Originally Posted by tadekj
Not so fast. Digital signals converted to analog always have steps in the waveform, and it is why digital recordings always sound different that analog. Some people say that lack of full information in digital recording gives people headache because human brain must compensate lack of information in digital signal.(?????) Higher resolutions 96, 192, or SACD formats are smother, the steps are smaller but they are there.
This is a common misnomer on digital signals. You need to read the Nyquist Therom. When properly converted back to it's analog waveform there are no 'steps' in the waveform, it is the original waveform. The definition:
Nyquist's theorem: A theorem, developed by H. Nyquist, which states that an analog signal waveform may be uniquely reconstructed, without error, from samples taken at equal time intervals. The sampling rate must be equal to, or greater than, twice the highest frequency component in the analog signal.
There are very rigorous mathemetical proofs available on line, most involving fourier transformations, if you are so inclined.
This is why CDs have a sample rate of 44.1 khz, and that CD output is brickwalled at 22 khz (1/2 the sample rate).
Higher rez music allows for higher frequency content to be a part of the reconstructed waveform. Although in theory inaudible, it may have a bearing on the perception of a sound at lower frequencies. For example a vibrating string does not put out one frequency, but a fundamental frequency f(1) as well as overtones f(2), f(3), ..., f(n) where n--> infinity (the infinite series quickly converges and the higher level the overtone, the less a factor it is). (See solution to the problem of a vibrating string.) Overtones give a sound it's character, without overtones everything would sound the same. So the argument goes that higher frequency sounds even greater than 20 kHz provide for a better 'character' of sound for the content below 20 kHz , particularly for instruments in the upper midrange to treble range, (strings, cymbals, bells, female vocalists like Julie Andrews who could sing over a broad range of octaves, etc.) The debate of the worth of higher frequency content of SACD, DVD-A, or high rez digital files rages on. I like them, I'm not sure about the sonic benefit in term of frequency response, but generally those releases are better cared for in mastering, which at times justifies the use.
None of this has anything to do with the analog waveform being notched by sampling. That doesn't happen.