programming with max/msp - Virtual Sound

1.2
8
Theory
Let’s look at a table (taken from Bianchini, R., 2003) of the correspondences
between the physical features of sound, musical parameters, and perceived
sonority.
CHARACTERISTIC PARAMETER PERCEPTUAL SENSATION
Frequency Pitch High � Low
Amplitude Intensity Forte � Piano
Waveform Timbre Sound color
TABLE A: correspondences between sound characteristics, musical parameters
and perceived sonority.
FREQUENCY
Paragraph 1.2 - Frequency, amplitude, and waveform
Frequency is the physical parameter that determines the pitch of a sound, that
is, it is the feature that allows us to distinguish between a high-pitched sound
and a low-pitched sound. The range of frequencies that is audible to humans
extends from about 20 to about 20,000 hertz, that is to say, from about 20 to
about 20,000 cycles per second. 6 (We’ll define cycles per second in a moment.)
The higher the frequency of a sound, the higher its pitch will be.
But what do we mean by hertz or “cycles per second”? To understand this, we
refer to the definition of sound given by Riccardo Bianchini:
“The term ‘sound’ signifies a phenomenon caused by a mechanical perturbation
of a transmission medium (usually air) which contains characteristics that can be
perceived by the human ear. 7 Such a vibration might be transmitted to the air,
for example, by a vibrating string (see fig. 1.6). The string moves back and forth,
and during this movement it pushes the molecules of air together on one side,
while separating them from each other on the other side. When the motion of
the string is reversed, the molecules that had been pushed together are able to
move away from each other, and vice versa.
The compressions and expansions (that is to say, the movements of air molecules)
propagate through the air in all directions. Initially, the density of
6 The highest frequency that someone can hear varies from individual to individual. Age is also a
factor. As we get older, our ears become less sensitive to high frequencies.
7 There are many theories about the nature of sound: Roberto Casati and Jérôme Dokic argue that
the air is a medium through which the sound is transmitted, but that sound itself is a localized
event that resonates in the body, or in the mechanical system that produces the vibration. (Casati,
R., Dokic, J. 1994). Another point of view is expressed by Frova: “with the term ‘sound’, one
ought to signify the sensation, as manifest in the brain, of a perturbation of a mechanical nature,
of an oscillatory character, which affects the medium interposed between source and listener.”
(Frova, A., 1999, p.4).
from “Electronic Music and Sound Design” Vol. 1 by Alessandro Cipriani and Maurizio Giri
© ConTempoNet 2010 - All rights reserved