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Music Technology & Home Recording Glossary I

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I/O: The part of a system that handles inputs and outputs, usually in the digital domain.

IC: Integrated Circuit.

ID3 - small file that can be attached to an MP3 that contains album, artist, track, and other info.

Imaging: This is an audio listening term and refers to the ability of a speaker to position sounds precisely in space. A good stereo system can provide a stereo image that has width, depth and height. The best imaging systems will define a nearly holographic recreation of the original sound.

Impedance: - At it most general electronic level, impedance is the amount of resistance and / or reactance offered by an electronic circuit or device to the (AC) current which flows through it. It is commonly represented by the mathematical symbol "Z", and is measured in Ohms. Some people may have had an unwelcome brush with the laws of impedance when (usually drunk at a party!) they attempt to wire several speakers to each channel of their amplifier, then witness the scene of expensive electronic carnage which usually follows! A measure of the AC (alternating current) resistance to the flow of electrical or acoustic energy. In electronics it is measured in Ohms.

INDUCTOR: Reactive component that presents an increasing impedance with frequency.

Infrasonic: - Sound frequencies which are below the lowest frequency of human hearing (20 Hz). See also Ultrasonic.

Inharmonic A partial or sinewave component of a sound which bears no simple arithmetic relationship to any other partial in the sound. See also Harmonic.

INITIALISE: To automatically restore a piece of equipment to its factory default settings.

Initialization: Typically used with synthesizers, it is a procedure which places default values or factory settings into some or all parameters. It is especially helpful when clearing out a multitude of previously sent MIDI messages.

Insert Point: - A connection which permits the insertion of an external signal processing device (reverb, compressor, gate, eq etc) into the signal path. A connector that allows an external processor to be patched into a signal path so that the signal now flows through the external processor.

Insulator: - Any material which is very poor at conducting an electrical current (eg rubber, plastics etc). Opposite of "conductor". See also resistance.

Integrated Circuit (IC): - Originally conceived by UK Ministry of Defence scientist, Geoffrey Dummer an integrated circuit is a series of transistors (along with capacitors, resistors etc), working together to perform some task within one discrete unit. The first working model of an IC was patented by Jack Kilby of Texas Instruments as a "Solid Circuit" using Germanium as a semiconductor. Slightly later (1961), a more advanced device, utilzing silicon as the semiconductive material, and known at the time as a "Unitary Circuit" (Later "Integrated"), was patented by Kenneth (Intel) Noyce when he was working at Fairchild Semiconductor. Intel's Ted Hoff later took IC's to an extreme, when he developed a device known as a "microprocessor", (the Intel 4044).

Interactive sequencer: A computer-based sequencer that directly interfaces with MIDI controllers and sequenced MIDI files to internally generate MIDI prformance data according to a computer algorithm.

Interface: An audio interface such as Echo Audio’s Layla allows the computer to communicate with a microphone or line level device. A MIDI interface such as any Edirol USB MIDI product, allows communication between the computer and a synthesizer or controller keyboard.

INTERMITTENT: Usually describes a fault that only appears occasionally.

INTERMODULATION DISTORTION: A form of distortion that introduces frequencies not present in the original signal. These are invariably based on the sum and difference products of the original frequencies.

Internal sequencer: A sequencer designed into an electronic instrument that directly interfaces with the instrument's keyboard and voice structure.

International Standard Recording Code (ISRC): THE international identification system for sound and music video recordings. Each ISRC is a unique and permanent identifier for a specific recording and can be permanently encoded into a product. The encoded ISRC can also be used in automated data processing systems to identify the owners and other participants in sound and music video recordings. This associated metadata is essential for distribution of royalty payments.

IPS": - Acronym of Inches Per Second, a measurement of the speed that a tape travels when it is playing.

IRQ" (Interrupt request): - An Interrupt Request is a message, usually sent from a hardware device within/ connected to your computer (eg Hard Disk, printer etc) via a dedicated line to the Central Processing Unit (CPU) of your system. In modern "plug and play" systems each dedicated IRQ line is automatically assigned a number, however in older systems this had to be set manually by the user. IBM standard PC's have a maximum of 15 IRQ lines, which work on a priority basis, depending on the relative importance of the Interrupt. so that an Interrupt Request with a high priority may interrupt one with a lower priority, and one with a very high priority may override both of them! For reference, heres a list (below) of the standard IRQ configuration for a PC standard computer. 00) - System Timer . . . 01) - Keyboard . . . 02) - Cascade Controller / 2nd PIC . . . 03) - COM's 2 & 4 . . . 04) - COM's 1 & 4 . . . 05) - Sound / Parallel Port 2 . . . 06) - Floppy Disk . . . 07) - Parallel Port 1 . . . 08) - Real Time Clock . . . 09) - Redirected IRQ2 / Network Available / Open . . . 10) - Open . . . 11) - SCSI / Video / Open . . . 12) - PS2 / Open . . . 13) - Co Processor . . . 14) - Primary Hard Disk (Master) / Hard Disk Controller / Open . . . 15) - Secondary Hard Disk (Slave) / Open . It should be noted that IRQ's 00, 01, 02, 08 and 13 Should always remain static, and never be removed or shared with any other devices, whereas the others may possibly be reconfigured or removed.

Isopropyl Alcohol: - Best kind of alcohol to use for the cleaning of tape heads and other metallic devices used in audio.

E-Book - An Annotated Compendium of Old Time American Songs by James Alverson III