> The files are 16 bit, I hope that's not what you're recording at for the =
originals.=A0 Using 24 bit is soo much better for things that are quiet.
James,
Where are you so quiet that you can hear digital noise at -96dB? OK, a
digitiser adds 2 bits of "random" noise to cover the digital steps but that=
is still -84 dB. Wish I had locations and mics which could produce that, bu=
t
in my woods I'm very happy with about -60 ambient noise below peak which
isn't often except in a flat calm. Recording at -16 peak, that's still -68=
noise level and well swamped.
The other factor is that an affordable digitiser is nowhere near that good=
in linearity. Next time I find a very quiet background, I'll do the check,=
but I would expect other factors cause the benefit rather than just bit
steps.
> At low sampling rates like 44.1kHz which maxes out at a theoretical 22,05=
0 Hz you miss out on a lot of the soundscape.=A0
I can't hear much above 13KHz at my advanced age, but I do check at half
speed. The Nyquist "mirror" frequency is 22.05KHz, but that means a
digitiser has to start cutting off at 18 or 19KHz. Listening to 44.1
recordings at half or quarter speed does show a difference to a higher rate=
,
but rarely affecting a bird or insect call over normal background noise in=
my experience. It may affect the noise, but the call?
By the time a recording comes out of a loudspeaker it has suffered a series=
of frequency embarrassments and, for most of us, we would not be able to
describe any digital noise, let alone say whether the recording was at 16 o=
r
24 bits, or 44.1 or 96 rates without an A-B direct comparison. This is the=
difference between hi-fi and reality. :-)
I record long runs and thus amass big files. It is simply more convenient t=
o
keep file sizes smaller and, only if I could identify specific digitising
noise and effects over natural noise, would I contemplate more bits or
faster sampling. It's called pragmatism. :-) Especially when played via
Soundcloud.
> Most mics are tested for 20Hz to 20kHz (assumed averages of human hearing=
), but they pick up sounds a lot higher than 20kHz.
Here lies the rub. Using affordable gear, I don't want harmonics messing up=
my recordings on affordable recorders and playback machines, so I am happie=
r
with a 19KHz or so cutoff. This sharp cutoff does produce ultrasonic ringin=
g
but in practice I've not been able to identify this anomaly.
The big question - is a recording better at 44.1 or 96? It may sound
different, but which sounds better - filtered or unfiltered?
Also it is not generally realised that the HF response of even expensive
mics, even out of a windshield, is very ragged. Published frequency respons=
e
curves are averaged out using a warble tone. Gunmics are even more ragged,=
and so are the various stereo rigs we use. No names, no packdrill, but try=
testing them with a "random noise" source like compressed air and watch the=
peaks as you move the rig. With such unpromising HF responses, what is
hi-fi?
In a sound treated studio with pro standard digitisers plus bigger money,
wide bit sizes and high sapling rates are called for especially if you want=
to impress the clients, but in the wild, nature does not give us the clean=
sound we would like. I usually use a bass roll-off and have been known to d=
o
some gentle HF noise reduction, but only in order to present an equivalent=
sound to that filtered and interpreted by my ears and brain. Sound recordin=
g
is a highly artificial process.
Incidentally I have constructed an "anti-bass rolloff" correction on
Audacity if I ever want the full bass back. At those frequencies and levels=
,
nothing is lost audibly by the matching filters except the risk of bass
overload which sounds horrible.
David Brinicombe
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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