Hi Phil and Patrick,
yes, it is indeed very simple to make this kind of conversion. I used the
(expensive) Avisoft-SASLab Pro software
(http://www.avisoft.com/soundanalysis.htm) for this, but it can also be made
with any other sound editing software such as Audacity. On Audacity, the
corresponding command is titled "Set Rate" > "Other...", which can be found on
the pop-up menu that appears when you click at the tiny black arrow on the left
of the track representation.
I just investigated the frequency response of the PCM D-50 microphones a bit
further. They seem to be quite sensitive up to about 30 kHz. That's the reason
why they worked so good for the relatively low-frequency echolocation calls of
the Noctule bat. They still work beyond 30 kHz, but the sensitivity drops
significantly at those frequencies. So, the results would not be as good when
recording other bat species such the Pipistrelle for instance.
Regards,
Raimund
--- In ". m u r m e r ." <> wrote:
>
> Raimund Specht wrote:
> > 2. Modifying the sample rate attribute in the file header from 96 kHz to
> > 5.5 kHz, which stretches the time scale by a factor of 17.45 = 96 kHz / 5.5
> > kHz. As a result, the ultrasonic bat calls move down into our hearing range.
>
>
> forgive me if this is a foolish question, but how do you directly modify
> the sample rate attribute in a soundfile header? do you need a
> particular piece of software? this seems like a spookily simple way to
> do a basic time-stretch, quite enticing...
>
> best,
> patrick
>
> --
--- In Philip Tyler <> wrote:
>
> Hi Raimund
>
> Many thanks for the info. I understand everything except the "Modifying the
> sample rate attribute in the file header"?
>
> What do you use to do that, if I may ask?
>
> Regards
>
> Phil
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