A brief history of computer sound

In the 1940s, the transistor allowed the construction of computers that were sophisticated for their time. A computer is unique among machines in that its function is not inherent in its structure, but rather determined by a set of instructions entered into it. It made sense, therefore, that someone would develop a program that would allow computers to not only store and transmit music, but also to compose and perform it. Performance is facilitated by the fact that computers can be interfaced (connected by translating circuits) to other kinds of electronic devices such as recording devices, synthesizers, audio -visual appliances etc.

In 1957, Max V. Mathews of AT&T Bell Laboratories became the first person to program a computer to make musical sounds, but most early computer music was of poor quality because it was created by computer programmers rather than by musicians who had a working knowledge of music and sound. Early experiments in computer-generated sound were made in the form of collaborations between computer experts or engineers, and computer-friendly musicians. This phenomenon led, in the 1970s, to the establishment of music research centres that were dedicated to the advancement of research in the field of computer music. These research centres included the Institut de Recherche et Coordination d"Acoustique et Musique (IRCAM ) in France, the Center for Music Experiment and Related Research (now the Center for Research in Computing and the Arts) at the University of California at San Diego, the Center for Computer Research in Music and Acoustics (CCRMA) at Stanford University and the Electronic Music Studio at the Massachusetts Institute of Technology (MIT).[2]

By the 1980s, the technology that was developed for creating computer music was applied to the recording industry, and digital sound recording became widespread. The commercial introduction of the personal computer, which were a great improvement on the giant computers of previous decades, brought about the design of user-friendly interfaces which were aimed at non-specialists in music. One such interface which was developed to fulfil the needs of musicians was MIDI (Musical Instrument Digital Interface).

Over the past ten years, the desktop computer has developed from a device capable of handling small amounts of text, games and basic programs, to a device which is capable of processing full-colour broadcast-quality video, hours of CD -quality audio in real time, and complete volumes of text and graphics to publishing standard. This has been made possible by the development of the digital microchip - hundreds of thousands of transistors etched onto thin layers of crystalline silicon. The microchip has allowed the home computer to become a powerful music-making machine, capable of recording, manipulating and storing digital audio data, and interpreting and playing back audio from the Internet in a wide variety MS of audio file formats. The two leading personal computer systems, Apple Macintosh OS (Operating System) and MS-DOS (Microsoft Disc Operating System)/Windows for IBM PC, have developed new programs and file formats while allowing compatibility with older software. It is this compatibility and standardisation, rather than technical innovation, which establishes systems as market leaders.

Personal computers can play two different kinds of sound or music - synthesized sound as MIDI and sound data as digital audio . A brief definition of the differences between the two kinds follows.

digital audio

While analogue sound is represented as a time-continuous format (i.e. a waveform), digital audio is the name given to sound or audio data that has been converted into a time-discrete numerical format, which is stored as a series of zeroes and ones known as binary code . Binary code is based on the use of transistors in the original computers that were developed. The binary digits, 1 and 0, each represent a single switch which is either on (1) or off (0), and which can be rapidly controlled by electronic control signals. A single binary digit is known as a bit and is the smallest unit of computer data. An interconnected network of transistors stores and processes computerised information as a series of binary digits which make up a single alpha-numeric character (e.g. a-z, A-Z, 0-9 etc) or a computer command (print, load, copy etc).

Analogue sound, on the other hand, is stored and/or carried by one of four alternate means -

Digital audio is stored digitally as binary information that can then be manipulated just like any other computer data at high speed by a computer, a process that is known as digital signal processing (DSP). The advantages of digital signal processing are numerous - errors in sound can be corrected, even after recording, using powerful error-correction software. Unlike analogue sound, the sound quality of digital audio is independent of the medium on which it is stored or transmitted, and is stored non-linearly, which means that it can be transmitted discontinually if required, as long as the data is re-assembled in the correct sequence at the user end.

Of utmost importance to the music industry, a digital signal does not degrade through copying, provided that the signal is copied digitally - i.e. the data is copied rather than the analogue output of the digital system.

MIDI (Musical Instrument Digital Interface)

Though a digital interface with a defined protocol, MIDI is not a digital audio interface, but rather exists for the purpose of interconnecting electronic musical instruments and their associated devices (such as effects and mixers). MIDI allows electronic instruments to be controlled externally, either by a master keyboard or by a computer, and carries control information relating to pitch, duration, velocity etc. than binary sound data.

On a multimedia computer, MIDI files produce music through the PC's internal soundcard, but do not usually store real-world digital audio sounds such as the human voice, except in cases where sound is sampled in short bursts for looping purposes. As a result, MIDI files do not contain vast amounts of data and therefore consume less disk space than digital audio.

One advantage of digital audio over MIDI is that since PC hardware monitors audio input on a regular basis (i.e. at the chosen sample rate ), information is constantly transferred to the disk - regardless of whether there is an input signal present or not. MIDI data arrives at the disk in a far less constant manner - there will be no data arriving in quiet passages, while note-heavy passages carrying vast amounts of MIDI control data causes the computer's processor to work harder.