Vertical scale: frequency (0-2500 hertz); horizontal scale: time (1 frame aprox. equal to 2 seconds); color: signal strength (from lowest to highest, violet, blue, green, yellow, orange, red).
In the above example, an alpha male howls after approaching a
stranger who had howled close to the rendezvous site. The long, low-pitched and
coarse howls seem designed to scare off the intruder without the need for a