Jim,

Pheasants have acute hearing and are aided by pads on their feet that sense vibrations helping them detect the approach of a preditor. They can hear a high pitch dog whistle. I applaud your decision to keep quiet in the field, nothing is worse than listening to somebody hack their dog.

I solved the whistle/noise problem another way. In addition to being whistle broke, my dogs are trained to obey the tone on their Tritronics Pro-100 collar. This tone does not shock the dog.

Example, a series of short tones is "here", one long is for a release, and two longs are for whoa. It's nice because the collar works up to a mile away. Also, on windy days the dogs have a tough time hearing a whistle from more than a 150-200 yards.

Lastly, with ringnecks, I have found that whistles often don't bother/spook them. Can't say why.