How long does a digital recording last?

A digital recording does not attempt to record all of the original, continuous signal. The sound wave is first converted into an electronic signal by a microphone. Measurements of the signal intensity are then made at regular intervals (sampling). At each sampling point, the signal must be assigned a specific intensity from a set range of values (quantization). For example: the signal being measured is only allowed values between 0-255. If the signal has an intensity between 233 and 234, e.g. 233.5 it must be assigned a value of either 233 or 234. Using a greater range of possible assignments, e.g. 5000 instead of 256, increases the accuracy of the measurement. Sampling (i.e. measuring the signal) with greater frequency also increases the accuracy. In doing this, the original sound wave can now be described using only numbers. When playing a digital recording, the numbers are converted back into a continuous, analog signal. This electronic signal is then amplified and converted back into a sound wave by a loudspeaker.