Musical Instrument Digital Interface, - Hol.gr

Different Quantization and Sampling Rates
In diagram (A) and (B) the sampling rate is the same, but the quantization resolution is better in diagram
(B). In diagram (C) & (D), the sampling rate has been doubled and the bit resolution has been increased in
diagram (D). What a dramatic difference the sampling rate and bit resolution can make on recreating an
acoustic waveform.
The Nyquist Theorem determines that the bandwidth of any digital sampling length will always be onehalf
of the sampling rate. This means that a sample taken at a rate of 44k would have 22k (22,000)
pictures or snap shots of the waveform in one second of time. A higher rate will have more samples per
second and will also take up more computer memory. The Nyquist Frequency is the frequency of the
highest component of a sound and the Nyquist Rate is twice the Nyquist Frequency.
More computer memory is also used when the bit resolution is higher (16 bits to represent a number
verses 8 bits). Computer memory and the content that is being sampled will determine the sampling rate
and bit resolution to use. For example, sounds that do not have a high frequency content could be sampled
at a lower rate and still imitate most of the same fidelity as the original sound.
It is important that the signal that is being sampled does not have frequencies above the Nyquist
Frequency. Every time that a sample is made, there is also duplicates of the signal that are also created that
are called Folding Components.