Looking at the word “indefinite-pitched”, I realized I only had a basic idea about the nature of musical and nonmusical sound, and how this term relates to them. Along with many questions arising on how to classify a sound, I made a good turn towards musical acoustics.

“Musical acoustics is a unique area of study where “art” and “science” meet.” (University of Colorado Boulder, 2011)

One of the earliest discoveries in musical acoustics was made by Pythagoras who introduced mathematics to the field. According to Boethius, he first began his studies when he passed a blacksmith’s shop and heard the sound of a hammer on an anvil. He determined the simple arithmetic ratios of sounds, derived by observing them on his monochord. His knowledge was partly acquired from Egyptian priests, which suggests an even earlier origin. (Helmholtz, 1895:1)

In his grand work, the father of acoustics – Chladni (1809:2) describes the sound through arithmetics, mechanics and physiology. Helmholtz (1895:1) is one of the first to try to unite some of its different fields:

“In the present work an attempt will be made to connect the boundaries of two sciences … I mean the boundaries of physical and physiological acoustics on the one side, and of musical science and aesthetics on the other… The horizons of physics, philosophy, and art have of late been too widely separated, and, as a consequence, the language, the methods, and the aims of any one of these studies present a certain amount of difficulty for the student of any other of them.”

The many areas within musical acoustics, that is – its physics, physiology, psychology, philosophy and art, are all various ways to interpret a sound. I like the way Buck (1918:19-11) explained it in analogy with the various points of views we get when someone receives a blow:

“We might ask a lawyer for a legal opinion on the assault, a boxing expert for a technical description of the hit, a doctor for an appreciation of the damage, a moralist for a homily on self-control. But if we ask a psychologist … He will tell us that the blow itself was a stimulus, that the recipient then experienced an immediate sensation, followed at once (unless it was a knock-out blow) by the perception of the nature and cause of the sensation, and followed later by workings of the mind, which are called concepts, on the facts presented.

When we listen to music exactly the same process occurs. Something acts as a stimulus to our auditory nerve, producing the sensation of sound: there follows the perception of its nature, and we say to ourselves that it is a clarinet, or a barrel-organ, or C sharp; and the mind is immediately provided with material for concepts, and we pass into the realms of discrimination, memory, association, and so forth.

The whole question of the action of the stimulus is a matter for purely acoustical investigation; the question of sensation is partly acoustical and partly physiological; the questions of perception and concepts are entirely outside Acoustics …”

Due to these different points of view and interpretation, we will see that defining a sound as musical or nonmusical is not as simple as it seems.

Buck, P. C. (1918) Acoustics for Musicians. Oxford: The Clarendon Press
Helmholtz, H. L. F. (1895) On the Sensations of Tone as a Physiological Basis for the Theory of Music. (3rd ed.) London: Longmans, Green, and Co.