Thank you all so much for your suggestions (and experiments)! It's a huge r=
elief to have a community of people who really understand this stuff.
I uploaded a short recording of a single song (the same one in the picture)=
. It is on SoundCloud, and the URL is http://soundcloud.com/laura-hilberg/n=
esp-song-short-clip. I made it public and downloadable, so hopefully it wil=
l work for everyone. I also uploaded the complete, unmodified sound file (a=
bout 10 minutes), which is at http://soundcloud.com/laura-hilberg/6-12-12-b=
hm-nesp-11.
To try to answer some of your questions:
1) I am absolutely sure that the automatic gain was turned off. What this m=
eant was that I adjusted it manually for each recording, trying to ensure t=
hat the gain was high enough to pick up the sound but not so high that it w=
ent over. I'm not sure if this is the same thing as 'fixed gain', but I do =
know that it was adjusted manually only.
2) The limiter was turned off.
3) Is clipping the same thing as aliasing (referred to in the Raven manual)=
? If so, then I know what you're referring to, but if not then I'm still no=
t sure what exactly that is. John, your experiment with the fan sounds exac=
tly like what I am experiencing, with the white shadow eclipsing the backgr=
ound noises in high-volume (or perhaps it is related to high frequency) sou=
nds.
If it has to do with aliasing (as I understand it, sounds that are over the=
Nyquist frequency are distorted upside down somehow), then Raven has a low=
-pass (anti-aliasing) filter. I'll experiment with that and see if it chang=
es what I see. I know the low-pass filter was turned off on the recorder, s=
o perhaps this is the problem.
4) My files were recorded as MP3s, with a 44.1kHz sampling frequency and 16=
-bit sampling rate. Perhaps this is the problem... if so, then I am embarra=
ssed to say that it's a problem I'm stuck with, as that was the default fil=
e format, no one mentioned that it wouldn't be good enough, and I didn't kn=
ow enough to change it.
Laura
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