Important subsequent developments: wide use Above, we have discussed the wide range of sound-generating processes developed over the decades as part of

computed sound. Below, we will discuss how the various types of sound generation identified became widely used in the instrumental control of musical sound. This happened based on many successive implementations of the basic pairing of electronic digital computer and electric loudspeaker.

The development of loudspeakers and related amplification technologies continued, leading to better-quality sound reproduction across many form factors. This ranged from sound systems for large crowds, via home stereo systems, to lightweight headphones used with mobile cassette players. Historically, these developments, begun before the introduction of electronic digital computers, continued to evolve independently. In practice, this meant that widespread use of specific forms of computed sound usually was fundamentally limited not by the availability of suitable loudspeaker technology, but by the state of ongoing developments in devices for electronic information processing.

These developments first of all included the digital encoding of information, itself. This provided a fundamental representation shared increasingly widely across many different types of devices. Also, implementations of this were of an increasingly high reliability, with devices retaining or changing their state reliably over many iterations

of information processing. These iterations, in turn, were of ever shorter duration, for ever faster computing and information processing. Also, ever more information became subject to automatic processing, with increasing digital memory sizes giving ever greater storage per device. Between devices, communication over distance increasingly became possible, and at increasing transmission speeds. Devices implementing a given technical level of the previously listed characteristics became ever smaller in size and ever cheaper to obtain commercially. Due to the development and implementation of user-friendly human-machine interfaces, such as the GUIs discussed in Section 1.2.3, devices also became increasingly easy to operate.

As the state of these general developments in devices for electronic information processing allowed it, wide use in the instrumental control of musical sound became a reality for many of the new types of sound-generating processes developed as part of computed sound. For example, faster processing enabled the professional and live use of sampling, as a standard technique that became heavily used in the creation of popular music. Faster processing also enabled the live use of various types of parametrized waveform synthesis and physical modeling, with digital synthesizers based on frequency modulation and waveguide modeling becoming commercially available. Sequencing, too, became widely used professionally, especially in combination with sampling, e.g. for assembling percussion-like sound fragments into rhythmic musical sound. In general, it is safe to say that the combination of sequencing and sampling has had a great impact both on how much of popular music is created, and on how it sounds.

In the further processing of musical sound, many types of amplitude-based signal processing and spectrum-based operations became part of standard toolkits for filtering, mixing, equalizing and mastering sound signals. As practically usable memory sizes increased, this was combined with reliable and high-resolution digital implementations of professional multitrack sound recording and editing. Various forms of sequencing and score editing became integrated as much of music recording studio technology in general became digital. Since costs lowered continuously, most of these technologies also became available to, and widely used by, amateurs. Here, low cost often was the more decisive advantage of computed sound, for example where sampling became used to mimick the sound of existing acoustic instruments. Many digital keyboard devices were built and sold based on their ability to provide a cheap imitation of the instrumental control and musical sound of acoustic pianos.

Of course, computed sound also became widely used in the playback of musical sound. Here too, increasing processing speeds, storage sizes and reliability enabled the practical use of high-quality digital representations of sound. The physical media and playback technology of the Compact Disc (CD) consumer format became a very successful example of this. In general, digital technology eliminated sound degradation on repeated playback, copying and storage as a practical problem. The later MP3 format for digitally stored sound became a good example both of the flexibility resulting from the basic digital representation shared across devices, and of the increasing possibility of communication between devices, as many people began to use the format to obtain and distribute musical sound across a wide variety of devices, all

connected over the internet. Into the 21st _{century, this also began to include small,} cheap and easy-to-use handheld personal computers, wirelessly connected to the internet. Due to the wide availability of such devices, which give instant access to sound stored in large memories incorporated locally or at remote machines, many people in many parts of the world have quickly grown accustomed to the possibility of listening, anywhere in their daily surroundings, at any time, to the high-quality playback of any musical sound out of a very wide range of choices.

1.4.4 Reflection: Theoretical and practical fundamentals for computed sound