ADSR: Attack, Decay, Sustain, and Release are the four parameters found on a basic synthesizer envelope generator, and they match the physical attributes of naturally occurring sound. An envelope generator is sometimes called a transient generator. The Attack, Decay, and Release parameters are rate or time controls. Sustain is a level. When a key is pressed, the envelope generator will begin to rise to its full level at the rate set by the attack parameter, upon reaching peak level it will begin to fall at the rate set by the decay parameter to the level set by the sustain control. The envelope will remain at the sustain level as long as the key is held down. When a key is released, it will return to zero at the rate set by the release parameter.

Amplitude: A digital audio file’s sound levels or electrical signal levels. It refers to the height of a waveform—the greater a sound wave’s amplitude, the louder it sounds. Most software audio programs allow viewing the amplitude of the waveform for detailed editing.

Analog: An analog audio signal is represented by variations such as voltage speed or frequency and the strength of amplitude or volume of an electrical audio signal. The audio outputs from a computer’s soundcard or synthesizer are typically analog outputs even though the file being played is digital through a D/A converter. See D/A

(A/D) Analog to Digital Conversion: An electronic device that converts analog signals from a microphone or line level source into digital signals (digitizing or sampling them) so they can be stored to any number of storage media like hard drives, computer’s RAM chip, or processed in a sampler, digital signal processor or digital recording device.

Bit: Otherwise known as “Binary Digit,” it is a unit of digital information. A bit represents either an “on” of “off” value represented by a “0” or “1.” A bit is 1/8th of a byte.

BPM: Beats per minute. (example: a rap song with 130 bpm has more beats per minute than a classical song at 60 bpm)

Call and Response
The performance of alternate musical phrases by different soloists or groups, so that one seems to answer the other (known in art music as antiphony)
A musical device (sometimes an entire piece) in which a melody in one part fits with the same melody in another part even though the latter starts a few beats later. The device occurs in the type of song known as a round

Two or more notes played at the same time to create harmony. Often denoted by symbols eg, Cm F#7

Click track: Metronome pulse provided in software which assists musicians in keeping a consistent tempo.

Clipping: Distortion occurs when an amplifier is driven to play louder than its power supply allows and the result is clipping. This state can cause loudspeaker damage. It is of particular importance with digital audio recording because the clipped waveform contains an excess of high-frequency energy and the sound becomes hard and edgy. With analog linear recording it is standard to record as hot as possible; with digital non-linear recording, recording too hot will result in disastrous clipping.

Compression: Compression in audio recording means to reduce the dynamic range of a signal.

DAW: Digital Audio Workstation, such as LogicPro or Ableton Live. Software that is designed to be a complete recording, sequencing, editing and mixing tool on your computer for digital audio and usually MIDI too.

dB (Decibel): A unit used for measuring voltage, current or power. The decibel is often used to measure differences in sound pressure level or relative loudness.

Decoding: This is the process whereby information in a compressed digital audio file is read/expanded so that it can be converted from digital to analog to go to speakers so we can hear. There are software MP3 players that both decode and play MP3 files.

Delay: A common effect in a sampler or synthesizer [or effects] that mimics the time difference between the arrival of a direct sound and its audible first reflection.

(D/A) Digital to Analog Conversion: The process by which digital data (0’s and 1’s in binary computer language) is reconverted back to an analog (electrical) audio signal. This is how compact disk players play back CDs, and is the same means by which digital synthesizers and samplers play back their sounds through analog outputs such as speakers or headphones.

Dry: When recording audio, this refers to an audio signal which has had no effects added. The best practice is to record dry so one can audition a variety of effects in post production.

DSP Digital Signal Processing: DSP chips are found in sound cards, synthesizers, effects units, playback and speech synthesis, fax machines, modems, cellular phones, high-capacity hard disks and digital TVs. It is possible that the first DSP was used in the Speak & Spell game in the late 1970s from Texas Instruments. Typically, digital signal processing provides reverb or delay effects, loud speaker processing, EQ limiting and compression as well as feedback destroyers. Other audio uses are amplifiers that simulate concert halls and surround-sound effects for music and home theatre. See DSP and Merge.

High Pass Filter (HPF): A device which allows higher frequency data to be transmitted, rejecting lower frequencies, as used in Graphic EQ’s. For example, your HPF is set at 100Hz. This means everything below 100Hz to 20 Hz will not be as present in your audio signal. If you had a bass drum mic’d, you would not get any low end thump. See Low Pass Filter.

Interface: An audio interface such as  allows the computer to communicate with a microphone or line level device. A MIDI interface such as any USB-MIDI product, allows easy communication between a computer with USB port (or tablet with USB adapter) and a synthesizer or controller keyboard.

Loop: To repeat a sequencer pattern or portion of an audio sample repeatedly. The point to which the program returns, whether the beginning or some other point, is usually definable by the user.

Low-Pass Filter (LPF): Also called a High Cut Filter. A device which allows lower frequency data to be transmitted, rejecting higher frequencies. Most subwoofers have low-pass filters built in and many surround sound decoders have subwoofer outputs that have been low-pass filtered. See High Pass Filter.

MIDI: An acronym for the Musical Instrument Digital Interface, a standardized digital “language” that allows electronic musical instruments and computers to communicate with one another.

MIDI Cable: A special wire used to carry MIDI data; it has three shielded conductors connected to five-pin DIN plugs at both ends. It is not a MIDI interface by itself but some interfaces such as the M-Audio Midisport need MIDI cables to complete the communication between the computer and MIDI hardware.

MIDI Controller: This is a hardware device that outputs MIDI data . Other forms of controllers include drum, guitar, or wind controller. Real-time controllers are either continuous controllers (wheels, joysticks, sliders, foot pedals, breath controllers) or switch controllers (footswitches or other on-off devices). Many MIDI controllers do not have sounds but are used specifically to send MIDI data to another device such as a computer or a sound module.

Multi-Track: A recording device capable of recording several parallel parts or tracks which may then be mixed or re-recorded independently.

Oscillator: An electronic device capable of generating recurring waveforms at different frequencies for testing purposes, or a digital process used by a synthesizer to generate a waveform.

Overdubbing: Enables one or more of previously recorded tracks to be monitored while simultaneously recording one or more signals onto other tracks. This process can be repeated until the song or soundtrack has been built up. If a mistake is made, it is possible to recue the tape to the desired starting point and repeat the process until you have the best take on tape. See Dubbing.

Overtone: A whole-number multiple of the fundamental frequency of a tone. The overtones define the harmonic spectrum of a sound. See Partial.

PAM: Pulse Amplitude Modulation. In the first part of the A/D conversion, pulses occurring at the sampling frequency are modulated by an analog audio signal. See PCM.

Pitch: A continuous frequency over time.

Pitch Bend Wheel: A MIDI controller that can vary the pitch of a sound and allows notes to be bent up or down like when sequencing a sliding trombone sound for instance.

Portamento: A musical term referring to the gliding effect that allows a sound to change pitch at a gradual rate, rather than abruptly. This is an effect that can be assigned using an assignable MIDI controller knob on controller keyboards such as the Edirol PCR-30 or PCR-50.

Polyphony: Derivative from the Greek term meaning variety of tones, it is the number of notes which can be played simultaneously. Any synthesizer has a maximum polyphony which cannot be exceeded. If the polyphony is exceeded, MIDI data will drop out from MIDI channels used near the end of the sequence.

Quantization: A sequencing editing operation that can be used to correct timing mistakes, quantization forces all notes played to fall on the nearest beat specified.

Real-Time: In sequencing software there are generally two types of recording procedures, real-time; and step-time. Real-time is literally recorded in time that has not been adjusted, such as slowed down. Step-time is a recording method of inputting MIDI data that is sequentially laid down note-by-note, chord-by-chord and is particularly helpful for inputting data at one’s own pace.

Resolution: This is the accuracy with which an analog signal is represented by a digitized system. Although other factors affect accuracy of recording, the higher bit number used, the more accurately the amplitude of each sample can be measured.

Resonant Frequency: Any system has a resonance at some particular frequency and at that frequency, even a slight amount of energy can cause the system to vibrate. A stretched piano string, when plucked, will vibrate for a while at a certain fundamental frequency. Plucked again, it will again vibrate at that same frequency. This is its natural or resonant frequency. While this is the basis of musical instruments, it is usually undesirable in music-reproducing instruments like audio equipment or room acoustics.

Reverb: Acoustic ambience created by multiple reflections in a confined space. Also, a type of digital signal processing that produces a continuous wash of echoing sound, simulating an acoustic space such as a concert hall. Reverberation contains the some frequency components as the sound being processed, but no discrete echoes. See Echo, DSP or Delay.

Sampling Rate: This is the rate at which samples of a waveform are made and must be twice the highest frequency one wishes to capture. Commercial compact discs use a rate of 44,100 samples per second. (Se Nyquist Theory)

Sequencer: A MIDI sequencer, whether it is a software program or a stand-alone sequencer, arranges melodic and harmonic patterns in successive positions, sequentially. Storing MIDI information such as note-on and note-off events in memory and playing them back in the most fundamental task of a sequencer.

Slider: An input-device to manipulate audio or MIDI data; a typical use is to increase or decrease volume. Programs will have this as an on-screen image, like a button control that one can move with a mouse.

Sibilance: High frequency whistling or lisping sound that affects vocal recordings, due either to poor microphone technique or excessive equalization.

Sine wave: This is the most basic waveform which is a pure tone with no harmonics and consists of a single partial. The sine wave forms the basis of all complex, periodic sounds.

Square Wave: A symmetrical rectangular waveform which contain a series of odd harmonics.

Subtractive Synthesis: The process of creating a new sound by filtering and shaping a raw, harmonically complex waveform.

Synthesizer: A synthesizer is a device driven by a microprocessor which contains a programmable chip. Originally, a synthesizer produced an audio signal by the direct manipulation of electrical signals. Now MIDI sound-generating circuitry utilizes mathematical functions which alter a stream of digital numbers.

Tempo: The rate of speed at which a musical composition proceeds (i.e. the beat). Usually uses a quarter note as the timing reference.

Timbre: The quality of a sound that distinguishes it from other sounds of the same pitch and volume. It is the distinctive tone color of an instrument or a singing voice.

User Interface: also called a “UI” or simply an “interface,” is the means in which a person controls a software application or hardware device. A good user interface provides a “user-friendly” experience, allowing the user to interact with the software or hardware in a natural and intuitive way.

Vocoder: A digital signal processor that applies a filter on a sound based on the frequency characteristics of a second sound. By taking the spectral content of a human voice and imposing it on a musical instrument, talking instrument effects can be created. There are plug-ins available with this effect, such as Native Instruments Vokator.