Anyone used dodotronic microphone? (1 Viewer)

I've bought one and wondered if anyone has had a go with one?


http://www.dodotronic.com/zoologia/files/Ultramic_User_Guide.pdf

First results....

Jane,

If you look at the bottom of the hook of your bat echolocation call you may note that it is about 43 kHz. If the bat is nearby the spectrogram will show a second harmonic at 86kHz, and in principle a third at 129kHz. Now the sampling in your spectrum seems to be 192KHz this a maximum sound frequency is 96kHz. You microphone is sensitive to 200KHz, which means that your 129KHz is now 32kHz above your sampling frequency, thus you will see it showing a max frequency at 96-32kHz or 64kHz and inverted in shape, and that's what you have. This is what you get if the mic sensitivity goes beyond the frequency limit set by the sampling frequency. Nice example of aliasing. Not also that your second harmonic right at the top of your 96kHz range may have a small relfetive hook at the start of the call.

Hard to tell from one sound but the frequency, the length and the shape fit a pipistelle bat (Pip pip).

Harry

It sounded like a common Pip on heterodyne - the second animal was aNoctule

Is this a Myotis?

and what was this.....apart from loud?

I'm starting to feel my way into using this kit - so will post results here....

1st the Common pipistrelle - my 1st capture

Sound files captured with audacity. I've used noise reduction on the original file then used ravenlight - a free sonagram analyser to view thew results.

and the Noctule from the 1st night. I'm getting the calls a lot longer that literature - I don't know if that is a mistake in measuring, an effect eg echo or a property of the microphone

Jane,

It appears that you have identified correctly the noctules (and the pipistrelles). The length of the sounds in the post of 07:32 are about 20 ms, which is fine for noctule. The rest is pure echo. The interval (start to start) of the two echolocation sounds is about 230ms, which fits within the range of notcule (Nyctalus noctula).

In your post of 06:49 note that the "upward hook" is caused by aliasing, and in that sense is a reflection from the 3rd hamonic from the higher frequencies - the mic effect mentioned in my earlier post. The lowest frequency and the 9ms length are fine but the highest frequency of the fundamental spectral signature is not well determined as it is confused with the above mentioned alias. I cannot be sure but I feel that the highest frequency of the fundamental is between 46 and 54 kHz. Fits Pip pip.

In your post of 07:27 the loud forest of peaks could be two pipistrelles (Pip pip) having fun or querreling. You have a key feature in these spectrograms for iding. That are the two sets of social calls, the first set is at 30KHz close to the beginning and the second close to the end at 20kHz. Look for these kind of things and make a spectrum with a shorter fft to wiew the structure of these more clearly. They are reasonably good looking for a pipistrelle, but due to limited resolution I cannot be sure.

Most myotis calls go from high frequencies usually down to the 20-30 KHz range.

Echolocations are nice but the social calls are the gems. Good job.

Harry J

Thanks Harry.

I've discovered that I have been recording at a lower sampling rate than I was viewing - so have lost some detail - and perhaps made some artefacts.

I'll make more "spread" spectrograms of the conversation and post them.

The file is too big for me to handle it easily - but I have managed some better time resolution spectrograms. If this isn't enough I'll cut a few seconds out of the 40 minute file and work on that. It looks like the 20kHz close to the end of the spectrogram above is a distant noctule - its get louder a few milliseconds later!

This help is greatly appreciated because I am new to the technology and naive about Bats!

So here is 7 seconds cut out of the 40 min file - so so much easier to handle. I've used noise reduction.

I also have a Noctule interaction recorded

Last night I witnessed some interesting inter-specific interaction. There was a Noctule present for about 40mins, and a Pipistrelle visiting occasionally. I knew when the Pip was coming because the Noctule have a very distinctive and load call which sounded like a threat!