Musical balloons

Hi,

I've just registered as I suspect this is a good place to seek my answer.

I am trying to find some information on 'how' something worked, which I have just a vague memory of from when I was younger, which I saw on a kids science television program. This would've been on during the 90s in UK, and it wasn't Blue Peter.

On the show, they demonstrated the playback of an audio cassette using a balloon.

I don't recall how, though have a slight memory which involved scraping along the cassette tape ribbon, and the audio being played back via the balloon.

Does anyone recall this per chance, or know how a cassette could be played back using a balloon and ... some other implements.

Certainly no electronics were used.

Would be great if anyone can explain, so I can look this up further, and perhaps even experiment myself.

Thanks.