ABSTRACT
Also called the sampling rate. The frequency or rate at which an analog signal is sampled or converted into digital data for storage or eventual playback, with the reading expressed in Hertz (Hz). For example, the compact disc’s sampling rate is 44,100 Hz (44.1 kHz). Since the earliest commercial digital audio recorders used a standard helical-scan video recorder for storage, it was necessary to have a fixed relationship between the sampling frequency and the horizontal video frequency. This allowed those frequencies to be derived from the same master clock by frequency division. For the NTSC 525-line television system used in the U.S., a sampling frequency of 44,055.94 Hz was selected, whereas for the European PAL 625-line system, a frequency of 44,100 Hz was chosen. The 0.1 percent difference shows up as an imperceptible shift in pitch. It is important to remember that there are other rates than those used by the compact disc, with common examples being 32 kHz, 48 kHz, and even 50 kHz. Those are mostly used by digital recording devices.
