Laura,
Never having heard one before, I checked out the call of Nelson's
Sparrow on xeno-canto, there is an excellent recording there by
Andrew Spencer, with this link:
http://www.xeno-canto.org/55204
I now understand that the species has a really weird hissing type of
call, not like anything I've heard before.
I made two sonograms, comparing Andrew's recording and your
recording, just selecting one call. These sonograms are in the
Photos section of this group. (no room in the files section!) Find
it under N for 'Nelsons Sparrow'.
Andrew's recording was submitted to xeno-canto in mp3 format, but it
shows a much higher range of sounds in kHz, than does your
recording. You can see that Andrew's bird makes that buzzing/
hissing sound up to maybe 8 kHz, with additional natural harmonics
above that.
Laura's sound only goes up to 6.5 kHz.
Laura, it depends on what you are needing to measure, whether or not
your recordings will have any scientific use, e.g. if you were only
measuring how often they called that would be ok, but if you want to
analyze the actual call, you cannot because it is incomplete.
Vicki Powys
Australia
On 17/07/2012, at 10:13 AM, Klas Strandberg wrote:
> Laura, I have listened to
> http://soundcloud.com/laura-hilberg/6-12-12-bhm-nesp-11 and something
> digital must be seriously and totally wrong with your set up or
> digital chain.
>
> No microphone or other analog unit sounds like that and certainly not
> a Telinga connected to a PMD recorder. Even handling noise and noise
> from the dish sounds just ridiculous. Every normal mp3 file sounds
> MUCH better than that, so I can't hear that that would be the cause
> either.
>
> I made a comment at 0,46 that I hear a limiter or automatic gain
> control in action, and the same bumping can be heard at several
> locations, but I don't think it is a limiter, but something worse.
>
> If you can, please get the same set up working again with the same
> settings and just talk into the microphone as if it was a common
> interview. Best is if you remove the dish. Make a few minutes at
> Soundcloud the same way as before.
>
> Klas
>
> At 01:07 2012-07-17, you wrote:
>> Hi Laura,
>>
>> I downloaded both your files from SoundCloud. Listening to the
>> longer file I would say that the quality is appalling and unuseable
>> for any research purposes. I am surprised you were sent out to do
>> field work without either having someone set the recorder correctly
>> for you, or showing you what you needed to do. You should have been
>> monitoring the sounds you were recording through headphones, then you
>> would have known something was wrong right from the beginning.
>>
>> In analyzing what has gone wrong, I see that the audio frequency in
>> both files only goes as high as 6.6 kHz, while the birdsong is
>> starting at around 4 kHz and would have included sounds higher than
>> 6.6 kHz. Hence, apart from any overload problems, much of the
>> birdsong is simply not in the recording.
>>
>> Such a low sample rate would be caused by using either a very low
>> quality setting in the mp3 format and/or and sample rate of less than
>> 16 (should be 44.1 or more).
>>
>> When you are looking at a sonogram of properly recorded birdsong, you
>> should be seeing a window that shows sounds up to 22 kHz.
>>
>> Vicki Powys
>> Australia
>>
>>
>>
>>
>>
>>
>>
>>
>> On 17/07/2012, at 7:18 AM, laura.hilberg wrote:
>>
>>> Thank you all so much for your suggestions (and experiments)! It's
>>> a huge relief 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/nesp-song-short-clip. I made it public and
>>> downloadable, so hopefully it will work for everyone. I also
>>> uploaded the complete, unmodified sound file (about 10 minutes),
>>> which is at http://soundcloud.com/laura-hilberg/6-12-12-bhm-nesp-11.
>>>
>>> To try to answer some of your questions:
>>>
>>> 1) I am absolutely sure that the automatic gain was turned off.
>>> What this meant was that I adjusted it manually for each recording,
>>> trying to ensure that the gain was high enough to pick up the sound
>>> but not so high that it went 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 not sure what exactly that is. John, your experiment
>>> with the fan sounds exactly like what I am experiencing, with the
>>> white shadow eclipsing the background noises in high-volume (or
>>> perhaps it is related to high frequency) sounds.
>>>
>>> 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 changes what I see. I know the low-pass filter
>>> was turned off on the recorder, so 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 embarrassed to say that it's a problem I'm stuck
>>> with, as that was the default file format, no one mentioned that it
>>> wouldn't be good enough, and I didn't know enough to change it.
>>>
>>> Laura
>>>
>>
>>
>>
>> ------------------------------------
>>
>> "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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