A song is a collection of musical notes, arranged in a pleasing order, with words, which someone sings. Something like that, right? More or less, but there’s so very much more to say about them than that. About everything that goes into making up a good one – the way it is written, performed and listened to. Which is what musician and composer Neil Brand is doing here, in Sound of Song (BBC4).

It starts off in part one (of three) with how songs first came to be recorded. On tin foil, that’s how Thomas Edison first did it. Well, music is a kind of drug, I suppose. Actually, Edison wasn’t even thinking about recording music, but office dictation; it was an early dictaphone, basically. But people, Edison himself included, soon realised that songs were a lot more fun than secretarial work.

Wax cylinders replaced the foil. You could just about fit one song on to a thing the size of several iPods, so long as it was a very short song. But “Wanna come home and listen to my wax collection?” never really worked as a chat-up line. So records followed, which had a better frequency range. High notes and low notes worked, too, as well as the ones in the middle. Recording songs also got better. Crowding around one big recording horn had its limitations. The microphone was invented, and that led in turn to a new way of singing, called crooning. It was soft and low and very sensuous. Absolutely disgusting, some said. Bing Crosby was basically the devil. Ha!

Well, we laugh now, but in another 70 years, garage and grime will probably be songs for the oldies. Turn your rap down, grandad. And less of your twerking, grandma, we’ve got homework to do.

It’s a detailed, thorough – very thorough – tour. But Neil Brand is a good guide, picking out a tune on the piano, trying out some early equipment, digging around in this archive, speaking to that expert. Plus there are some lovely recordings and clips – of Louis Armstrong, Bessie Smith and that wicked Bing Crosby in this opener. Actual songs, to bring it all to life.