On a project I worked on not long ago, we wanted to provide audio output: mostly vocal, but the ability to generate music would be nice.

I tried that 1-bit audio, and as far as I was concerned the sound was terrible. Sure you could recognize what was being said, but very scratchy sounding. I also tried the variation, the 1.5 bit sound. Still bad, no real improvement.

The minimum that sounded reasonable to my ears was 4-bit PWM, sampled at 8KHz. Even with that, the data size for even short sound bites was more than I would have like, but further compression on-the-fly required more horsepower than my uC could provide.

Dennis