Difference between revisions of "Spectrograms of the call of the Common Swift"

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(Multiple notes or turbo vibrato)
 
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=The polyphonic call of the Common Swift=
 
=The polyphonic call of the Common Swift=
  
For the last few years, I've looked after fallen Common Swifts
+
The last few years, I've helped fallen Common Swifts grow and fly again, and
and, in some of the 45-minute breaks between feeding, recorded some of their cheerful chirping
+
In some of the 45-minute breaks I had between feeding them, I recorded some of their chirping,
with a high-quality microphone.
+
hoping to learn their language.
  
I was thinking to try and learn to recognise a little of their language
+
Instead I found another marvel: they sing more than one note at a time.
so as to know when someone was thankful, thirsty,
 
hungry, afraid, in pain or whatever, so as to be able to treat them better.
 
 
 
Instead I found another marvel: they can sing more than one note at a time.
 
  
 
==Multiple notes or turbo vibrato==
 
==Multiple notes or turbo vibrato==
  
Here's the third trill of a ten-second sequence of fourteen trills from Rondone #3 of 2018.
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Here's the third of a ten-second sequence of fourteen trills from Rondone #3 of 2018.
  
 
{{Spectrogallery|2018-05 Rondone 2018-05 n3 polyphonic call 0.4s}}
 
{{Spectrogallery|2018-05 Rondone 2018-05 n3 polyphonic call 0.4s}}
  
and here it is slowed down by eight times, which drops it by three octaves so that we can hear it better
+
The bottom of the spectrogram represents 3386Hz, the top 16106Hz and the clip lasts 0.4 seconds.
 +
The yellow line is the main song ranging from 4000 to 4500Hz and the fainter line above is the first harmonic
 +
of that tone, from 8000 to 9000Hz, but what is that short line 500Hz above the fundamental?
 +
 
 +
Here it is again, slowed down by eight times, which drops it by three octaves so that we humans can hear it better
 
and slows it down that our slow brains can follow it.
 
and slows it down that our slow brains can follow it.
 +
They're not harmonics of anything; it's a chord of two notes, with another two fainter ones above and below that.
  
 
{{Spectrogallery|2018-05 Rondone 2018-05 n3 polyphonic call slowed down 8 times}}
 
{{Spectrogallery|2018-05 Rondone 2018-05 n3 polyphonic call slowed down 8 times}}
  
The melody moves between 4500 and 5500Hz
+
The extra notes look equally spaced in frequency. At the bottom of the first trough
and the fainter lines higher up the graph and parallel with it
 
are its first and second harmonics (at twice and three times its
 
frequency.)
 
 
 
But what are those extra notes just above and below the main one?
 
They're not harmonics of anything; it's a chord of at least three notes.
 
 
 
The extra notes look equally spaced in frequency, so it may be that the
 
swift is frequency-modulating its call. At the bottom of the first trough
 
 
about three quarters of the way through, the melody is about 4580Hz,
 
about three quarters of the way through, the melody is about 4580Hz,
 
the line above it at 5050Hz and the one above that at 5600Hz,
 
the line above it at 5050Hz and the one above that at 5600Hz,
differences of 470Hz and of 550Hz
+
differences of about 470Hz and of 550Hz, so it may be that the
 +
swift is frequency-modulating its call, putting a vibrato on the main tone to vary the frequency 500 times a second.
 +
In human voice terms, it would mean being able to wobble a sung note up and down fifty times a second.
 +
 
 +
This *still* means it has two voices, two sound generators: the main one is at about 5000Hz and the frequency modulation (if that's what it is) is at about 500Hz which, to them, is more like growling than singing.
  
However, this *still* means it has two voices. Their main voice is about 5000Hz
+
To a swift, a 500Hz raspberry would be inaudible at a distance, but by frequency-modulating the main vocal chord,
but the frequency modulation is at about 500Hz which, to them, is more like growling than singing.
+
the extra sounds this creates are within the range at which they hear best and would also be audible at a distance.
In human terms, it would mean being able to apply vibrato to a note with the speed of mains hum.
 
  
At a distance, a 500Hz raspberry would be inaudible to a swift, especially at a distance,
+
Clever! Now, all that we oh-so-clever humans have to do is understand what they are saying...
but by frequency-modulating the main vocal chord with it,
 
the extra sounds they generate are within their best range of hearing and can also be heard well at a distance.
 

Latest revision as of 09:31, 24 March 2019

This page has nothing to do with the WikiDelia; I needed to put it here to make playable versions of this study available.

The polyphonic call of the Common Swift

The last few years, I've helped fallen Common Swifts grow and fly again, and In some of the 45-minute breaks I had between feeding them, I recorded some of their chirping, hoping to learn their language.

Instead I found another marvel: they sing more than one note at a time.

Multiple notes or turbo vibrato

Here's the third of a ten-second sequence of fourteen trills from Rondone #3 of 2018.

2018-05 Rondone 2018-05 n3 polyphonic call 0.4s - Spectrogram.jpg

The bottom of the spectrogram represents 3386Hz, the top 16106Hz and the clip lasts 0.4 seconds. The yellow line is the main song ranging from 4000 to 4500Hz and the fainter line above is the first harmonic of that tone, from 8000 to 9000Hz, but what is that short line 500Hz above the fundamental?

Here it is again, slowed down by eight times, which drops it by three octaves so that we humans can hear it better and slows it down that our slow brains can follow it. They're not harmonics of anything; it's a chord of two notes, with another two fainter ones above and below that.

2018-05 Rondone 2018-05 n3 polyphonic call slowed down 8 times - Spectrogram.jpg

The extra notes look equally spaced in frequency. At the bottom of the first trough about three quarters of the way through, the melody is about 4580Hz, the line above it at 5050Hz and the one above that at 5600Hz, differences of about 470Hz and of 550Hz, so it may be that the swift is frequency-modulating its call, putting a vibrato on the main tone to vary the frequency 500 times a second. In human voice terms, it would mean being able to wobble a sung note up and down fifty times a second.

This *still* means it has two voices, two sound generators: the main one is at about 5000Hz and the frequency modulation (if that's what it is) is at about 500Hz which, to them, is more like growling than singing.

To a swift, a 500Hz raspberry would be inaudible at a distance, but by frequency-modulating the main vocal chord, the extra sounds this creates are within the range at which they hear best and would also be audible at a distance.

Clever! Now, all that we oh-so-clever humans have to do is understand what they are saying...