naturerecordists
[Top] [All Lists]

5. Re: artifact in spectrogram created using Raven

Subject: 5. Re: artifact in spectrogram created using Raven
From: "Raimund" animalsounds
Date: Wed Jul 18, 2012 9:03 am ((PDT))
Hi Laura,

As the previous discussion showed, it is not always straightforward to full=
y understand the equipment-related issues - even for the experienced expert=
s. So, there is no reason to worry about the lack of (initial) experience..=
.

<<I will be analyzing simple parameters such as length, high and low freque=
ncy (well, maybe not high frequency anymore), rate of delivery, etc. No wor=
k like this has been done before; the only study looking at their song foun=
d a slower rate (due to longer gaps between songs).

I am encouraged to hear that you feel like I can examine frequencies below =
6khz safely - I believe that as well. If you have any thoughts about what a=
spects of the song I could and could not safely measure, that might give me=
 some ideas that I haven't already thought of.>>

Yes, I agree that you could safely measure at least a number of temporal pa=
rameters (rate of delivery, total duration of the song, the time interval f=
rom the beginning of the song to the pronounced 2.8 kHz element close to th=
e end) and a few frequency parameters (the exact (mean) frequency of that 2=
.8 kHz element and maybe the minimum frequency of the harsh section at the =
beginning).

Theoretically, one could also try to measure the mean spectrum of first har=
sh part of the song (peak frequency, bandwidth, quartiles and wiener entrop=
y), but these parameters would probably be too much affected by the specifi=
c recording conditions (the frequency response of a parabolic microphone is=
 not perfect and depends on how it is aimed relative to the singing bird).=


Bye the way, I would guess that the mp3 compression (exept of course the li=
mitation set by the 6 kHz low-pass filter effect) has no signifinat effect =
on the frequency parameters.

There is also a gentle amplitude modulation during the first 200 ms of the =
song. In the recording that you posted I can count three amplitude peaks (t=
hese become more evident on the waveform after high-pass filtering). Maybe =
this is something that differs between dialects.

Best wishes and good luck with your study,
Raimund







<Prev in Thread] Current Thread [Next in Thread>
Admin

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU