I've recently seen the following image:
Translation (from German):
- The upper boundary (Schmerzgrenze) is where it starts to hurt
- "Musikwahrnehmbarkeit" is where you can hear music
- "Sprachwahrnehmbarkeit" is where you can recognize speech
- "Hörschwelle" is absolute threshold of hearing (ATH)
While the ATH seems to be relatively smooth, there is a noticeable "gap" between 2kHz and 5kHz. Does anybody know why this is the case?
Some possible explanations I've heard are:
- Evolution: Hearing a baby cry
- Evolution: Hearing leafs rustling
- Coincidence: There is no good reason for that.
The image is from wikipedia commons and has no references. It might be wrong. Do you know similar graphs? Do you eventually have this kind of information for other animals?