I have been thinking a lot about the birth cry. Perhaps because there is a rush of spring babies arriving round my way, or perhaps because people reading my book seem to latch on to what I say about it in the opening chapter – that the pitch of the average baby’s first cry (or ‘vagitus’ as the Romans called it) is very close to the note used by orchestral instruments tune to one another (often known as Concert A). The average vagitus vibrates at 450 cycles per second (or what it technically termed 450 Hertz), whereas 440 Hz is where every classical concert begins. You know the form: the leader of the orchestra stands up, turns his back to the audience and points with his bow towards the wind section. The lead oboist licks their reed, clenches it between their lips and launches forth their purest, most assertive A. Everyone else then gets busy making sure that their reeds or mouthpieces or strings are emulating that tone.

The reason the note is A is that string instruments (who traditionally constituted the main body of the orchestra) conveniently all have an A-string. They’ve handed the tuning job to the oboe because its pitch is stabler than theirs, plus its singing (not to say, piercing) tone rises easily above the melee of your average band, hanging out before a gig.

Most musicians aren’t very bothered about frequency measurements; they prefer to trust their ears rather than the numbers Hertz might give their notes; but they do know A440. Since 1936 it has been the standard frequency for orchestras in the US, and twenty years later across the rest of the western music-making world, though European instrumentalists allow themselves some lea way, taking their pitch levels up to as much as 444 Hz. Which begs the question, why do we have to have standardisation at all? What is the point? As long as a group of instruments playing together are tuned to one another, what does it matter?

The truth is that pitch tuning used to be a highly relative affair. When Mozart was touring around Europe, they used to perform his pieces at radically different pitch levels (often many tones apart) depending on the local norm, generally set by the tuning of the church organ. There was also seasonal variation as stringed instruments expanded in the heat of summer and shrunk in winter (making them accordingly flatter or sharper). There was also simply a matter of taste – some people like bright, others prefer mellow. Apparently the British Library in London has a tuning fork that belonged to Beethoven which it pitched at A-455.4. And why might Herr Ludwig want his A so much higher than everyone else’s? I wonder if his tinnitus has something to do with it…was this frequency the one that managed to cut through the noise?

Or it could have been something to do with the loudness war? Because it’s not just in the 21st century that such things mattered. Even in the days before mics and sound mixing, music makers were constantly competing to get across the footlights. Their version of turning up the volume was to use pitch inflation, meaning they made everything just a tad sharper, then a tad sharper again… At the beginning of the 17th century, Michael Praetorius reported in his encyclopedic Syntagma musicum that the pitch level was more than a minor third higher than today’s (or around 525 Hz). The performers who complained about it the most were, of course, the singers whose throats were under serious strain. Eventually, the music authorities had to step in and standardise something lower before everyone lost their voices.

Things have gone up and down ever since. In 19th century Britain Concert A went up to 552Hz, but eventually the tenors went on strike, and around 1900 it was lowered again. Who knows where we will go in future. While baroque musicians stick determinedly to a lower pitching level (because their gut strings can’t cope with anything higher), the rest of us are said to be on the rise. New instruments are being invented all the time, ever more versatile and resilient. Technology advances. The sound of an orchestra could just keep getting ever more vibrant. Except for one thing – the singers. Their instruments are more soft than hard-ware; they can’t be industrially engineered; they can’t be made to tighten up and up. Once we singers are in the music-making mix, there has to be some sort of standardisation; we need a frequency at which our instrument can be expansive, expressive and generally useful. That’s why the average orchestra, however caught up in their own version of the loudness war, needs A440. If they feel that the involvement of singers makes their music less exciting, they also need to realise that it is more accessible. Because it relates every one of us, audience and performers, back to the vagitus – to the first pitched sound we ever made.