These areas of COMPRESSION and RARIFACTION can be measured and represented electronically as the waveforms you are more used to seeing in music production software.
It’s hard to imagine all the complicated sounds we hear each day being generated only by a vibrating column of air and even harder to see how a single squiggly line can represent them accurately. This is only an introduction to recording technology so we will keep things simple for now, but be aware that even the most complicated waveforms can be broken down into component sine waves. This is a a mathematical process called a FOURIER TRANSFORM
Thomas Edison invented the phonograph in 1877. It was improved upon by Alexander Graham Bell who introduced wax coated cylinders and called it a graphophone.
Remember the squiggly line of a waveform? Edison and Bell’s machines both worked by channelling the sound to be recorded into the recording horn. This would vibrate a diaphragm to which a stylus was attached. The stylus would etch the waveform into the recording medium (wax in Bell’s phonograph).It could then be played back by essentially reversing the operation and allowing the etched waveform to move the stylus, vibrate the diaphragm and vibrate air in the horn.
In 1889 Berliner & Suess invented the gramophone, that was able to carve sound wave-forms into flat discs, the forerunner of vinyl records.
By 1901 records could be mass produced first on SHELLAC and later on more flexible VINYL. As the 20th century progressed, Jazz was becoming popular and people could hear songs they wanted on the newly invented radio and also buy them on records. By the mid-1920s, electric recording using microphones (as opposed to recording horns) had dramatically increased the quality of recorded music
• Vinyl recordings have a warmth to them as they are a true analogue reproduction of the sound
• Their size meant that artwork could be creative and was much prized in the second half of the 20th century
• Modern day DJs like performing with vinyl as it lends itself to effects such as scratching and techniques such as beatmatching.
• Records are easily damaged by scratches on the surface or warping
• They can fluctuate in pitch on playback depending on the quality of the turntable motor (what exactly would cause this to affect the pitch?)
• They take up a lot of space!
By the middle of the 20th century, tape recording had been established as the main means of recording sound. Rather than a stylus, particles of ferric oxide are arranged by fluctuations in the magnetic field provided by the record head. These fluctuations represent the sound wave. By combining the play and record head, multitrack recording became possible and artists responded creatively.
• It was now possible to ‘drop-in’ on a recording and correct mistakes
• Tape could be reused
• Better quality sound than disc recording
• Tape hiss (needed to be removed by DOLBY and DBX)
• Again, pitch variation called wow and flutter was a problem
• Editing, although now possible, was very difficult and need razor blades to literally cut and splice tape segments together.
The image shown here is part of a waveform that has been measured periodically (the dots and steps being wherethe measurement has taken place). This is called sampling. These samples are stored on a computer and can be played back. This process is at the heart of digital recording.
Digital recording onto tape (to store information about the sound wave rather than the waveform itself) became commercially possible in the 1980s and common in the 90s. It was soon superseded though by use of hard drive recording. Software was developed that meant very professional sounding recordings could be made at home: Cubase, Logic and Garageband being examples. Sample based instruments (ROMplers) are frequently indistinguishable from the instruments that they are emulating and virtual synthesisers are flexible and powerful. Formats such as VST and AU plugins are used on PC and Mac based systems respectively