Most squarebills on the market today are either silent or have a weak, singular pitch. Coming from the Godfather of sound-fishing---Rat-L-Trap---the Echo features dual chambered bio-acoustics. On a slow retrieve the ECHO hits a low-pitch knock, but when you rip it free from grass or speed up the retrieve the high-pitch rattle chamber prevails. We found in cold or stained water the slow, low-pitch works well, and in warmer water the faster, high-pitch retrieve heats up.