I notice (Sep 2017) that the program below is not running. But THIS one of May 2016 seems to run:
Too busy now to fix this.

This is an active (not yet on smart phones) demonstration program that allows some testing of concepts related to determining sources of waves. In writing it from scratch in Feb-Mar 2014, I taught myself some javascript programming using HTML 5's "canvas." It is primitive, but shows some real facts. It shows some things that can go wrong. It also shows a fact about reflections from rods that I discovered and do not know if anyone else has noticed. Can you see an inversion, of the click, in the echoes? Also, it shows "cross-sensor ambiguity."

Instructions for students:
Decoding the Sonic Vision of Dolphins

Left-click in the left box, then
For style, use A, D, H, R, and space-bar.
For ScienceParms, use arrow keys, L, N, M, R, and space-bar.

The signals are discretized, so, the toas are not perfect.

Determine the region of good performance - wherein
the red lines cross near to the Target. Discover places
where our code needs improving.

May 2016 Sample. This seems to run.