The Frequensee app isn’t in the US iOS App Store any longer.
I found out because my phone is set to offload apps that haven’t been used in a while. To save space.
I went to redownload the app to check ultrasonic volume and it isn’t there anymore 
Just saying here so the listening instructions can be updated sometime.
Are there any alternatives that you (or anyone else) have discovered?
I found this one so far. First one I found that didn’t want to charge a subscription to use. I don’t swear by it yet. Verdict is still out.
I do use this one for one and a half year now, it works great.
Yes everyone. That’s why I said “iOS App Store” 
I worked at Apple and know the difference 
I just figured the instructions would be better off by generalizing and not mentioning a specific app by name.
