> Because it works by exploiting this leakage, Time Station Emulator works best with a built-in speaker of a phone or tablet.

> In some cases, wired headphones or earbuds may also be suitable.

> Higher-frequency harmonics are considered artifacts beyond the range of human hearing, so they are routinely suppressed by audio compression algorithms and better equipment.

> Bluetooth devices and audiophile-grade equipment are therefore less likely to work.