The frequency of whistles is specified in the US inland version of the ColRegs Annex III:

It describes the fundamental frequency, and range. In summary:

over 200 meters 70-200Hz 2 miles
75-200 130-350 Hz 1.5 miles
20-75 250-525 Hz 1.0 miles
under 20 250-525 Hz 0.5 miles

It also describes the volume of various overtone ranges. For the large ships this is
140-145 dB. For the smallest is 111-120 dB.


wrote in message
...
On Fri, 01 Aug 2003 13:05:34 -0400, Gerard Weatherby
wrote:

On Fri, 01 Aug 2003 11:09:25 -0400, wrote:

Not really. The ability to determine the source of the sound is determined by
the receiver, not the transmitter. Our ears are too close together to get a
bearing on low frequency sound.

That would make it patently less directional. 8^)

If you assume human ears are the only way to receive sound

The context is foghorns, which are usually there expressly so that
humans can hear them.

BB