EE 284 Lecture 1: mynotes
Document Summary
The lower the bandwidth, the lower the quality. Voice quality : similar to the mos value there exists a psqm(perceptual speech quality measurement) this is an algorithm that attempts to faithfully represent human judgement and perception processes. The result of psqm testing is a psqm score that can be converted to an mos value. Psqm testing involves the algorithmic comparison between the output signal of a communications system (such as a voice coder/decoder) and a known input signal. Tests are conducted with a variety of different speech samples that may have been produced artificially or by real speakers. If produced artificially, then the speech samples should be generated according to itu-t recommendation p. 50. According to the nyquist theorem we can get back a signal only if we sample it at a rate twice its maximum frequency. After the sampling the samples has to be represented by some number of bits.
