The ticking of a clock is quickly pushed into the background for most people, but this sound is enough to distract Sensors from what they are doing. Help them to choose a background sound that is predictable, while blocking out other random sounds around them. Here are a few apps that you can try:
White Noise lite provides ambient noise to block out other distractions. The free version 10 sounds including rain, crickets, chimes, a fan, waves and a train ride. You can mix the sounds, but stick to one sound with Sensors.
You can purchase the sister app called White Noise Recorder. This allows you to record you preferred sounds (a fan you are used to for example). You take 10 - 30 seconds of the sound and it loops it for continuous play.
Piano Classics is a simple piano music box that plays 15 classical music songs including Chopin, Mozart, Beethoven, Schubert and Wagner to name a few. Experiment with which song is the "just right" one.
There are many apps out there that fit the bill for calming, ambient background noise...what have you found as a favorite?