Freethought & Rationalism Archive

anotherfailure · 04-20-2003, 06:57 PM

Why are we inclined to call some sounds "music" and others not?

Further, why is percussive music not based on a note scale, like tonal music? What makes the distinction between a "drum" sound and a "tone" sound, in our brains?

scigirl · 04-20-2003, 07:41 PM

It's all about how the brain processes the information, and I don't think we really know the answer. Here's some info from my neuroscience book:

Quote:

Sounds that are especially important often have a highly ordered temporal structure. In humans, the best example is speech. Behavioral studies in cats and monkeys show that the auditory cortex is especially important for processing temporal sequences of sound. If the audotory cortex is ablated in these animals, they lose the ability to discriminate between two complex sounds that have the same frequency components but differ in the temporal sequence of the components.

That really doesn't answer your question does it!

scigirl

Undercurrent · 04-20-2003, 07:51 PM

Quote:

Originally posted by anotherfailure
What makes the distinction between a "drum" sound and a "tone" sound, in our brains?

The eigenvalues of the Lapacian on the associated domain. The 1-D wave equation for a vibrating string or a column of air in a pipe results in solutions such that there is one solution of lowest frequency, and all other solutions have frequencies that are whole multiples of that lowest frequency.

On a square membrane (drum), on the other hand, the solutions are such that higher-frequency solutions oscillate at square-root-of-whole-number multiples of the lowest frequency. For circular drums, the frequencies of the fundamental solutions are related through an even more complex relation.

It seems like the brain is configured to figure a wave that its spectrum contains a lowest frequency and only integer multiples thereof as being a "tone", and one with frequencies all over the place as a "drum" sound.

As for why some sequences of tones are called "music" and some are not, the theory of PDEs is somewhat more silent.

(Edited to add gratuitous link to Isospectral Manifolds , which are only tangentailly related, but cool nonetheless)

scigirl · 04-20-2003, 07:51 PM

Ok here's some more info about how we can distinguish different types of sounds (although still not really answering your question either!):

Quote:

As early as the first half of the eighteenth century, musical composers such as Tartini and Sorge discovered that upon playing pairs of tones, other tones not present in the original stimulus are also heard. These combination tomes, fc, are mathmatically related to the played tones, f1 and f2 (f2 > f1) by the formula:

fc = mf1 + or - nf2

where m and n are positive integers...Modern experiments indicaet that this distortion product is actually due to the nonlinear properties of the inner ear...resulting from the properties of the mechanical linkage of teh transduction apparatus of the hair cells. By moving the hair bundles sinusoidally with a metal-coated glass fiber, Husdpeth and co-workers found that the hair bundle exerts a force at the same frequency. However, when two sinusoids were applied simultaneously, the forces exerted by the hair bundle occured not only at the primary frequencies, but at several combination frequencies as well.

Apparently, when we hear different tones, we are paying the price in distortion for an exquisitly fast and sensitive transduction mechanism.

scigirl

Majestyk · 04-20-2003, 09:31 PM

As I've heard it stated before. Music is noise with structure. Our brains anticipate upcoming sounds based on this structure and are pleased when rewarded with a sound that does not greatly deviate from that which was anticipated. Here's a related link that talk's about structure and pyschological events relating to the timing of music from the conductor's perspective.

04-20-2003, 06:57 PM	#1
anotherfailure Junior Member Join Date: Feb 2003 Location: USA Posts: 17	Music and Sound Why are we inclined to call some sounds "music" and others not? Further, why is percussive music not based on a note scale, like tonal music? What makes the distinction between a "drum" sound and a "tone" sound, in our brains?

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04-20-2003, 09:31 PM	#5
Majestyk Veteran Member Join Date: Mar 2003 Location: Northeast Ohio Posts: 2,846	As I've heard it stated before. Music is noise with structure. Our brains anticipate upcoming sounds based on this structure and are pleased when rewarded with a sound that does not greatly deviate from that which was anticipated. Here's a related link that talk's about structure and pyschological events relating to the timing of music from the conductor's perspective.

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