This is a deceptively simple question. Will some of you will answer “3:30” without hesitation? Do you even have a standard length that you aim for?
Nothing wrong with having a standard length, by the way. Some genres call for it. Hard to have a club hit that’s 2:30 (unless you have an extended version just for DJs). Hard to have a pop hit that’s ten minutes long (unless it’s the extended video version). Chances are your saga about wizards and dragons won’t fit in less than five minutes (fifteen if you’re wearing a cape).
But even within stylistic constraints, you need to pay attention to length. This is because the length needs to be considered together with the quantity of musical material in the song. This is called coherence. Basically, it’s the trade-off between musical material and time.
- A song has low coherence when it has a lot of musical material squeezed into a short time.
- A song has high coherence when it has not much musical material stretched over a long time.
You should aim for a balance between the two.
A song with not enough coherence will have too much material and not enough time to develop it. The song will sound fragmented and unfocussed. Listeners will be confused and disoriented.
Conversely, a song with too much coherence will have too much time and not enough material (or development) to use it effectively. The song will sound boring and undeveloped. Listeners will be bored and will probably not wait to listen through to the end of the song.
What’s the right balance? You have to be the judge. You have to use your experience and judgement to decide what the right balance it. Fortunately, finding that balance isn’t difficult – after a lifetime of listening to music you should have a pretty good sense of what level of coherence to aim for. If you haven’t got it right in the past, it’s probably because you simply haven’t been aware of it.
So what if the song you’re working on isn’t quite there yet?
If your song is sounding fragmented or there isn’t a clear musical language, you probably need to increase coherence. You can either increase the length of the song (to let the material develop a bit further) or you can remove some of the musical material (which in turn gives the remaining material more time for development).
If your song is sounding boring or your musical material is dragging on, you probably need to reduce coherence. You can either reduce the length of the song (to make it tighter) or you can add new musical material (which adds more breadth and variety).