If you have an easy set pool with a plastic rim filled with air around the top which actually holds the pool up how do you find a hole in it if you've tried dish soap but to no avail?

Hi. I have had this happen before and I found the hole by putting my ear aganst the plastic and listening to where I thought it was. I was able to just about pin point it. Then I used the soap to see exactly where it was. I have also heard that this pools have a problem with leaking at the valve where you blow them up. You might want to check there.