My shower makes a high pitched whistling noise. This doesn't happen all of the time, and seems to be more pronounced when changing the temperature from hot to cold. It may come and go, or may make the noise during the duration of the shower. Any thoughts on what could cause this?
Any help would be appreciated.

What's the brand and age of your shower valve? Tom

I bought the place new a 1.5 years ago, and it still has the builder installed parts. I know the shower head is Kohler, but that is all I know off the top of my head. Can check when I get home.
Thanks!

Can check when I get home.
Please do. Is it temperature controlled? Squeels, whistling and rapid knocking noises are caused by vibration in the valve. I need to pull up a diagram of the valve to nail it down. Regards, tom

I will check the specs when I get home and let you know. There is never a banging sound, just the intermittent whistle sound. It seems to be more pronounced when it is cold outside and the water temp is changed to allow more cold water through.
Thanks again!
Carrie