For the most part like a less dynamic modem. Less EEEE-OOOO-SCRSHHHH and more EEE-EEE-EEE it had a base tone of something middle-c like (can't recall, it was 20 years ago now) add just added the byte value with a modifier on top of the base. So for long stretches of it it was just to my ear pretty much the same sound, especially when transmitting ascii text.