Metrology (latest).indd

Metrology, the science of measurement, is a most important activity in the recording of sound: what we record is in fact a measurement of the sound pressure or electronic signal amplitude we wish to preserve. In order to manipulate and record audio signals, we measure characteristics of the signal, generally amplitude as a function of time, and in some manner preserve that measurement. Analog magnetic tape stores a continuous magnetic pattern representation of the signal. Digital audio systems measure the signal amplitude, producing a list of discrete measurements at regular times that can then be treated like any other computer data. Since sound measurements are a function of time, we must have a way of measuring time as well. Once we have a reliable measure of time and the signal, we can manipulate the signal electronically or numerically and make changes to suit our artistic desires: we can process and mix sounds into sonic landscapes that never before existed. Appreciating that the quality of a recording depends on how well we are able to make a measurement is an important first step in the study of sound recording.