Welcome to this tutorial on air, electrical and magnetic pressure sound waves.

In sound recording, soundwaves may be manipulated and/or stored in 4 forms ...

- Changing air pressure energy
- Changing electrical pressure energy
- Changing magnetic pressure energy
- Digital

Caption - Air pressure sound waves

Sound in the air takes the form of changing air pressure energy. This energy is measured in decibels. Decibels is covered in a separate video tutorial.

Caption - Electrical pressure sound waves

In order to amplify or record sound we must first convert it into electrical pressure. Electrical pressure is expressed in volts. The conversion is achieved by means of a transducer, in the form of a microphone. A transducer is a device for converting one form of energy into another, so a microphone converts air pressure sound waves into electrical pressure sound waves.

Microphones produce a very quiet electrical pressure sound wave signal which must be amplified by a microphone pre-amplifier up to line level before it can be processed or sent to be recorded.

Caption - Magnetic pressure sound waves

In it's electrical form, it is extremely difficult to record, or store, sound. A tape recorder is a device which can convert an electrical pressure soundwave into magnetic pressure which is then stored in the oxide of a piece of moving magnetic tape. In this case the conversion is handled by a transducer called a tape head. Magnetic pressure is measured in flux.

Caption - Digital sound
In the case of digital, the analogy of "pressure" breaks down because the pattern of changing pressure is converted into a mathematical description of the wave in the form of a binary data stream. Although this data stream is itself represented by an electrical signal in the form of a simple on off pulse wave , the shape of the wave is in no way analagous to the sound wave it represents.

However, like analogue electrical sound waves, this digital pulse wave can travel down electrical cables, but unlike analogue it can be recorded to a wide variety of physical formats including linear tape, solid state memory, optical media, and magnetic hard disc drives.

Caption - Thanks for watching

The script for this video, with accompanying images, can be found at projectstudiohandbook.com 

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