Re: indefinite pitch


Subject: Re: indefinite pitch
From: Kevin Austin (kevin.austin@videotron.ca)
Date: Fri Oct 07 2005 - 00:56:23 EDT


You enter the realms of physics and psychoacoustics, and
(re)introduce a fascinating concept / dilemma.

The idea that "pitch" is a perceived 'quality' is one that
traditional 'music school' ear-training stays far away from, IME.
Most (traditional) ear-training courses restrict themselves to the
middle 2 1/2 to 3 octaves of the piano keyboard.

A game I have enjoyed in class is to play a cluster of five notes
(with the sustain pedal down) at the bottom of the piano and ask the
class whether they perceive pitches or 'tone color'. The
psychoacoustician points out that since there are several
fundamentals within each others' critical bandwidth, they will not be
able to be separated / segregated, but rather a 'spectral complex'
will be reported.

Reduce the cluster to 4 notes, 3 notes, 2 notes ... When does
'spectrum; give way to 'pitch'?

Play the lowest A on the piano with the sustain pedal depressed.
(Sustain pedals are often depressed, but that's another thread.)
Repeatedly play the note at about 1/2 second intervals, and do so for
about 10 minutes. At some time in this exercise, the "note" comes
apart. For many people, as integrated quality becomes segregated --
"one pitch" becomes "many pitches".

Was the original 'pitched' sound an integrated pitched sound or not?

My view of this is that it has less to do with the sound than the
perception of the sound, and the 'answer' lies not in 'the sound',
but in the psychoacoustic processes involved in perceiving sound(s).

Regarding the cymbal question (not so simple), a place to start
regarding some contemporary thought is with the term (Google) "pitch
centroid" (see more extensive intro below).

Best

Kevin

You will need to forgive the authors who may think that vowels may be
spectral. <<<<8-()>>>>>>

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pdf file: www.phys.unsw.edu.au/~jw/reprints/SchWolTarICMPC8.pdf

Spectral centroid and timbre in complex, multiple instrumental textures

Emery Schubert*, Joe Wolfe+, Alex Tarnopolsky+,
*School of Music and Music Education; +School of Physics
University of New South Wales, Sydney, Australia

ABSTRACT
This paper investigates the dependence of perceived timbral
brightness on pitch and spectral centroid for single notes and
pairs of simultaneous notes. In both cases, brightness is better
correlated with the spectral centroid fc than with the ratio of fc
to the pitches of the notes.

1. Introduction
In a steady tone, the timbre depends, among other things, upon
the power spectrum (the distribution of power as a function of
frequency). Many researchers believe that the timbral quality
of brightness correlates with increased power at high
frequencies (eg. the vowel sound Œee¹ sounds brighter than
Œoo¹). One simple quantification the distribution in the power
spectrum is the spectral centroid 1, fc.

What happens to the brightness of a musical note when the
pitch frequency (F0) is shifted? In most cases, a higher pitched
note has a somewhat higher fc than does a lower note played on
the same instrument. Does the higher fc of a high note produce
greater perceived brightness? Or does ...

++++++++++++++++++++++++++++++++++++++++++++++++++

At 00:17 -0400 2005/10/07, Eldad Tsabary wrote:
>Hello all,
>
>I would like your input regarding a terminology issue.
>
>When discussing a (definite) pitch sound object, with the use of
>correct terminology it is very easy to distinguish between the
>object¹s physical quality (fundamental frequency and partials - most
>prominently those belonging to the fundamental¹s integer-multiple
>frequencies) and its perceived quality (pitch).

>Describing a note as having a higher FREQUENCY than another is
>unmistakably understood as having two sound objects ­ one vibrating
>faster than the other (a physical phenomenon). Saying it has a
>higher pitch, on the other hand, is understood as a note being
>PERCEIVED higher.
>
>However, in the case of, let¹s say, a cymbal ­ we understand it to
>have a range of prominent frequencies ­ sort of a cluster ­ instead
>of a single fundamental (physical description). Would we consider a
>brighter cymbal to be PERCEIVED as a higher INDEFINITE PITCH
>(describing perceptual qualities rather than physical)? Do you find
>the term ³indefinite pitch² somewhat deceptive (a sound object
>either has pitch or doesn¹t?)
>
>If we accepted the term ³indefinite pitch² when would it not be
>applicable anymore? For example in white noise there is obviously no
>pitch of any kind. What about two different band-limited white
>noises? Does it make sense to refer to one being perceived higher in
>indefinite pitch than the other? Or would we simply use a term such
>as brighter (again, avoiding description of its physical qualities
>for now).
>
>Eldad



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