Ultrasonic should be safe with headphones if you first calibrate volume using the trickling stream and ocean surf tracks. That will be the same volume the ultrasonic plays. But headphones are easy to have fall off while you sleep, and ultrasonics are easy to over or undervolume with headphones on, so if you go that route, please be careful.
Subliminal Audio Specialist & Administrator
The scientist has a question to find an answer for. The pseudo-scientist has an answer to find a question for. ~ "Failure is the path of least persistence." - Chinese Fortune Cookie ~ Logic left. Emotion right. But thinking, straight ahead. ~ Sperate supra omnia in valorem. (The value of trust is above all else.) ~ Meowsomeness!
The scientist has a question to find an answer for. The pseudo-scientist has an answer to find a question for. ~ "Failure is the path of least persistence." - Chinese Fortune Cookie ~ Logic left. Emotion right. But thinking, straight ahead. ~ Sperate supra omnia in valorem. (The value of trust is above all else.) ~ Meowsomeness!
