Can Ultrasonic audio past an objects?

[Shannon]

Audio is audio. It is energy, which travels through vibration of the materials between its source and the reception point. Different frequencies have more or less energy; different materials absorb more or less energy. Pillows tend to absorb a lot of sound, which is why they have been used as "poor man's silencers" for a long time.

I do not recommend using pillow speakers.

Pillow speakers are possible to use if:

1. You know for absolutely certain that it is stereo, not mono.
   
2. It has volume that allows for the projection of audio through your pillow such that you can hear words reasonably clearly from audio that is not ultrasonic.
   

However, this leaves you with a high volume audio being projected right at your ears that may or may not be louder than normal audio because it may be less absorbed than normal audio by the pillow.

In the absence of some way to actually measure the volume at the surface of the pillow (FrequenSee), you should not use pillow speakers. Even then, don't allow the audio at the source to exceed -32 dB at a maximum. I recommend -35 or -40 dB.