A few days ago, I was sent this very interesting article on being tired of the Obfuscation on Digital Audio:
http://people.xiph.org/~xiphmont/demo/neil-young.html
All this info can be found on MIT's open courseware. It'll take awhile to digest, so here's a few quotes to whet your appetite.
On Golden Ears:
- Auditory researchers would love to find, test, and document individuals with truly exceptional hearing, such as a greatly extended hearing range. Normal people are nice and all, but everyone wants to find a genetic freak for a really juicy paper. We haven't found any such people in the past 100 years of testing, so they probably don't exist.
- Unfortunately, there is no point to distributing music in 24-bit/192kHz format. Its playback fidelity is slightly inferior to 16/44.1 or 16/48, and it takes up 6 times the space.
- Responses indicate that few people understand basic signal theory or the sampling theorem, which is hardly surprising. Misunderstandings of the mathematics, technology, and physiology arose in most of the conversations,
often asserted by professionals who otherwise possessed significant audio expertise.
Argument for limiting bandwidth to the audible spectrum (rather than up to 196 KHz)
- Neither audio transducers nor power amplifiers are free of distortion, and distortion tends to increase rapidly at the lowest and highest frequencies. If the same transducer reproduces ultrasonics along with audible content, any nonlinearity will shift some of the ultrasonic content down into the audible range as an uncontrolled spray of intermodulation distortion products covering the entire audible spectrum.
- You can't and won't have ultrasonic intermodulation distortion in the audible band if there's no ultrasonic content (like on CDs)---- Just love this one..
Intermodulation test for your system that you can try yourself is provided
- If you hear anything, your system has a nonlinearity causing audible intermodulation of the ultrasonics.
- there are (and always will be) reasons to use more than 16 bits in recording and production. None of that is relevant to playback; here 24 bit audio is as useless as 192kHz sampling. The good news is that at least 24 bit depth doesn't harm fidelity. It just doesn't help, and also wastes space ....16 bits is enough to store all we can hear, and will be enough forever .............. a 16-bit noise floor is already below what we can hear ......... Professionals use 24 bit samples in recording and production [14] for headroom, noise floor, and convenience reasons........24 bits keeps the accumulated noise at a very low level. Once the music is ready to distribute, there's no reason to keep more than 16 bits.
- Empirical evidence from listening tests backs up the assertion that 44.1kHz/16 bit provides highest-possible fidelity playback. There are numerous controlled tests confirming this, but I'll plug a recent paper, Audibility of a CD-Standard A/D/A Loop Inserted into High-Resolution Audio Playback, done by local folks here at the Boston Audio Society...............This paper presented listeners with a choice between high-rate DVD-A/SACD content, chosen by high-definition audio advocates to show off high-def's superiority, and that same content resampled on the spot down to 16-bit / 44.1kHz Compact Disc rate. The listeners were challenged to identify any difference whatsoever between the two using an ABX methodology. BAS conducted the test using high-end professional equipment in noise-isolated studio listening environments with both amateur and trained professional listeners. In 554 trials, listeners chose correctly 49.8% of the time. In other words, they were guessing. Not one listener throughout the entire test was able to identify which was 16/44.1 and which was high rate.
- The BAS test I linked earlier mentions as an aside that the SACD version of a recording can sound substantially better than the CD release. It's not because of increased sample rate or depth but because the SACD used a higher-quality master. When bounced to a CD-R, the SACD version still sounds as good as the original SACD and better than the CD release because the original audio used to make the SACD was better. Good production and mastering obviously contribute to the final quality of the music
For a video presentation and some graphic demonstrations of sampling, quantization, bit-depth and dither on real audio equipment using both modern digital analysis and vintage analog bench equipment, see:
http://xiph.org/video/vid2.shtml
http://people.xiph.org/~xiphmont/demo/neil-young.html
All this info can be found on MIT's open courseware. It'll take awhile to digest, so here's a few quotes to whet your appetite.
On Golden Ears:
- Auditory researchers would love to find, test, and document individuals with truly exceptional hearing, such as a greatly extended hearing range. Normal people are nice and all, but everyone wants to find a genetic freak for a really juicy paper. We haven't found any such people in the past 100 years of testing, so they probably don't exist.
- Unfortunately, there is no point to distributing music in 24-bit/192kHz format. Its playback fidelity is slightly inferior to 16/44.1 or 16/48, and it takes up 6 times the space.
- Responses indicate that few people understand basic signal theory or the sampling theorem, which is hardly surprising. Misunderstandings of the mathematics, technology, and physiology arose in most of the conversations,
often asserted by professionals who otherwise possessed significant audio expertise.
Argument for limiting bandwidth to the audible spectrum (rather than up to 196 KHz)
- Neither audio transducers nor power amplifiers are free of distortion, and distortion tends to increase rapidly at the lowest and highest frequencies. If the same transducer reproduces ultrasonics along with audible content, any nonlinearity will shift some of the ultrasonic content down into the audible range as an uncontrolled spray of intermodulation distortion products covering the entire audible spectrum.
- You can't and won't have ultrasonic intermodulation distortion in the audible band if there's no ultrasonic content (like on CDs)---- Just love this one..
Intermodulation test for your system that you can try yourself is provided
- If you hear anything, your system has a nonlinearity causing audible intermodulation of the ultrasonics.
- there are (and always will be) reasons to use more than 16 bits in recording and production. None of that is relevant to playback; here 24 bit audio is as useless as 192kHz sampling. The good news is that at least 24 bit depth doesn't harm fidelity. It just doesn't help, and also wastes space ....16 bits is enough to store all we can hear, and will be enough forever .............. a 16-bit noise floor is already below what we can hear ......... Professionals use 24 bit samples in recording and production [14] for headroom, noise floor, and convenience reasons........24 bits keeps the accumulated noise at a very low level. Once the music is ready to distribute, there's no reason to keep more than 16 bits.
- Empirical evidence from listening tests backs up the assertion that 44.1kHz/16 bit provides highest-possible fidelity playback. There are numerous controlled tests confirming this, but I'll plug a recent paper, Audibility of a CD-Standard A/D/A Loop Inserted into High-Resolution Audio Playback, done by local folks here at the Boston Audio Society...............This paper presented listeners with a choice between high-rate DVD-A/SACD content, chosen by high-definition audio advocates to show off high-def's superiority, and that same content resampled on the spot down to 16-bit / 44.1kHz Compact Disc rate. The listeners were challenged to identify any difference whatsoever between the two using an ABX methodology. BAS conducted the test using high-end professional equipment in noise-isolated studio listening environments with both amateur and trained professional listeners. In 554 trials, listeners chose correctly 49.8% of the time. In other words, they were guessing. Not one listener throughout the entire test was able to identify which was 16/44.1 and which was high rate.
- The BAS test I linked earlier mentions as an aside that the SACD version of a recording can sound substantially better than the CD release. It's not because of increased sample rate or depth but because the SACD used a higher-quality master. When bounced to a CD-R, the SACD version still sounds as good as the original SACD and better than the CD release because the original audio used to make the SACD was better. Good production and mastering obviously contribute to the final quality of the music
For a video presentation and some graphic demonstrations of sampling, quantization, bit-depth and dither on real audio equipment using both modern digital analysis and vintage analog bench equipment, see:
http://xiph.org/video/vid2.shtml
