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# Acoustics

George

Posts : 290
Join date : 2017-11-26

I have just read about acoustics in The Concise Oxford Dictionary of Music.

As a branch of physics, acoustics is concerned with sounds, what they are and how they are produced, transmitted and received. But it is also a subject of interest to musicians, who may, for example, wish to know how suitable the architecture of a concert hall or recital room is to the performance of music. And they are definitely interested in such properties of sound as loudness, frequency and timbre.

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Sophie

Posts : 43
Join date : 2017-12-02
The frequency of musical note corresponds to its pitch. I suppose one could say that frequency is an objective attribute of a sound wave while pitch is a subjective psychological perception of it. And the octave interval can be considered a fundamental property of pitch: the ear (or rather the auditory cortex of the brain) perceives sound of a frequency twice that of another as something distinctive. Then, if the octave interval is divided into the twelve notes of the chromatic scale, equally tempered, the ratio between two notes a semitone interval apart is $2^{\frac1{12}}$, that is to say, an increase in frequency of approximately 1.059463 Hz corresponds to an elevation of pitch by one semitone.

George

Posts : 290
Join date : 2017-11-26

The frequencies of middle C and concert A are sometimes chosen to be 256 Hz and 440 Hz respectively. On an equally tempered scale with the octave ratio fixed at 2, however, the two notes, separated by an interval of nine semitones, can no longer both take those values. If middle C is chosen to be 256 Hz, then concert A will be approximately 430.54 Hz, while if concert A is chosen to be 440 Hz, then middle C will have to be approximately 261.63 Hz.

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Sophie

Posts : 43
Join date : 2017-12-02
Intervals can be added by adding their constituent semitones, modulo an octave (meaning, for example, the major-ninth interval is the same as the interval of a major second (i.e. a whole tone)). The set of all intervals under addition modulo an octave is then a cyclic group of order 12! Two of its generators are the intervals of the perfect fourth and the perfect fifth – from which we get the circle of fourths and circle of fifths in musical theory. One can also have the circle of minor seconds and the circle of major sevenths, but these are not quite so interesting, being simply derived by going up and down by semitones (modulo and octave) respectively. There are no other circles in music theory: these are the only four possible ones, as they are precisely the generators of the cyclic group of order 12. (If one goes up by minor thirds, say, one will only get four of the twelves notes in the chromatic scale. The subgroup generated by the minor-third interval is one of order 4.)

George

Posts : 290
Join date : 2017-11-26

There is so much more connection between physics/mathematics and music than people generally realize. Thus, the loudness of a music note is associated with the amplitude of the corresponding sound wave, and its timbre is due to the superposition of various overtones produced by the instrument playng the note.

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Vicky

Posts : 54
Join date : 2017-11-27
Linguists are also interested in the science of acoustics, especially in the way speech sounds are produced. Phonetics is the study of the mechanics of speech production (as opposed to phonology, which is the study of the range of speech sounds (phonemes) in individual languages or language systems).