Picture 1

0712-1 sound (4s, 30 kb mp3)
Echolocation pulse train followed by a buzz-stop. The pulses are emitted around 9 per sec, and each pulse contains discrete frequencies bands reaching up to 35 khz. The last buzz contains a broad continuum of frequencies centered on 80 khz (see below).


Picture 1b

0712-1 sonogram.
The time vs. frequency plot, or sonogram. One of the pulses has a bright spot around 2500 hz and the last buzz is broadly centered between 5000 and 6000 hz. This corresponds (x16) to ultrasound frequencies of 40 and 80-96 khz, resp. (The individual frequency bands within each pulse appear to change but this is in large part due to the detector's directional sensitivity.)


Picture 2

Closeup of 4 pulses from Picture 1. Smaller secondary pulses are seen to appear between the main pulses.


Picture 3 -- Time axis in audio samples, 32000 samples = 1 sec

A single pulse and its smaller companion. The frequency within the main pulse is about 6 cycles over 100 samples. So the corresponding ultrasound sound is 6*32000/100*16 = 30720 hz.
The length of each pulse is close to 200 samples, or 200/32000 = 6.25 ms.
The pulse rate is 4 per 0.5 seconds, or 8 per second.


Picture 4

Seconds 3-4 of Picture 1: the buzz-stop.
0712-1c sound the buzz-stop only.


Picture 5 -- Time axis in audio samples, 32000 samples = 1 sec

Closeup of the end of the buzz and the stop. Between samples 18900 and 19000 there are 16 cycles, so the dominant audio frequency in this region is 16*32000/1000 = 5120 hz. The corresponding ultrasound (x16) frequency is 16*5120 = 81920 hz.