CNN just ran a video with the ULB pings in audio coinciding with a waterfall display. I have been unable to find this on the net - I would have expected it to be at JACC's media documents. Does anyone know if it is available.
The video is quite compelling. You can hear the very regular clicks. On the display, you can sometimes see weaker clicks at different times, which could be the other ULB, or could be natural - I couldn't tell. They mumbled that the clicks were computer generated, whatever that means.
Others here with more sonar experience than me might be able to add to this.
The CNN report is at
http://www.cnn.com/2014/04/08/world/...html?hpt=hp_t1
[Note: other link went bad, edited for new one. This shows much less of the pings, but it is there]