A piece of software that handles communications between the main program and a hardware peripheral, such as a soundcard, printer or scanner. Also a term used to refer to a physical loudspeaker drive unit - eg bass driver.

A physical device designed to generate an acoustic sound wave in response to an electrical input signal. Drive units can be designed to reproduce almost the full audio spectrum, but most are optimised to reproduce a restricted portion, such as a bass unit (woofer) or high-frequency unit (tweeter). A range of technologies are employed, with most being moving-coil units, but ribbon and electrostatic drive units also exist, each with a different balance of advantages and disadvantages. Also known as a ‘driver’.

Digital Signal Processor. A powerful microchip used to process digital signals.

Also known as a Reussen screen. The signal-carrying wires in a microphone cable are protected from external electrostatic and RF interference by a ‘screen’ which is a surrounding conductor connected to earth or ground. The Reussen screen is a specific form of cable screen, comprising two overlapping and counter-wound layers which are unlikely to ‘open up’ if the cable is bent, yet remain highly flexible

A method for removing or attenuating the noise component of a recording or transmission system, in which the signal is pre-conditioned in a specific way which is reversed on playback. Most analogue noise-reduction systems are of the double-ended type, such as the Dolby and DBX systems.

A specific shape of drive unit diaphragm intended to push and pull the air to create acoustic sound waves. Most tweeters use dome-shaped diaphragms which are driven around the circumference by the drive unit’s motor system. ‘Soft-domes’ are made of a fabric - often silk - while metal domes are constructed from a light metal like aluminium, or some form of metal alloy.

Disk Operating System. Part of the operating system of PC and PC compatible computers

Invented by Bang & Olufsen and licensed to Dolby. HX (often marketed as HX Pro) stands for 'Headroom eXtension' and it is a record-processing system used on some analogue open-reel and cassette tape-recorders (there is no complementary replay processing). Dolby HX Pro varies the amount of recording bias depending on the strength of high-frequencies in the audio signal itself to avoid magnetic saturation and over-biasing. This makes it possible to record with a higher overall fluxivity on the tape.

Dolby’s surround sound systems started with an analogue 4:2:4 phase-matrix system with a very elaborate active-steering decoder called ProLogic, before moving into the digital realm with Dolby Digital, Dolby Digital Plus, Dolby True HD, and others.

A manufacturer of analogue and digital audio equipment in the fields of tape noise-reduction systems and cinema and domestic surround-sound equipment. Dolby’s noise-reduction systems included types B, C and S for domestic and semi-professional machines, and types A and SR for professional machines. Recordings made using one of these systems must also be replayed via the same system. These systems varied in complexity and effectiveness, but essentially they all employed the principlals of spectral noise-masking in ever-more complex ways using multiband encode/decode processing to raise low-level signals during recording, while reversing the process during playback.