Physics - Period, frequency and pitch
Period, frequency and pitch
The frequency  of the sound wave is the number of complete cycles that
pass a point in a given time. Frequency is measured in hertz (Hz). A sound
source that is vibrating rapidly has a high frequency, for example 10 000
Hz. A source vibrating at a slower rate has a low frequency, for example 50
Hz. The frequency of vibration determines the pitch  of the sound.
Frequencies above 3000 Hz are quite highly pitched tones and if heard for
an extended time would soon become annoying.
On average, the human ear can detect sound frequencies between 20 and 20
000 Hz, although this does vary between individuals. Typically, as a person
ages they are less capable of detecting the higher frequencies of sound.
Usually this is not a problem as most everyday sounds are well below 2000
The period , T, of a wave is the time taken for one full cycle to be
completed. It is measured in seconds. By definition the period must be the
inverse of frequency.
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