How do you hear music and what is it?

How much thought have you given to this, I wonder? 

You walk down the aisle of the church to the music of a string quartet. Perhaps of soprano sings an aria during the signing of the register. Perhaps an organ or a string trio play for the recessional as you exit the civil ceremony. The music is beautiful and adds an extra dimension to one of the most special moments in your life.

 During the drinks reception a string quartet plays on the lawn, the sounds of Handel's Water Music  or a song from the shows comes  wafting across the lawns as your guests chat to each other in the sunshine with a glass of champagne in their hand. Some will be listening to the music while for others it is just an enjoyable background experience, enhancing their enjoyment of the occasion.

Perhaps it is your 40th birthday party in the local village hall, or it may be the evening reception after the meal at which the lounge jazz band played easy listening music. But now it is time for the ceilidh or barn dance. Everyone is excited as they line up for the first dance, the caller shouting their instructions and the Dancers getting in hilarious triangles. Then the band starts playing the music for the first dance and all 100 guests are off stampeding around the Dance Floor laughing and shouting, with the music driving them on.

 Or perhaps you're listening to a cocktail jazz trio in a smoky bar or dancing to an upbeat jazz quartet on the dance floor, listening to the strident sounds for clarinet and Trumpet. Or your ears and whole body may be enveloped in the kilowatts of sound from the function band that is playing at your big celebration, with everyone doing their special thing on the dance floor.


My question to you is, how do you hear the music, why do you hear the music, why does the music make you feel relaxed or excited and why does music cause such a range of emotions? The easy answer  is you hear it through your ears. But that is very simplistic. So let us look at what's really going on when a String Quartet or jazz band plays their instruments and you and your guests at your party or anniversary or wedding or banquet enjoy the music, each in their own specific way.     

What is sound?

Going to the Future to when Virgin Galactic have achieved their goal and they are flying tourists into space. Maybe there will be spaceships licensed for civil weddings? Maybe instead of having an evening wedding reception there will be an evening, night, Morning,  evening and another night wedding reception as the spaceship, with partying guests, orbits the Earth several times.

 Space could become rather crowded with wedding spaceships flying in formation over the Poles and round the Equator, with covers bands blasting away with megawatt equipment in one space ship that is flying alongside another spaceship with a barn dance going on, and on the other side is another spaceship with a Jazz quintet giving it their all.

It's going to get rather noisy in this crowded world, with a poor  couple signing the register at their wedding ceremony to the strains of beautiful string quartet being drowned out by the nearby party band, jazz band and ceilidh band in the nearby space ships.  Or would they?

No they would not. That is the great beauty of outer space wedding venues. You don't need sound limiters to prevent the covers band deafening the neighbours. You don't need the party to stop at 11 in the evening because of the bylaws that Govern nuisance noise. You could have 1000 wedding  going on at the same time all happening in adjacent space wedding venues that are only the width of a road apart and nobody would be disturbed. Nobody would be disturbed by the noise from the surrounding weddings and birthday parties because sound does not travel in space.

 You can look out of your porthole and see a party in full swing through the glass dome of their nearby Space Station, you can see the covers band doing the Rolling Stones tribute, but it will be silent to you.

The reason is that sound is a pressure  wave. It can travel through air, helium, the glass of a window the bricks  of a wall,  but it can't travel through nothing. It has to have some matter, some material, something for is pressure wave to travel through and space doesn't have any of this. Space is nothing. Space is a vacuum.

So Mr Richard Branson has really got the right idea.  None of these problem that you can get  with large wedding venues with three or four weddings going on simultaneously and everybody being disturbed by everybody else's speeches and music. He can have thousands, millions, billions of weddings going on the same time, with bands of every kind that you can think playing simultaneously and no one will be disturbed. Clever guy. All he has got to do is work out how to get people up there at a price they can almost afford and get them back again alive. But that is a minor detail. (With a price of some wedding venues, space wedding could prove to be a cheap option.

When we quote a band or ensemble we include travel costs at so much per mile. I suppose it would be just as easy to include space launch costs at so many million pounds per launch, I'm not sure how software can handle the number of Zeros!

So sound is a pressure wave, a sinusoidal pressure wave. Instruments, that is musical instruments be there a violin, a trumpet or anything else is a machine creating pressure waves in there. Your ears are machines for transducers for picking up pressure waves in air common although it isn't this that causes you to hear music.

So let's look at the pressure wave creating machines, the musical instruments and for that matter the PA systems with loud speakers and amplifiers that some musical groups like covers bands we use to make very loud sounds ie pressure waves with high pressure differentials.

The sound machines of a string quartet

The sound creating machines of a String Quartet, string trio or for that matter a harp, piano or guitar all work in basically similar ways. They are all stringed instruments.  A piano  is sometimes listed as a percussion instrument. This is because the Strings of a piano are hit with a hammer mechanism much like a drummer hitting their drum with a drumstick. But to me this is illogical. You don't say a harp is a plucked instrument or pulled instruments because the strings are plucked, as also done with a guitar where plucking and strumming are all ways of Exciting vibrations in the string.

Violins and cellos are sometimes termed bowed instruments, but sometimes they are plucked like a harp, so that is not very logical. So to me the important thing about all of these instruments is that they rely on tensioned strings to create a vibration.  The vibrating string itself can cause sound to be produced, but the string is such thin and small object that it can't do very much moving of the thin and low viscosity air. However it can transmit significant vibration through wood and metal and so a soundbox is always used. A soundbox is a device to create a large vibrating surface area which can in its turn vibrate a large amount of air. So let's look at the process of creating sound from a stringed instrument.

You want to produce pressure waves, which are vibrations in the air, so that these vibrations can be transmitted to your ear. You have to start off buy vibrating something. in a string instrument that something is the string. A string is simply long thin flexible object, as string in other words, that is put under tension. There are various parameters connected with how fast that string will vibrate.

As the string is pulled tighter and tighter the frequency of the vibration, or how fast it vibrates, increases. Also, as the string gets heavier, so the Frequency gets lower. High frequency equates to a high note low frequency equates to a low note.

The length of the string also affects the frequency of its vibration, the shorter it is the higher the Frequency, the longer it is the lower the frequency.

So for now ignoring how we get the string to vibrate, let's look at the physics of a string.

 The equation for the vibration frequency of a string is explained in the following video: