## 3 Artificial Audio Effect Technologies
### Sound Recording and Reproduction Technology
The pitch is dependent on the relative velocity of the tape to the multiple rotary head. If the head rotates in the direction of the tape movement, the relative speed is lowered, which results in a lower pitch. Moving the playback head in the opposite direction increases the speed at which the information from the tape is read, thus raising the pitch. Multiplicative scanning results in lengthening of the duration; likewise, shortening is achieved by skipping portions of the tape at equal intervals. This development is significant, since it presents an early example of dissociating pitch from duration, the basis for many effects in use today based on _time stretching_ and _pitch shifting_ as opposed to simple _variable speed replay_. Furthermore, these developments constitute early examples of granulation. Employing granulation as a compositional tool has been pioneered by [PERSON] in Metastasis (1954), Concret PH (1958), and Analogique A-B (1959), the latter being described by [PERSON] [77]. For the piece _Analogue B_ (1959), he recorded sinusoids produced by an analogue tone generator and scattered grains onto time-grids after cutting the tones into short fragments. [PERSON] proposed the idea that every sound, including musical recordings can be represented as a combination of elementary sounds. More novel devices were developed at GRM, such as a three-head tape recorder for simultaneous playback and the _Morphophone_ featuring ten heads for the creation of echo effects and looping capabilities. Soon, a number of standard techniques for the creation of tape music were established. Splicing and cutting of tape in various manners, for instance, created different effects of the transition from one sound to another [78]. Tape delay (see Figure 4), manipulation of playback speed, and tape reversal became common practice. Although experimental composers and researchers within the academic framework continued to innovate in the audio effects domain, the emerging technologies became increasingly important in the production of popular music post World War II. In 1941, [PERSON] started producing repetition effects with disks and multiple playback pickups [16]. Towards the end of the decade, he made extensive use of multitrack recording-based effects and pioneered several techniques in the creation of his music [79]. By recording instruments with a tape recorder while playing back previously recorded tapes, he produced his music by layering the instruments one after the other. Here, the playback was sometimes played back at double speed, which as a result also transposes the audio material by one octave and changes the timbre due to the shifted spectrum. Another technique of [PERSON] was to play back, for instance, a rhythm guitar at half speed while recording a guitar solo on top of it. In the final piece, the combined tracks would be played at normal speed again. This resulted in the solo being played tremendously fast. Indeed, due to the novelty of these techniques, listeners at the time were often clueless as to how this music could have been produced. [PERSON] himself would often give intentionally misleading explanations for his sound. He attributed the high-pitched guitar sound to guitars of small sizes pitched one octave higher and claimed to create the chorus-like effects on vocal and guitar tracks with a fictional device he called the _Les Paulverizer_ capable of multiplying instruments and vocals. In reality, however, the chorus was a result of his multitracking technique of recording several takes on top of each other. However, confronted with the dilemma that it was impossible to reproduce his studio sound in a live performance setting, around 1956, [PERSON] would indeed build a little black box to be mounted on his guitar, referred to by him as the _[PERSON]_ (see Figure 5). This device allowed him to control a tape recorder while playing in order to record and playback several tracks while on stage. Figure 4: Traditional tape echo: the signal picked up by the playback head feeds back to the record head.