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8. Re: artifact in spectrogram created using Raven

Subject: 8. Re: artifact in spectrogram created using Raven
From: "Raimund" animalsounds
Date: Wed Jul 18, 2012 10:27 am ((PDT))
> Is there any setting that you can do on a PMD-680 that cuts
> everything over 6k and creates clearly audible reverb and echo??

Hi Klas,

The recorder was set to the MP3 file format at a bit rate of 32 kBit/s, whi=
ch causes that 6 kHz low pass effect and the strange "audible reverb". This=
 effect is very similar to a poorly adjusted FFT-based noise reduction filt=
er, where random sound bits occasionally pop up out of the noise-reduced ba=
ckground noise floor.

As Dan already pointed out, these effects can also be experienced on your m=
obile phone or on SKYPE. Just this morning I have been called by someone th=
rough SKYPE and I did understand next to nothing due to the low bit rate...

Regards,
Raimund


>
>
> At 18:11 2012-07-18, you wrote:
> >--- In  Klas Strandberg <telinga@> wrot=
e:
> > >
> > > Sorry, but I have to straighten this thread out for myself:
> > >
> > > Gabriel says: Even though people have said these are bad recordings,
> > > and I said you will run into trouble in peer review later for
> > using MP3.......
> > >
> > > Are you saying that Lauras files sound the way they do because it's M=
P3??
> >
> >Well, I guess at least three issues emerged in the same thread.
> >
> >1) What is the cause of the artifacts in Laura's recording? My
> >impression was that some knowledgeable people thought it could be
> >low bit rate MP3 alone. Others have put forward different
> >explanations. Of course it will be impossible to say for sure on the
> >basis of the sound file alone. This requires testing the equipment
> >with different settings, and comparing it to reference equipment.
> >
> >2) I said, perhaps a bit harshly, that MP3 should not be used for
> >scientific recordings (also not if it is not the cause of Laura's
> >problem). This was perhaps too strict, as Dan correctly pointed out,
> >but in general MP3 is a bad choice. Science is expensive in terms of
> >money and time. People will be grateful later if you spend a bit of
> >money on an extra memory card, and used PCM/flac for recording.
> >
> >3) For nonscientific purposes, what bit rates are acceptable for
> >good quality? It is not surprising that the opinions on this vary :-)
> >
> >Best, Gabriel
> >
> >
> >
> >
> >------------------------------------
> >
> >"While a picture is worth a thousand words, a
> >sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause=
.
> >
> >Yahoo! Groups Links
> >
> >
> >
> Telinga Microphones, Botarbo,
> S-748 96 Tobo, Sweden.
> Phone & fax int + 295 310 01
> email: 
> website: www.telinga.com
>
>
>








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