Sounds of a bat (1) - echolocation sound - 0-2-4-8-16-32-64x slowed down – with notation

Описание: Bat sounds (1) - (Saccopteryx bilineata) - echolocation sound - 0-2-4-8-16-32-64x slowed down – with notation - original position 50-160 kHz / video: 4x slowed down in pitch and tempo = 12.4-39.6 kHz

0:10 - spectrum images original position / 0:26 - video 12-40 kHz / 0:37 - 2x slowed down
0:47 - 4x / 1:02 - 8x / 1:26 - 16x / 2:13 - 32x / 3:45 - 64x (shortened)
5:46 - spectrum analysis of the echolocation sounds G4/Ab4

The bat initially produces an Ab and a G in regular alternation, but not quite evenly. Then it switches on echolocation, so to speak, meaning that the Ab and G become significantly louder, they sound in even alternation with a strong reverberation between the tones and - crucially - the fifth in the second octave is coupled to these tones, Eb9 to the Ab7 and D9 to the G7, both the third partial in the spectrogram (1:3), a frequency that oscillates three times as fast as the Ab and the G. This is followed by a chain of pulsating sounds (semitone glissando G-F#) again with a strong fifth frequency.
In the further octaving slowdown, it can be seen and heard that the Ab and the G consist of a gliding movement: G-Ab---G and F#-G---F#. And when I zoom in even further on the sound, I recognize the sound figures Eb→G-Ab---→G-Eb and C→F#-G---F#→C.
As can be seen in the spectrogram of the 32-fold slowdown below, both sounds form a strong reverberation in which the pitch marker also indicates the semitone movements G-Ab-G and F#-G-F#. The frequency of the G sound (387 Hz) is exactly the frequency at which the sound G-Ab---G (387 Hz) comes into full resonance.
It took me quite a while to analyze these extraordinary sounds and understand their effect. This required an understanding of physics and the spectral order of sounds in order to decipher the “inner workings” of these sounds with the help of filters on the “Overtone Analyzer” and a lot of calculations on the frequency proportions. What immediately became clear to me was that coupling the fundamental tone with the fifth frequency, the third partial tone in the spectrum, is the decisive factor, the “trick” that bats use to create a special spatialization in sound and thus a divergence in the localization of a sound source and its reflections. The fifth frequency vibrates three times faster than the fundamental, has a different vibrational energy, spreads differently, reflects differently from different surfaces, and, in turn, hits both ears at a different frequency in the echo, and each ear differently again. The difference for G in its original pitch is 50 kHz for the fundamental and 150 kHz for the fifth (1:3).

The special voice “skill” of this bat consists in allowing this fifth frequency to emerge quasi independently in the spectrum. The first calls in the recording are very “fundamental,” quieter, without spectrum, and even the locating call does not have a complete spectrum (1st-2nd-3rd overtone – G4/G5/D5 and beyond). In contrast, the sounds made by the pups and the male during mating song cover a full spectrum up to the 4th (2nd octave) or even the 10th partial tone (third in the 4th octave). As can be seen in the “duet” between mother and whelp (video:    • Видео  ), even young animals already have “an ear for the fifth,” which can emerge more intensely in the spectrum when sounding together and can even vibrate more strongly than the fundamental tone. This has a special appeal to the ears and leads to effective stimulation of the vocalization-hearing system.

If I look closely at the spectrogram, the fifth note joins the fundamental tone a little later, stops a little earlier, and has no reverberation. Therefore, I could imagine that this vibration frequency is intensified by sensory activation of the epithelial layer on the vocal folds (“edge vibration”), an energetic efficiency control in a complex, self-organizing system.
I read in a study that the sound of the echolocation frequency comes from the nose of bats. I suspect that in bats, as in all mammals, there is a connection between the inner nasal cavity and the Eustachian tubes (connection to the middle ear), which causes further internal feedback (resonance) of the high frequency and thus an amplification of the interference between the frequencies of the fundamental sound and the echolocation sound (“interference” as an effec and not as a disturbance).

The complete analysis with all spectrograms in:
https://www.academia.edu/144254827/Ba...

other videos:
territorial song -    • Sounds of a bat (2) - territorial song - 0...  
Young animal with mother in vocal learning -    • Bat sounds (3) - Young animal with mother ...  
mating song -    • Sounds of a bat (4) - mating song (♂ / ♀) ...  
call of a young animal -    • Sounds of a bat (5)  - call of a young ani...  

I re-recorded the audio material from the website of Mirjam Knörnschild:
http://mirjam-knoernschild.org/vocal-...

Johannes Quistorp - 2025
https://www.entfaltungderstimme.de/Kl...