:    Richard M Warren  <rmwarren(at)CSD.UWM.EDU>
Date:    Thu, 3 Sep 1998 16:12:24 -0500

Dear List, I can't help jumping in on the discussion of pitch that developed into much broader issues. Al Bregman (27 August) comments on the need to keep in mind the distinction between the stimulus and its percept, since the same term can be used to describe both. He regretted the lack of appropriate verbal distinctions to separate the physical "SOUND 1" from the experience produced by SOUND 1 which he called "SOUND 2." On August 28, Dan Mapes-Riordan suggested that SOUND 1 should be referred to as "acoustic wave" and SOUND 2 referred to simply as "sound." The troublesome confusion of stimulus and percept is not restricted to physics and hearing. Newton, in describing his experiments with light, stated that it is incorrect to use such terms as red light and green light since "...the Rays to speak properly are not coloured." However, bowing to convenience and usage, he did go on to use color terms to describe the rays, and so I guess that unfortunately this inappropriate usage is bound to continue even though it can cause trouble in psychophysical judgments. Chuck Watson (27 & 28 August) divided "sense-based behavior" into two categories: (1) "Sensory Capabilities" (sensitivity, resolving power, and channel capacity); and (2) "Response Proclivities" (tendencies to assign specific verbal labels or to respond in specific nonverbal ways to specific stimuli). I agree wholeheartedly, but would like to take this a bit further, perhaps further than Chuck would want to go. I believe that sensory capabilities, or the limits of sensory detection and discriminability, are related pretty closely to limits imposed by physics and built-in physiological limits (I imagine there is no argument on this). However, once we cross this threshold and enter the domain of supraliminal stimuli, we are dealing with responses that are interpreted whenever possible in terms of corresponding events and conditions in the environment. Indeed, that is what our sensory systems are all about -- keeping us alive and interacting appropriately with our environment. Hence, there is an obligatory evaluation of all sensory input from exteroceptors in terms of external physical correlates (hence the confusion of SOUND 1 with SOUND 2). The topic of physical correlates as a basis for evaluating supraliminal sensory input leads me to comments made by Bill Hartmann (27 August) concerning quantitative judgments of sensation. He stated that the previous discussion concerning pitch had not distinguished between prothetic and metathetic continua, stating "Prothetic is associated with amount; metathetic is a point on a scale. Loudness is prothetic, we say 'More loudness.' Pitch is metathetic, we say 'Higher pitch.' We don't say, 'More pitch'." However, Stevens, Volkmann, & Newman (JASA, 1937, 8, 185-190) based their MEL scale of pitch upon direct quantitative judgments. They had their subjects adjust an oscillator to produce a pitch one-half that of the standard for frequencies ranging from 125 Hz to 12,000 Hz. Wever in his book "Theory of Hearing" (1949) noted that for frequencies below 5,000 Hz (that is, for pitches within the range of orchestral instruments) half frequency was judged half pitch. This suggests that the basic unit of musical scales (the octave) was used as the physical correlate for quantitative judgments of pitch. The only other experiment dealing with the scaling of pitch that I am aware of from another lab was that of Siegel, (Am J Psychol, 1965, 78, 615-620), who also found that frequencies one octave below the standards were judged to be half pitch (average of 48.9% for frequencies within the range of orchestral instruments). Since equal stimulus ratios produce equal subjective ratios (the hallmark of a "prothetic" continuum), a psychophysical power function can be constructed for pitch with an exponent of unity. Stephen Barrass (31 August) wrote that "colour hue," in addition to pitch, is a metathetic continuum. However, when a variety of colors (red, green, and blue) were each mixed with white (Warren, Perception & Psychophysics, 1967, 2, 448-452), I found that quantitative judgments of the respective hues were each inversely proportional to the square root of the percentage of white in the mixture, which corresponds to a "prothetic" power function with an exponent of 0.5 for each hue. [For a discussion of the evidence linking a square root rule to other types of visual magnitude judgments and to their physical correlate, see Warren, Psychol Rev, 1969, 70, 16-30.] Finally, the issue of the physical correlate for the power functions relating sound intensity to loudness is discussed at some length in my target article, "Measurement of Sensory Intensity," Behav & Brain Sci, 1981, 4, 175-223, and in Chapter 4 of my book, Auditory Perception: A New Analysis and Synthesis (Cambridge University Press) due out next month. McGill is running a new version of LISTSERV (1.8c on Windows NT). Information is available on the WEB at http://www.mcgill.ca/cc/listserv


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Electrical Engineering Dept., Columbia University