see Solid-state Drive.

see Stereo Recording Angle

A symmetrical rectangular waveform. Square waves contain a series of odd harmonics.

Song Position Pointer (MIDI).

Sound Pressure Level. A measure of the intensity of an acoustic sound wave. Normally specified in terms of Pascals for an absolute value, or relative to the typical sensitivity of human hearing. One Pascal is 94dB SPL, or to relate it to atmospheric pressures, 0.00001 Bar or 0.000145psi!

Unwanted sound picked up by microphones on one instrument from other nearby instruments.

An accurate loudspeaker intended for critical sound auditioning purposes.

Sony/Philips Digital InterFace. Pronounced either ‘S-peedif’ or ‘Spudif’. A stereo or dual-channel self-clocking digital interfacing standard employed by Sony and Philips in consumer digital hi-fi products. The S/PDIF signal is essentially identical in data format to the professional AES3 interface, and is available as either an unbalanced electrical interface (using phono connectors and 75ohm coaxial cable), or as an optical interface called TOSlink.

A means of arranging two or more microphone capsules such that they receive sound waves from different directions at different times - these timing differences being used to convey information about the relatice directions of those sound sources. The technique is usually used with omnidirectional microphones, although directional mics can also be employed. The best known form of spaced array is the Decca Tree. Mono-compatibility is often reduced because the timing differences between channels often results in comb-filtering colouration when the channels are summed to mono.

The use of materials and construction techniques with the aim of preventing unwanted sound from entering or leaving a room.