Revolutions in sound recording
1 Capturing sound
Have you ever listened carefully to a recording of your own voice?
In this first activity, I want you to make a short recording of your voice.
Activity 1 (Optional)
Note: This optional activity requires the use of a computer microphone and sound editor software, such as Audition or Audacity, which is free to download from audacity.sourceforge.net.
Using the equipment noted above, make a recording of yourself reciting the following well-known children's nursery rhyme:
Mary had a little lamb, Its fleece was white as snow.
And everywhere that Mary went The lamb was sure to go.
The reason for this choice of rhyme will become clear in a moment. Play the recording back to yourself. How do you sound? Do you think your voice sounds like you?
Well, do you think your voice sounded like you? Probably not – due to the directivity of the voice, you do not hear it as others do and so it sounds unrealistic to you in a sound recording. However, because you know that the technology you are using is capable of accurately reproducing sounds I hope you have confidence that what you are hearing accurately represents how you sound to others.
The first sound recording of a human voice, actually reciting the nursery rhyme ‘Mary Had a Little Lamb’, was made over 125 years ago. Just imagine back then the reaction of people the first time they heard the sound of a human voice coming from a machine – especially if it was theirs!
The phonograph [recording machine] was remarkable partly because it did not look human – it spoke just like a person, but it looked like a machine, a simple cylinder of tinfoil.
Wood, G.,2002, Living Dolls, London, Faber and Faber, p. 121
So great was this invention and so insatiable was (and still is) our need to hear recorded sounds – especially music – that within 25 years sound recording had become a global industry.
Before sound recording was possible, few people had the opportunity to hear music in the way we take for granted today. Apart from expensive musical boxes and mechanical music players, the only way music could be heard was in live performances. Take a moment to think how your life would be without being able to listen to music from CDs, records, tapes, radio, television or even the web. How often would you listen to music if you could hear it only by attending live performances or making it yourself? The following activity asks you to think about listening to music before sound recording was invented.
Think of how people listened to music before the advent of sound recording. Try to put yourself in their place and make a list of the various ways in which you might hear music. Is there a common thread that you can discover about the experience?
I thought of the following:
places of religious worship (singing hymns, listening to the organ, etc.);
at school (nursery rhymes, group songs and dance);
in the home (barrel organ, musical box or player piano);
live concerts (listening to the band in a local park, going to the music hall, a classical concert or a musical theatre performance);
dancing (to music from local bands).
A common thread that occurs to me is that on many occasions music was created by people (amateurs rather than professionals) meeting together – at church, school or the local public house for example. Most of the music was live, with just the possibility of hearing a mechanical instrument such as a barrel organ.
Another very significant factor is that, as you have just seen in Activity 1, recordings have allowed performers to hear what they sound like to other people. In his book, Robert Philip says:
Musicians who first heard their own recordings in the early years of the twentieth century were often taken aback by what they heard, suddenly being made aware of inaccuracies and mannerisms they had not suspected.
Philip, R. (2004) Performing Music in the Age of Recording, Yale University Press, p. 25
He goes on to argue that the effect of recording has been to change many features of general performing style. Before recording was possible, when a single performance of a work might be the only chance many listeners would have to hear that particular work, performers tended to play in a way that would now seem exaggerated and mannered, such was their determination to underline the music's expressivity and its major structural features. This style of performing survived into the twentieth century, and can be heard in many early gramophone recordings. However, the spread of recordings, and the opportunity they afford for the listener to become familiar with a large body of repertoire works, has fostered a performing style that is less concerned with pointing up salient details of the work (which many listeners now know from recordings) than with eliminating mannerisms and imperfections from the performance. Philip argues that in the age of recording, performers have become especially concerned with precision and accuracy, whereas performers (and listeners) of the past placed less value on these qualities.
You may already know that sounds from any source are conveyed to our ears by small variations in air pressure. These variations, which are captured by the eardrum, cause impulses to be sent to the brain, allowing us to make sense of the sound. We cannot store the sound but our memory allows us to recognise it if it reoccurs. A microphone also contains a membrane, called a diaphragm, that responds to the variations in air pressure by generating tiny electrical impulses, which may be amplified and recorded (or stored) by a suitable medium. Playing back the recording, again by using a diaphragm but this time a cone in a loudspeaker, regenerates these variations in air pressure with sufficient energy so as to act on the eardrum in the same way as the original sound. This makes the recognition of the sound possible, as if it came from the original source. In order for us to believe we are listening to the original sound, the recording and playback systems must not distort the original signal in any way. The next activity revises the three main parameters that determine audio system quality, and these will be used throughout this unit as a means of comparing the quality of the various different audio systems that are discussed.
Bandwidth, dynamic range and signal-to-noise ratio are three parameters that can be used as a measure of the quality of an audio system. What do you understand by each of these terms, and what is considered a rough acceptable value of each of them for a good-quality audio system designed to play CDs?
The bandwidth of a system is the range of frequencies over which an audio device responds equally (i.e. has a flat response). In the case of an audio CD system the frequency response would need to be flat over the range of frequencies the CD contains, i.e. 20 Hz to 20 kHz.
Dynamic range is derived from the amplitude range between the loudest level that can be reproduced without producing distortion and the softest level that can be reproduced without being enveloped in noise. Dynamic range is the ratio between these two values and is usually expressed in decibels. In the case of an audio CD system the dynamic range needs to be at least 90 dB.
Signal-to-noise ratio gives an indication of the noise in the system. It is expressed as a ratio of the wanted signal power to the noise power in the system, and is usually expressed in decibels. A typical value for digital audio equipment is 100 dB.
As you will discover, the technologies used within the record industry have not always been capable of delivering sounds from systems with ideal characteristics for recording and playback. In fact, user convenience can be as important a consideration as the fidelity of the reproduced sound.