Comparison of analog and digital recording
The dynamic range of an audio system is a measure of the difference between the smallest and largest amplitude values that can be represented in a medium.
[10] In contrast, digital PCM recorders show non-benign behaviour in overload;[11]: 65 samples that exceed the peak quantization level are simply truncated, clipping the waveform squarely, which introduces distortion in the form of large quantities of higher-frequency harmonics.
Consumer CD-R compact discs have a limited and variable lifespan due to both inherent and manufacturing quality issues.
Therefore, no such media deterioration takes place, and the CD will, with proper care, sound exactly the same every time it is played (discounting aging of the player and CD itself); however, this is a benefit of the optical system, not of digital recording, and the Laserdisc format enjoys the same non-contact benefit with analog optical signals.
The 16-bit digital system of Red Book audio CD has 216 = 65,536 possible signal amplitudes, theoretically allowing for an SNR of 98 dB.
This additional motion is added to the desired signal as noise, usually of very low frequencies, creating a rumbling sound during quiet passages.
The low-frequency response of vinyl records is restricted by rumble noise (described above), as well as the physical and electrical characteristics of the entire pickup arm and transducer assembly.
[19] This approach has several advantages since the digital filter can be made to have a near-ideal frequency domain transfer function, with low in-band ripple, and no aging or thermal drift.
[20]: 18 However, the digital anti-aliasing filter may introduce degradations due to time domain response particularly at lower sample rates.
The higher sample rates impose less restrictions on anti-aliasing filter implementation which can result in both lower complexity and less signal distortion.
Work done in 1981 by Muraoka et al.[23] showed that music signals with frequency components above 20 kHz were only distinguished from those without by a few of the 176 test subjects.
"[25] In blind listening tests conducted by Bob Katz in 1996, recounted in his book Mastering Audio: The Art and the Science, subjects using the same high-sample-rate reproduction equipment could not discern any audible difference between program material identically filtered to remove frequencies above 20 kHz versus 40 kHz.
This process is called quantization, and these small errors in the measurements are manifested aurally as low level noise or distortion.
[28] However, "if the quantisation is performed using the right dither, then the only consequence of the digitisation is effectively the addition of a white, uncorrelated, benign, random noise floor.
The quantization noise level is directly determined by this number, decreasing exponentially (linearly in dB units) as the resolution increases.
The Redbook CD standard uses 16 bits, which keeps the quantization noise 96 dB below maximum amplitude, far below a discernible level with almost any source material.
[29] The addition of effective dither means that, "in practical terms, the resolution is limited by our ability to resolve sounds in noise.
Natural dithering processes, like random thermal movements of molecules, the nonzero size of the reading instrument, and other averaging effects, make the practical limit larger than that of the smallest molecular structural feature.
When discussing their results, the authors commented that: So far, actual jitter in consumer products seems to be too small to be detected at least for reproduction of music signals.
According to their observation, headphones seem to be more preferable to produce sufficient sound pressure at the ear drums with smaller distortions than loudspeakers.
All analog equalizers exhibit this behavior, with the amount of phase shift differing in some pattern, and centered around the band that is being adjusted.
[32] Because the variables involved can be precisely specified in the calculations, digital filters can be made to objectively perform better than analog components.
On the other hand, other engineers also feel that the modeling is still inferior to the genuine outboard components and still prefer to mix "outside the box".
[37] For this reason, recording techniques developed for analog disc, e.g., microphone placement, needed to be adapted to suit the new digital format.
In the popular Hi-Fi press, it had been suggested that linear PCM "creates [a] stress reaction in people", and that DSD "is the only digital recording system that does not [...] have these effects".
[41] Diamond had previously used a similar technique to demonstrate that rock music (as opposed to classical) was bad for your health due to the presence of the "stopped anapestic beat".
[43][44][45] However, a double-blind subjective test between high resolution linear PCM (DVD-Audio) and DSD did not reveal a statistically significant difference.
Dub producer Adrian Sherwood has similar feelings about the analog cassette tape, which he prefers because of its "warmer" sound.
He also pioneered the unsuccessful Digital Compact Cassette and conducted the first recording ever to be commercially released on CD: Richard Strauss's Eine Alpensinfonie.
[52] While vinyl records and common compact cassettes are analog media and use quasi-linear physical encoding methods (e.g. spiral groove depth, tape magnetic field strength) without noticeable quantization or aliasing, there are analog non-linear systems that exhibit effects similar to those encountered on digital ones, such as aliasing and "hard" dynamic floors (e.g. frequency-modulated hi-fi audio on videotapes, PWM encoded signals).
