This voice changer from the 1990s uses one of OKI's famous voice changer chips.
This same chip was used in Casio's RAP-1 RapMan keyboard.
I was wrong in my video, I didn't look at the right web page to locate the RapMan voice changer chip.
These DynaMikes are then a very cheap way to get the RapMan voice changing effect.
The one IC is the JRC386D. This is a 0.5 watt amplifier on a chip. More than enough to drive this little speaker.