Finished a penny whistle this afternoon. This is my 3rd whistle. This one is a gift for my daughter.
I’ve been playing it, and my wife has been holding a cat over each ear to block out the sound (it’s pretty shrill).
Apologize for the quality of the recording. I recorded it on my mp3 player. The little mike wasn’t up to the task.
Is it PVC? 
What are the dimensions of your windway, and how far is the fipple block from the blade?
Shrillness in higher notes can be due to too much space between the fipple and the blade.
It’s copper. I’ll have to get the rest of the dimensions later, since it’s currently at work.
Your whistle holds down a job?
There would be nothing wrong with a whistle being gainfully employed as a paperweight or some such light duties. Afterall many whistles are too slight of build to do such duties as Door Stopper, and it would be entirely unfair to ask this of any gainfully employed whistle. In this day and age hoop you just can’t descriminate.
Mick
True, Mick. I’ve heard of a few police whistles in my time…
Here’s a better clip of the whistle…