Earth Mountain is making the dream come true, page-111

They're referring to the Yuval video. Yuval played a 10 second snippet taken out of the middle of a Nora Jones song 'come away with me'.
There was a background noise like a low level hiss. A few times I listened carefully to the end of the recording and after the song stopped abruptly (because it was a snippet from the middle of the song) the background noise continued for a half to one second.
Yuval had obviously turned the chip off (you could actually hear the chip being turned off and at the same moment the song ending abruptly) and then a second later he turned off the microphone/recording device.
It was clear the ambient background noise was not coming from the chip but the microphone/recording device.

If you could ignore the background noise - albeit easier said than done, the chip sounded fine, it had a depth and clarity to it for something so small, I presume due to the low frequencies achieved. It wasn't very loud but it may have been a Gen 1 chip for headphones or it was just the way Yuval set up the recording.