Peter,
All your questions about the frogs are interesting ones and of course
I don't know the answers. Except to say I think it is just one frog
giving the calls.
In my experience of living for 15 years in an area where there are
quite a few GT Frogs about, I had never heard this call before until
a couple of years ago, and it was a very long time before I was able
to get a recording. The call would occur briefly about once each
night during the summer. I kept microphones on my front verandah
because I was also doing some research on night birds. That way I
was eventually able to pick up a recording and much later tracked it
down to Green Tree Frog distress call.
At one stage a small goanna got into my ceiling and ate some frogs,
but the frogs then gave a different sort of distress call, more of a
moaning shriek. I have picked up the frogs with my hands and they
make no sound at all, or maybe just a brief croak. It was only with
the mice attacking them that the frogs gave this shrill call. I
don't know why the frogs didn't simply hop away. I suppose the mice
just chased them and nipped at their feet until they could not hop
any more.
I have also heard GT Frogs occasionally give a sharp yapping call.
Mostly of course they just give a loud and rhythmic croak-croak-croak
call, especially when it is hot and raining.
Vicki
On 05/12/2011, at 8:52 AM, Peter Shute wrote:
> OK, good, I hadn't noticed that parameter before, and it makes
> quite a difference. I do see the faint bands now. I'll sent Tom
> Tarrant the link to your sonogram, and he can decide for himself.
>
> Now I'm curious to know what was happening to the frog. And was it
> one frog, or a series of frogs being attacked by something one by
> one? I'm also curious to know why this call is apparently uncommon
> on Tom's recordings - I would have thought froggy death was a daily
> occurrence in that habitat. Perhaps it's normally too swift. (I'm
> not expecting any answers to these questions.)
>
> Peter Shute
>
> ________________________________
> From:
> On Behalf Of vickipowys
> Sent: Monday, 5 December 2011 8:12 AM
> To:
> Subject: Re: [Nature Recordists] Re: Advice needed for cleaning up
> this recording
>
>
>
> Peter,
>
> Yep, FFT =3D the sharpness setting in Raven Lite. In some applications
> it is called FFT (Fast Fourier Transform).
>
> Basically when you are adjusting any sonogram settings, you simply
> juggle the available settings until you get an image as clear as
> possible and that suits your needs. A less contrasty sonogram is
> more likely to show up some of the less obvious aspects of the
> sound. A more contrasty sonogram can be useful for publication,
> provided you already have a good clear sound to work with.
>
> I like to work with black and white (which is useful for publication)
> altho some members on this list prefer to work with colour for on
> screen analyses.
>
> For anyone using Izotope, the lovely sonograms that it produces can
> be set to white on black, but not black on white. But it is easy to
> invert the image using photoshop so that you get black on white. You
> need to take a screen shot of the Izotope screen first, to work with.
>
> Vicki
>
> On 05/12/2011, at 5:31 AM, Peter Shute wrote:
>
>> FFT? Where do I set that in Raven Lite? All I see is a third
>> adjustment called "sharpness".
>>
>> Peter Shute
>>
>> ________________________________
>> From: <naturerecordists%
>> 40yahoogroups.com>
>> <naturerecordists%
>> 40yahoogroups.com>] On Behalf Of vickipowys
>> <vickipowys%40skymesh.com.au>]
>> Sent: Sunday, 4 December 2011 2:20 PM
>> To: <naturerecordists%
>> 40yahoogroups.com>
>> Subject: Re: [Nature Recordists] Re: Advice needed for cleaning up
>> this recording
>>
>>
>>
>> Peter,
>>
>> You are quite right to be suspicious of the effects filtering may
>> have on a sonogram. So let's go back to the original.
>>
>> If you look at the left hand channel of the original recording in
>> Raven Lite, with the settings at 50 darkness and 50 contrast, and FFT
>> size 2516, that may help. Expand the sonogram window so that you are
>> seeing about 1 minute of sound, and only up to 10 kHz, then you
>> should be able to see two more harmonic bands at around 3 khz and 2
>> khz for at least some of the calls. At 1 kHz things get messy
>> because of other things calling.
>>
>> In Sonic Visualizer, I could not find where to adjust the brightness
>> and contrast and FFT for the sonograms, and therefore could not get a
>> very clear result.
>>
>> Izotope RX gave a good result (but only very slightly better than
>> Raven Lite), i.e. just looking at the spectrogram window of the
>> original recording and adjusting the controls for clearest settings.
>>
>> You are right that normally it is the higher frequencies that are
>> attenuated by distance. In the case of the frog distress call
>> though, the strongest part of the call is not in the lowest
>> frequencies, but higher up, say above 3 kHz. So with Tom's call
>> being so faint in the first place, maybe the lower frequencies simply
>> did not pick up on the recording.
>>
>> Also, I don't know what other effects the mp3 format may have had on
>> the recording.
>>
>> cheers,
>>
>> Vicki
>>
>> On 04/12/2011, at 12:56 PM, Peter Shute wrote:
>>
>>> Interesting. I can see the same sonogram patterns using Raven and
>>> Sonic Visualiser using the track you just uploaded, but on the
>>> original and all other attempts at cleaning it up, the sub 4kHz
>>> bands aren't really visible. Even in yours, they're much fainter
>>> that those above 4.
>>>
>>> I agree it looks like a good match, and a very likely one too,
>>> given the location, but I'm wary of something that's completely
>>> invisible on the original.
>>>
>>> Sonograms are a new thing to me, so I'm right out of my depth here.
>>> Do you think the distance and reverb can explain why the lower
>>> harmonic bands are fainter? I would have thought higher frequencies
>>> would be attentuated by distance more than lower ones (but I'm not
>>> sure about that).
>>>
>>> Or perhaps they're just almost completely masked by the frog
>>> chorus, and would have to be fainter once that's removed. On closer
>>> inspection, I can see a faint band around 3kHz on the original in
>>> a couple of spots (eg 28s), but I just couldn't say below that.
>>>
>>> Peter Shute
>>>
>>> ________________________________
>>> From: <naturerecordists%
>>> 40yahoogroups.com><naturerecordists%
>>> 40yahoogroups.com>
>>> <naturerecordists%
>>> 40yahoogroups.com><naturerecordists%
>>> 40yahoogroups.com>] On Behalf Of vickipowys
>>> <vickipowys%
>>> 40skymesh.com.au><vickipowys%40skymesh.com.au>]
>>> Sent: Sunday, 4 December 2011 11:25 AM
>>> To: <naturerecordists%
>>> 40yahoogroups.com><naturerecordists%
>>> 40yahoogroups.com>
>>> Subject: Re: [Nature Recordists] Re: Advice needed for cleaning up
>>> this recording
>>>
>>>
>>>
>>> Peter,
>>>
>>> I'm sorry you've given up on the mystery call. Here is one last
>>> attempt on my part to convince you the mystery call really is the
>>> distress call of a Green Tree Frog.
>>>
>>> I've selected just a short side-by-side comparison, using the
>>> clearest part of Tom's recording that I could find. I've also
>>> presented the recordings at half speed, which is always useful for a
>>> listening test.
>>>
>>> This is the soundcloud link:
>>>
>>> http://snd.sc/ticMjy
>>>
>>> I've included a Raven sonogram that shows how the harmonics,
>>> although
>>> faint, do extend well below 4 kHz (you thought they did not).
>>>
>>> I did some broad band noise reduction on Tom's original recording
>>> using RX, and removed the prominent insect call.
>>>
>>> cheers,
>>>
>>> Vicki
>>>
>>> On 03/12/2011, at 7:26 PM, Peter Shute wrote:
>>>
>>>> Thanks everyone for your attempts at cleaning up this recording.
>>>> We've given up on identifying the call for now. I assume it must be
>>>> a lesser known call that we have no samples of for comparison. We
>>>> had quite a few suggestions that sounded similar, but nothing with
>>>> a matching sonogram.
>>>>
>>>> Now I just have to try to understand the steps you all took so I
>>>> can try for myself next time.
>>>>
>>>> Peter Shute
>>>>
>>
>>
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