Lab Cat

23 Dec 2006

Chemistry is Everything – The Acoustics Edition

Filed under: Chemistry, Music, Science — Cat @ 4:54 pm

I believe that Chemistry is Everything.  I declaim this statement to my students and to my Mum all the time, especially after I’ve had to deal with some one who wants chemical-free food.  Chemistry is everywhere at least.  It is the air we breath, the food we eat, the water we drink.  That’s why I can have such an exciting time writing my blog.

I have always found it hard to explain music as chemistry though.  So how can I link love of my loves, music and chemistry.  There is the obvious that music alters our chemistry but that is more neuroscience.  Nope, I just read about acoustics* and realised how chemistry and music can interact.

Acoustics, according to my source*,

In its true sense are anything pertaining to the sense of hearing, but it is commonly used firstly as the branch of physics concerned with the properties, production and transmission of sound; and secondly with the quality of a building as regards its suitability for the clear hearing of music or speech. 

Which is also known as resonance. As well as the:

Sympathetic vibration of bodies capable of producing sound as soon as a pitch similar to that of the body or one of its overtones is heard

and the

Transmission of vibrations from the strings for a string instrument to a sounding board

Resonance is the rebound of sound from a solid structure such as wall of a hall or church.  As most musicians and lecturers will know some rooms are great at spreading sound and others are just dead.

This brings in the chemistry as the nature of the materials that determines if sound echoes too much, or too absorbent, deadening the sound.  Acoustic engineers can determine coefficients of absorption and other behavior for building materials. Once they have these coefficients, they can calculate out the sound fieldof a room.  It appears that very few materials, wood and special acoustic materials, have uniform absorptivity throughout the whole spectrum of sound. So that’s why all those medieval churches have such great acoustics. It is all that wood.  The acoustic behavior of materials is also important when building or refurbishing concert halls.

I find this very interesting, I had never thought how materials respond to sound before.  I knew that a lot of attention went into the materials used in concert halls and I know when we sing without a choir baffle with just a curtain, the sound is dead. Despite my interest in the physicochemical behavior of food I never thought about their acoustic behavior.  Hmm, I wonder if bread is a good acoustic material?

*At home with my parents, who have more books on more topics than I could imagine but that is a topic for another post, reading their Dictionary of Music. (Michael Kennedy, Concise Oxford Dictionary of Music Third Edition, 1980). 

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