The Nyquist-Shannon sampling theorem states that in order to perfectly reconstruct a signal, the sampling frequency must be greater than twice the bandwidth of the signal being sampled. If lower sampling rates are used, the original signal’s information may not be completely recoverable from the sampled signal. For example, if a signal has a bandwidth of 300Hz, the sampling frequency must be greater than 600Hz. If the sampling frequency is too low, aliasing can occur.
Aliasing is a major concern in the when using analog-to-digital conversion while recording audio. Improper sampling of the analog signal will cause high-frequency components of the signal to be aliased with genuine lower-frequency components. If this happens, the digital-to-analog conversion will create an incorrectly reconstructed signal.