Joan Clarke, woman who cracked Enigma cyphers with Alan Turing. Read more about sharing. Joan Clarke's ingenious work as a codebreaker during WW2 saved countless lives, and her talents were formidable enough to command the respect of some of the greatest minds of the 20th Century, despite the sexism of the time.
A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. It is defined as the interval between two adjacent notes in a 12-tone scale (e.g. from C to C â¯).9-tone equal temperament distinguishes between the chromatic and diatonic semitones; in this tuning, the chromatic semitone is one step of the scale (play 63.2 cents (helpÂ·info)), and the diatonic semitone is two (play 126.3 cents (helpÂ·info)).
But then from A-880Hz to A-1760Hz is also 12 semitones. In one case you have a change of 440Hz spread over 12 semitones. In the other you have a change of 880Hz spread over 12 semitones. So as you go up the pitch scale, each semitone consists of a slightly larger change in frequency than the semitone below it. That is why the pitch system is non-linear. There is no set number of (change in) Hz per semitone.