I wanted to put my two cents into the 24-bit discussion.
I think you are missing the real advantages of 24-bit over 16-bit for
recording soundscapes. I see it as an advantage to record at lower levels
than I would have using a 16-bit system. When recording nature sounds there
is always the unexpected sound that is louder than we would expect. To make
best use of a 16-bit system, you would have to play with gain controls to
achieve a signal of less than 0dB, but as close as you can to 0dB with out
going over. You can be just happy with a setting, recording at -10 to -20db
average, giving you around a 75dB dynamic range. Then a bird, a thunder
clap, or other sound suddenly comes and clips the recording sequence, many
times ruining the entire recording. Sometimes just a turn in the sound
maker's body can clip the signal. With a 24-bit system, you can comfortably
record at signal levels of -30 to -40dB average, while still getting over
80dB of dynamic range. At those levels you are unlikely to have an inherent
sound go into clipping, and gives you the added advantage of getting rare
sounds when say an owl perches over your mic set-up. Post editing can bring
the signals up to the level you want. I see 24-bit systems as an advantage
to the recordist to use the added dynamic range, not necessarily as being
better sound quality. With my 24-bit system, I set the gain to 30, 40, or
50dB and walk away. No fussing around anymore, watching meters. I have
colored LED meters I can watch through binoculars from a long distance away,
just to make sure everything is cool. I will say that I found out how easily
a signal can saturate, and how many mini-disc type level meters are too slow
to know the event occurred. Any saturating, no mater how brief will cause a
loss in quality, and that alone maybe the advantage of sound quality in a
24-bit system. While out recording this Spring I can't tell you how many
times my recordings would have been ruined by some birds that came in close
to my recording set-up if I was still using a 16-bit system and flirting
with saturation. Instead, those recordings came out perfect. Very few 24-bit
recorders can achieve true 24-bit performance. The only ones that I know of
are from Core Sound and Sound Devices, but their specifications are more
based on part specification than actual measurements from completed units,
but they seem to work ok. The one problem is that those recorders have
higher noise levels at low gain settings, making the whole advantage
somewhat pointless. All those other "24-bit" recorders from Zoom, M-Audio,
Fostex, and others should be thought of as 16-bit recorders and no more. The
advantage of the M-Audio is that it at least has a 24-bit input to bypass
their poor inputs. I still use 16-bit recorders for capturing singles, as I
can adjust gain on the fly to get the best results as I follow the subject
around.
Bruce Rutkoski
www.natureguystudio.com
Re: 24 bit vs. 16 bit
Posted by: "Rob Danielson" danielson_rob
Sat Jul 21, 2007 9:06 am (PST)
Hi--
I'll risk picking up this topic again to point to the quiet location
comparison test I promised:
http://www.uwm.edu/~type/audio-reports/LowSaturation/LowFieldSaturation2.htm
l
It seems to confirm what Raimund, Walt and others were saying that it
is highly unlikely to encounter quantizing noise when typical mic pre
levels and mics are used with 16 bit field recording.
Rob D.
= = = =
At 3:30 PM +0000 5/15/07, Raimund Specht wrote:
>Hi Rob,
>
>In my experience, there is still no real advantage for recording at
>24 bit in the field. The SoundDevices example is not surprising to
>me. If one records in 16 bit at an extremely low level of -40 dBFS,
>the quantization noise will of course become audible after
>normalization. To me, this it not a real-world example that applies
>to nature recording. Yes, it is true that the SD preamplifiers and
>A/D converters can provide a dymnanic range that exceeds 16 bits
>(which is indeed not the case for all 24 bit recorders). But that
>large dynamic range is simply not required in the field...
>
>Regards,
>Raimund
>
>
>--- In Rob Danielson <>
>wrote:
>>
>> At 7:24 AM +0000 5/15/07, Raimund Specht wrote:
>> >But that would probably open another can of worms, which could
>> >further damage a few more illusions on the latest developments in
>> >audio technology. So, I should better shut up
>> >for now ;-)
>> >
>> >Raimund
>>
>> Hi Raimund--
>>
>> I see more consistency than disagreement.
>>
>> I believe there is pretty strong consensus that audible quality
>> differences between fully saturated 16 and 24 bit sound files are
>> minimal. It seems to me that your discussions of 8 bit recording
>and mp3 encoding are examples of the advantages of of robust file
>> saturation as well.
>>
>> There are recordists on the list, a good percentage of whom record
>in sparser, northern environments who routinely bring home much
>> "thinner" recordings with more air and ambience than recordings
>made nearer the tropics. More and more of these recordists have been
>> observing the reduced noise advantage of recording quiet locations
>at 24 bits and experiencing more efficient filtering and other digital
>> processing in post. The Sound Devices comparison appears to provide
>> strong evidence in support of the first of these observations. As
>> yet, I've not read a challenge to the low saturation observation
>that takes SD's 16 bit and 24 bit -40dB examples into consideration, so
>> there's a good chance we have consensus on this point as well. :-)
> > Rob D.
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