I tacked this one on a board tonight. It drives a 2" speaker to room filling volume. I changed R2 to 200 Ohm. I didn't see any 100 Ohm in the drawer and was not going to the shop to get one.
I connected an ear bud to the output and an antenna coil and diode on the input. It plays radio (weakly). It could use a little more signal than I got with my clip lead 'radio'. That would not be hard to do. It draws around 10 ma with no signal at 6 volts.It will work at reduced output with 3 volts.