04-10-2014, 09:07 PM
You choose ultrasonic if you prefer not to hear anything. I sleep with the trickling stream and it doesn't bother me at all.
Don't use ultrasonic with headphone it's dangerous. Use speaker in stereo if you are listening to ultrasonic.
https://www.google.com/search?q=site:sub...tful+Sleep
https://www.google.com/search?q=site:sub...a&safe=off
Don't use ultrasonic with headphone it's dangerous. Use speaker in stereo if you are listening to ultrasonic.
https://www.google.com/search?q=site:sub...tful+Sleep
https://www.google.com/search?q=site:sub...a&safe=off
