Hi. My understanding of sonar is that the choice of frequency of the pulse, or of the frequncy sweep, is related to the size of what is being sought. That is, a frequency resonant with the range of likely objects, will reflect more strongly, and a non-resonant one be scattered more. Is this true? And does this govern frequency-choice for bats with echolocation? I looked at the relevant Wikipedia pages: http://en.wikipedia.org/wiki/Sonar and http://en.wikipedia.org/wiki/Animal_echolocation but couldn't find anything explicitly about frequency choice in this regard, or resonance.