A ritardando is a gradual slowing down within a piece of music.

If Pop and Classical Music were bicycles, then classical would be the one with the 21 gears and complicated braking mechanism, while pop would be the solid fixed-wheel.

A classical piece may have one basic tempo – just as most cyclists have a preferred cruising speed – but the potential for variety is huge. A pop-tune is one-speed: and if your aim is a good burst of tension-relieving, social ice-breaking dance, then you probably wouldn’t want it any other way.

It affects the expression fundamentally: pop-tunes by and large convey one simple mood; a classical piece can suggest a much more complex emotional storyline, exploiting memory, playing with the passage of time, possibly provoking reflection.

One of the classical musician’s most basic time-and-motion defying tools is Ritardando: literally ‘holding back’ or ‘held back’.

OK, there have been pop musicians who’ve exploited the big ritardando to make a grandiose ending (think of the final bars of ‘Bridge Over Troubled Water’) and Heavy Metal drummers have long recognised its attention-grabbing pay-off potential.

But pulling back the tempo within a pop song is almost unforgivable – the beat must go on, and it must be regular. There are performers who take the same line with Baroque music too.

The problem for us today is that composers of Bach’s time – and indeed of Haydn and Mozart’s time – rarely thought of indicating small-scale modifications in tempo. Pause signs are about the only exceptions, but do they simple mean ‘pause here’, or do they imply some sort of preparatory slow-down?

Generally, it would seem that 18th- and early 19th-century composers took it for granted that musicians would know where to hold back and where to keep up the pace.

It was Beethoven, that restless striver after notational precision, who increasingly indicated ritardandos – which begs the question: if he doesn’t mark ritardando does that always mean that he doesn’t want it?

And what about the abbreviation rit.? Does that always signify ritardando (a more-or-less gradual slowing down) or ritenuto (a much more immediate foot-on-the-brake effect)?

On top of this there seems to be a natural tendency for performers to anticipate a ritardando – I knew one composer who always put his rit. sign a bar later than the point where he actually wanted it to start, ‘because that way the players will probably get it right!

This article was first published in the August 2011 issue of BBC Music Magazine