Comment by egypturnash

It’s a c64, there are no samples*.

https://linusakesson.net/scene/a-mind-is-born/ has a full breakdown of what is going on.

What you call the “heartbeat” is, I think, what Linus thinks of as “drums”, and is a rapidly descending tone in (probably) a rectangular wave - the c64 cannot generate sine waves, just sawtooth/triangle/pulse, and random noise (and some combinations of these that were not intended by the sound chip’s designer). In addition all three voices of the sound chip are being pushed through its subtractive filter, which is a hard-to-emulate bit of analog circuitry that gets noisier and noisier if you out more than one voice through it.

If you really want a close look at what’s going on you could download the “SID tune” version of it and run it through a c64 music player, most of these have oscilloscope views and the ability to selectively mute voices.