I learned the hands free approach as a kid (no assistance, just experimentation). Now I can reach ear piercing levels that temporarily damage the hearing of tho

I learned the hands free approach as a kid (no assistance, just experimentation). Now I can reach ear piercing levels that temporarily damage the hearing of those within 5-10 feet using either a 3-5 second burst or 10-15 second sustained whistle. I've found it makes for a very effective training mechanism with dogs.