ralphpnj wrote: > > > An orchestra is recorded while playing a symphony and the dynamic range > of the performance is a maximum of 65 db above the noise floor - so if > the noise floor is at 30db then the maximum dynamic range required to > record the performance without distortion at the peak volume would be 95 > db (30db + 65 db). >
IME close to being a real world example. Most adult audiences are comfortable when the louder passages (but no necessarily the peaks) run in the 90-95 dB range. 30 dB is a very quiet concert room, but put an audience into it, and just their breathing and body noises will add another 10-25 dB. If the room is empty, its the middle of the night in a quiet part of town, the HVAC is turned off, and the streets are free of traffic and the air is free of aid traffic, lower numbers such as 20 dB might be logged. OTOH, your living room is probably running more like 40 dB at most times. > > The maximum dynamic range of a 16 bit file is 96 db and that of 24 bit > is 144 db. > With dither, maybe 1-3 poorer than that. The recording gear adds appreciable noise of its own. The best recording mics have equivalent noise of just a few dB, but a typical recording mic will have equivalent noise on the order of 18 dB. If minimal micing is used, there are only from 2 to 6 mics active, but that will raise the noise level by from 3 to 5 dB. If multiple micing is used then the background noise due to the mics increases by 3 dB times the logarithm base 2 of the number of mics at best. IOW add 3 dB for the second mic, 6 dB if there are 4 mics, 9 dB if there are 8 mics, etc. For low frequency noises that are in phase for all the mics, the backgound noise adds linearly as the number of mics increase. IOW, YMMV. > > So how does placing the above symphony recording into a 24 bit file > versus a 16 bit file increase the dynamic range of the recording? > If the recording engineer uses a dynamic range expander or rides the gain, then a recording's dynamic range can exceed that of the live performance. > > Okay so I realize that putting the above symphony recording into a 24 > bit file does not actually increase the inherent dynamic range of the > recording and this the point I'm trying to make. To put it another way, > I don't believe that any listening tests, either double blind or > sighted, are even need to determine if this is true since it is just a > purely mathematical function - increasing the bit depth of a digital > audio recording cannot and does not increase the dynamic range of the > music contained in the digital audio file. I like to think of the whole > thing using an envelope analogy - the recording of the performance would > be a letter on an 8 1/2" X 11" piece of paper with the 16 bit file being > a 9" X 12" envelope and the 24 bit file being an 11" X 14" envelope - > the letter nicely fits into both envelopes however the size of the > letter remains the same. > > Am I missing something or is the whole 16 bit versus 24 bit for a fully > edited and mixed recording just another completely false marketing > claim? It is very rare case where doing a good job of converting a 24 bit recording to 16 bits makes an audible difference. This article http://www.avsforum.com/forum/91-audio-theory-setup-chat/2370801-test-your-ability-hear-high-res-audio.html shows tests you can do yourself to verify this: ------------------------------------------------------------------------ arnyk's Profile: http://forums.slimdevices.com/member.php?userid=64365 View this thread: http://forums.slimdevices.com/showthread.php?t=105717 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
