Asked by: Stephen Ward, Poole
Answered by: Dr John Powell, a Visiting Professor of Materials Science at the University of Nottingham
Hear the noise
The sounds of music are not the same as noises. Your ears are there to make sure you stay alive: they're a warning system, designed to analyse sounds for danger. But we can quickly recognise that a musical instrument is unlikely to be lethal. When you hear music, your ear drum moves in and out in a regular, repeated way, many times a second. We recognise that it's not dangerous, so we can focus on the harmonies and tunes – and enjoy them.
If you twang a string, it gives off several related frequencies at the same time. If you twang a second string, and organise it so that some of the frequencies of the two strings are the same, you get a very pleasant sound. We don't always want notes to agree in this way, but we do most of the time. We appreciate a little bit of tension, but then you need to get some sort of resolution through pleasant combinations of sounds.
Melody feels good
There is a physical basis behind the punctuation we feel in the phrasing of melodies and harmonies. The enjoyment of music is largely down to the building up and release of tension. In a piece of music, there is a key note which is 'home'. We arrive home at the end of many of the musical phrases. Also, the note just before the home note gives us an "almost there" feeling. An easy-to-follow tune is often very clearly punctuated, meaning we can almost anticipate the notes – and follow the 'conversation'.
Keep us guessing
There are many sorts of music, and we enjoy them in lots of different ways. In film, music echoes the action. Several clichés have been built up – like strings and piano for romantic moments – but we enjoy them. In some cases, the music builds tension and we enjoy guessing what's going to happen next. If you look at "serious" music, like classical or jazz, anticipation and release are a major part of our enjoyment. The composer or improviser will set up expectations and then either reward or frustrate them. It's like telling a joke, where the punch line either fits the story, or is a surprise: in both cases, we get pleasure.
Drumming was probably the first sort of music; hitting things with a stick is fairly easy. Rhythm is good for dancing or entering hypnotic states, so that's an ancient response that we have to music. Our enjoyment of dance music is simple to understand: you can't really dance without it, and we enjoy dancing. Pop music involves short, ear-catching, easy- to-remember melodies. It's like eating sweets: instant gratification.
Musical systems are learned at an early age. Babies will sing several hundred different notes over a few minutes. But that song can't be repeated, so it's not much fun. The baby then listens to its parents singing nursery songs which only have a few notes, so the baby can learn to remember them and enjoy them.
A pattern emerges
Western music uses a lot of harmonies, where all the notes used at any one time agree with each other to some extent. Other musical systems are slightly different.
Think of a team of five planes doing an aerobatic display. They have two ways to impress the crowd below. They can all follow a sequence of complicated, but carefully organised, patterns, or four can follow a very simple pattern while one soars above very freely. They can't all go free or it would be messy chaos.
Western music has chosen the former system, with everyone playing a limited selection of notes. Indian traditional music is of the latter type, which is why you often have drums and a simple drone accompanying a soloist who has a wide range of notes and flourishes.
There is no scientific reason at all why you'll prefer one type of musical to another. Everybody could enjoy more kinds of music if they gave them a chance – but sadly we tend not to do so. With food, if you try something properly 10 times you'll probably come to like it. It's the same with music, but people often close up their range of musical appreciation by the time they're about 25. But it's easy to increase your enjoyment of life by listening to a lot of different types of music. Mozart and the Arctic Monkeys and Dolly Parton? Go on – I dare you.
Dr John Powell is author of 'How Music Works', published by Penguin on 26 August, £12.99. Send your science questions to email@example.com