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
- 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
- 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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