When I add a gap to the start of a paragraph, I'd like it to be not 100% silence, as in the complete absence of sound, but only lack of voice. I'd still like a sound.

I would like to insert silence as a very low-level hiss, just enough for the sound system to play it back and keep the Bluetooth headset alive. Barely audible.

It's because Bluetooth headphones aggressively throttle the connection as soon as no activity on the sound system is detected, so often the first bit of a word after a period of complete silence is lost as the headset powers the connection up again.

I can do that right now by hacking it with my own 15-second .wav loop of impedance noise at about -30 dB or perhaps less.