Other spectrograms of undetermined sounds.

 

Trivial: What sound can this be ?

Tip: It is an audio registration from an old (Vacuum Tubes) radio, probably tuned on a short wave station.

 
 

This is a strange sound that a friend gave me, you can see below the spectrogram of a few seconds of this sound, and by clicking on the image you can also listen to it.

Screen capture of the spectrography of a strange sound

Looking to the above picture (obtained with another software) you can roughly see the frequency range and the repetition time of the sound.

Monsters spectrogram flipped 90°

While working to decipher the sound I noticed that flipping the image 90° would have given something vaguely similar to a monster or a monkey, here is a selection of the above sound, taken with other settings so to enhance the similarity.

If you click on the image you will find a VERY LONG selection (1.63MB MP3) of the sound.

Cleaned up monster

Here is a "cleaned up" version of the above image, the cleaning here refers to the picture and not to the sound, if you use a spectrograph on this sound you will get an image similar to the one above.

If you click on the image you will find a VERY SMALL (20KB MP3) file of one monster repetition only.

Can anyone guess what kind of sound it is ?