When you get done practicing for the day, you can always log on to C&F, throw a lump of red meat into the arena and enjoy the feeding frenzy. When your thread stretches to seven or eight pages, you’ve found a good one.
Noticed that you also have a violin on your picture. I also play fiddle and believe me if you do not bow right the note can come out scratchy and screaming. I think the whistle is just getting a bad rap. They probably just do not care for it. Like bagpipes…either you love em or hate em. 
I think it is great you are trying another instrument. I also have played flute for most of my life and now have started the whistle. If you feel it is too loud there are much quieter ones out there to try. Just let go and enjoy!
I know what you mean. I get that comment about my whistle’s being children instruments. But I don’t care I don’t play for them, I just really enjoy sitting and playing.
I remember when I first was trying to learn to play many didn’t like the high pitch sound. I’ve noticed as I’ve become more practiced that it’s not as bad but I still practice were no one can hear me. I find if I just play one or two songs when I’m in front of people they give me more praise. If I go much further then that they start to get annoyed
The whistle is a pretty high pitched instrument, and when played by those of us who are not adepts, those high notes can be a bit piercing, so there is some credence to be given to the notion that those who are an unwilling audience may find it less than pleasant. So it is wise to do your practicing in more private surroundings, and only take your best stuff to the public. However, there is also a strata of human beings that are more curmudgeonly than appreciative, even when confronted with great players, so it’s not all black and white. There will also always be those who think you are a breath of fresh air, even when you thoroughly embarrass yourself. In the interests of honesty in critique, throw out both the extremes. 
If the glare-ers are regularly near, just go play somewhere else. However, if they are not higher ranked on the seating roster, let them go somewhere else, and play. And practice, practice, practice, so that your music is always getting better. Folks will notice.
Oh, and on that ‘child’s instrument’ comment… HAH! You might just offer them your whistle, so that they can show you how it’s done. 
theres a wee bit of a child in all of us 