Number of samples or snapshots taken of a particular signal in a given amount of time (usually one second). Higher sampling rates result in more pieces of the true signal. When a sufficient number of pieces are generated, the pieces meld together to form a very close approximation of the original, continuous signal. Such an approximation, when done with a high enough sampling rate, has a high enough resolution a to be identical to the original signal to human senses. ll analog data converted to digital data is sampled. The samples are then given a value that can be stored digitally. Later the samples are recreated from the digital data and the samples are blended together to form a complete, continuous analog signal (this is the job of the digital-to-analog converter or DAC). he sampling rate used for compact discs is 44.1 kHz (44,100 cycles per second or, in this case, samples per second). The sampling rate must be at least two times the maximum frequency signal to be reproduced. Thus for a CD to reproduce audio up to 20 kHz requires a sampling rate of 40 kHz (with the standard actually set at 44.1 kHz). he amplitudes of the samples taken are recorded with a certain number of bits (a single bit is a single one or zero in digital information transfer; the smallest part of a digital signal). The process of converting the sample amplitude to bits of data is called quantisation. uantisation takes the maximum amplitude or height of a given signal and divides it into a number of small pieces that are stacked on top of each other to reach the highest amplitude. The actual amplitude value falls somewhere within on of those stacked blocks. That block is then given as the height of the signal at that sample. If the blocks used are large, the amplitude values are not very accurate when reproduced (the resolution is low). If the blocks are very small, their values are closer to the true values of the amplitude at given samples resulting in a more precise reproduction. hink of a ruler that only measures in inches. If you draw a line that is three and a half inches in length, when it is quantised it will be given as three inches. If the quantisation blocks are smaller, say one eighth of an inch, then the approximated value is very close to the real value. In digital reproduction, the quantisation is determined by the number of bits used to record the quantisation blocks. With more bits, there can be more blocks resulting in signal heights more closely resembling the actual values. CD digital audio uses 16 bits to represent the height or amplitude of each sample. These 16 bits allow for the use of 65,536 blocks to form the quantisation (two to the sixteenth power – there are two possible values, one and zero, that can be combined across sixteen spaces to form data). Most professional recordings use quantisation values of 20 to 24 bits (resulting in 1,048,576 blocks and 16,777,216 blocks respectively – obviously much more precise than the 16 bits used for CD audio). he sampling rate combined with the quantisation affect the potential maximum quality of an analog signal converted to and then later reproduced from digital data. Higher fidelity audio systems would use higher sampling rates combined with higher quantisation to create a more accurate representation of an analog wave signal and thus be able to produce a better quality output closer to the original signal. he difficulty with using higher sampling rates and quantisation bit word lengths is that the resulting file size becomes increasingly large making storage of very high-fidelity digital audio a problem. This is the reason the format used for CD audio was chosen, it is a good compromise between ultimate sound quality and file size affecting storage issues and the amount of audio that can be held. ome discussion is circulating regarding a new, high-definition audio format using DVD technology to hold data encoded at a 96 kHz sampling rate with a quantisation of 20 to 24 bits resulting a vastly superior audio reproduction format compared to standard CD.