## Frequency or pitch

• Pitch is a musical term with a meaning which is very close to the meaning of the scientific term frequency
• The scientific term frequency is slightly more specific than the normal use of the word frequency, which means simply "how often something happens".
• It means the number of times an event occurs in a period of time.
• Hertz (abbreviated to Hz), is the scientific unit for the number of times an event happens in one second.
• For example, an electric current which alternates its direction 50 times each second is referred to as 50Hz
• A computer with a clock tick 90 million times a second is called a 90MHz machine ("M" being short for the prefix "Mega" meaning a million)
• H. R. Hertz was a physicist in the 19th Century (1857-1894)

• A note (in my definition) has one, and only one, pitch.

• The pitch or frequency can be stated in a number of different ways:
• The scientific way, e.g. "512Hz"
• This method is absolutely precise and accurate
• There is no possibility of error or inaccuracy
• As a musical description, e.g. "Treble C" or, " c' ", or "The third space on the treble-clef", or "C above middle C"
• This method is not precise and not accurate
• There is scope for misunderstanding
• If the instruction is understood, the exact pitch is imprecise and will depend on the tuning of the instrument
• An extract from musical notation:
• This method is precise but not accurate
• There is very little scope for misunderstanding
• The exact pitch is still imprecise

• A note is produced by a very rapid, regular pulsing.
• If you take a drum sound with a beat every second
• Then speed it up to 512 times per second
• You will perceive it as a note of 512Hz, as in the example above

• There are a lot of examples in real life that you will already be familiar with:
• The high-pitched whine of a mosquito is caused by the wings beating at over 1000 times a second
• The sound of a propeller starting up, at first a slow thump, which turns into a low noise, and finally into a whine
• The note produced by a razor or a vacuum cleaner is caused by the regular movement of a blade or motor.
• The best example is probably a electronic metronome, which uses the same oscillating circuit to produce a beat as to produce a tuning note. A tuning note is produced by getting the circuit to oscillate at 440Hz.

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