AUDIO+TERMS

==Below is a listing of many digital audio terms. Some key terms you should know, and should be able to identify in various recording applications, include: waveform, stereo, mono, amplitude, frequency, sample, playhead, input volume, VU meter, transport controls, timeline, automating volume, AIFF, MP3, 44,100 hz. (sampling rate).==

Digital Audio Glossary
**AIFF –** Audio Interchange File Format. Format for storing sampled sound developed by Apple and used on Macintosh computers. AIFF is uncompressed audio; fidelity is high. File size is large, about 10 MB (megabyte) for every minute of recorded audio. These files have the extension .aif or .aiff. **Amplitude** – The strength of a (sound) signal. ** Analog ** – In electronic recording, a system that allows the voltage of the signal to vary (up and down) continuously with the sound pressure (from the microphone or going to a speaker). **Audio Interface** – Using an analog-to-digital converter (ADC), allows a signal recorded with a microphone to be sent to recording software on a personal computer. **Audio range** – For humans, about 20 through 20,000 hz. **Auto-Tune** – Popular audio processing software (by Antares Audio Technologies) and DAW plug-in that can tune recorded vocal and instrumental pitches to the nearest semitone. It is also used to distort human vocals, making them sound “metallic” or “robotic.” The term “auto-tune” has come to be used as a verb when referring to its application to recordings (i.e. “Her voice has been auto-tuned.”) **Break Points** – With audio recording software, a point of articulation entered along a track’s automation line. Each breakpoint allows for an automated change of direction in volume, pan position, or some other parameter during playback. **Chorus** – An electronic effect that modifies a signal to emulate a section sound (i.e. string section or chorus) by replicating/detuning and more. **Clipping** – When a device cannot accommodate a signal’s maximum voltage or current requirements (i.e. the amplifier output is overloaded or its input is overdriven). So named because the waveform appears to have a flat top. **Compression –** Compression squashes the high peaks of an audio signal, reducing the overall dynamic range. Compression is often used in combination with gain to raise the strength of the overall signal. **Decibel** - Commonly used as a measure sound intensity or power, it is technically a //ratio// representing the comparison of two power values. Zero dB is at the threshold of hearing. Comparatively, a quiet whisper is around 30 dB, normal speech is 60 dB, a loud rock concert about 100 dB, and a jet airplane taking off is about 120 dB (and painful). The decibel scale is logarithmic rather than linear. A sound that is ten times more intense represents a10 dB change, 100 times more intense is 20 dB, and 1000 times more intense is 30 dB, etc. Of course, distance and frequency (since we aren’t equally sensitive in every frequency range) greatly affect human perception of loudness. **Digital Audio** – Representing sound in discrete (steps, rather than continuously as in “analog”) values. **Digital Audio Workstation (DAW)** – The term Digital Audio Workstation, or DAW, refers to a single software application that allows for many aspects multi-part music production, including most notably: audio and MIDI recording, editing, and mixing; applying digital signal processing effects; and use of audio and MIDI loops. It is assumed that a DAW system has accompanying hardware for translating an audio signal from the analog domain (i.e. voice sung into a microphone, guitar output from a patch cord, etc.) into the digital domain. This sort of analog-to-digital converter might be as uncomplicated as a simple USB (“plug-and-play”) microphone or as sophisticated as a Firewire audio interface with inputs for multiple XLR (typical microphone) and ¼” phone (typical guitar, synth keyboard) plugs. The most ubiquitous DAW application in music studios around the world is undisputable ProTools, but there are many other professional (Mac OSX: Logic, Digital Performer. Windows: SONAR) and entry-level (Mac OSX: GarageBand. Windows: Mixcraft) programs that serve school programs well. **Digital Signal Processing (DSP)** – DSP is defined as the manipulation and modification of signals in the digital domain. Today’s DSP enhancements are a carry-over from analog features. A distinction is made between effects and processors. Effects are added to the original signal, while a process changes the original signal. Examples of effects include reverb, echo, delay, chorus, phasing, flanging, and pitch shifting. Examples of processors include equalizers (EQ), gates, compressors. In the digital realm, the distinction between effects and processors is blurred since these alterations can be made “non-destructively.” A digital audio stream is in essence a series of numeric values representing the amplitudes of successive samples. Applying digital effects to the signal consists of running the series of numbers through an equation (as opposed to an analog effects processor unit). **Dynamic Range** – Comparison of the softest to the loudest sound of a system. A full orchestra may have a dynamic range of 90 dB. **Envelope** – The shape of a sound, usually described in stages: Attach, Decay, Sustain, Release (ADSR). Better synthesizers keyboards allow the user to edit the stages of the envelope to alter the sound. ** Equalizer (EQ) ** – EQ allows the user to amplify or attenuate various frequency regions, sometimes called “bands” (i.e. 100 through 1000 hertz). Multiband EQ allows the user to set the levels for each of the defined bands. EX: A thin vocal sound can be filled out by boosting the bass frequency bands and pulling back a bit the extreme high frequencies. **Feedback** – Unwanted, self-referencing loop between a microphone and a speaker in the same system. Either the volume for the amplifier is set too high, or the microphone is placed too close to the amp. Also called regeneration. **Filter** – In digital recording, a process which rejects certain frequency components of a signal. By eliminating some of the spectral content, you can alter the timbre subtly or greatly. Filters may be low pass (allows only frequencies below a threshold), high pass (allows frequencies above a threshold), or band pass (allows frequencies between a low and high limit). Depending on the software, you may be able to control parameters such as the filter's center frequency and the range of the area to be attenuated (bandwidth). **Flange** – This effect produces a swooshing sound, originally accomplished by splitting the signal into two identical versions; applying a constantly varying, short delay (usually 2 to 15 ms) to the signal; and mixing the altered signal with the original. The name comes from the act of pressing a finger against the flange of a reel-to-reel tape deck's supply reel to slow it down, causing the delayed signal to be out of phase with the original. **Frequency** – Measure of the rate of a periodic (regular rate) vibration, in hertz (cycles per second). The frequency of a sound is inversely proportional to its //period// (the time it takes to complete a single cycle of the sound wave; see below). That is, F = 1/P, where F is frequency and P is period. EX: If it takes .01 seconds (1/100th of a second) for one complete cycle of the waveform to occur, then the frequency is 100 hertz (1/.01). **Frequency Response** – Description of the way the gain of a system responds to a frequency stimulus. **Fundamental** – The lowest, and with acoustic sounds the dominant, frequency heard in the spectrum of a particular sound. **Gain** – The amount of increase in the power of a signal by an amplifier. **Harmonic Series** – The fundamental and all overtones of a sound. All the members of this series are called //partials//. **Hertz** – Cycles per second, abbreviated “hz.” **Loops** – Short, musical gestures whose repetition is facilitated by music production software. Most loops involve recordings (audio) or sequences (programmed MIDI) of rhythm instruments (percussion, bass, guitar, etc.) performing some groove element. The tempo and pitch (if applicable) of loops may be easily adjusted, independent of one another, using the host music production software. **Microphone** – An electro-acoustical device which delivers an electric signal when actuated by a sound. A microphone consists of an acoustic system which supplies mechanical energy to a transducer, which is then converted into electrical energy. There are many types/variables of microphones: dynamic (close range), compressor (more detail, further away), omni-directional (equal signal from any angle), uni-directional (cardioid and super cardioid, long-range), those requiring phantom power and those not (need some extra pre-amplification, usually initiated in mixer or audio interface). Other parameters such as frequency response and dynamic range have practical recording applications. **MIDI** – Musical Instrument Digital Interface. The hardware and software standard protocol developed in 1984 which allows musical instruments, personal computers, and music software to interact with one another. **Millisecond** – One thousandth of a second (.001 seconds). **Mixer** – A device that allows several signals to be combined into one signal. Each source signal (i.e. ¼” phone or XLR mic) is assigned a channel (or channels), usually with independent control for volume level, pan position, and effects levels. The output, a stereo mix, is usually sent to monitor speakers, headphones, and/or a recording device. **Monaural (Mono)** – Recording to a single channel. **MP3 –** Short for “MPEG-1 Audio Layer 3” (where MPEG is the Moving Picture Experts Group). MP3 is a sophisticated compression scheme for digital audio. Audio converted to MP3 remains very faithful to the original sound at about a tenth of the file size, about 1 MB (megabyte) for every minute of recorded audio. **Noise** – Sounds that cause random vibratory motion of molecules. **Normalize** – This procedure raises the level of the highest peak to 0 dB, and then raises all other parts of the signal by the same proportion. Normalizing is useful when a signal has been recorded at too low a level or when the volume is inconsistent throughout. **Overtones** – Integer multiples of the frequency of the fundamental. **Pan** – Left-right position of the stereo image. **Partials** – The members of a harmonic series; numbered in ascending order from the fundamental (1) on up through the overtone series. **Period** – Time it takes for one complete cycle of a periodic (regular rate) vibration. The period is inversely proportional to the frequency. That is, P = 1/F, where P is period and F is frequency. EX: Take a sound with a frequency of 100 hertz. It takes 1/100 seconds (.01 secs.) for one complete cycle of the waveform to occur. **Pitch Shifting** – Operation applied to an audio signal which raises or lowers the pitch (frequency) without affecting durations of recorded events (i.e. rhythm or length of file). Likewise, you can shorten or lengthen audio without changing its frequency. Normally this process leaves certain timbral artifacts (altered spectral content). **Phone Jack** – The straight plug found at the end of guitar cables, but also used to connect computer audio components. Phone jacks may be mono (one black insulator band on the plug) or stereo (two black insulator bands on the plug) and come in 1/4” or 1/8” sizes. **Pop Filter (or Pop Screen)** – A Screen, usually attached to a microphone stand, that stands between the microphone and a singer’s mouth to eliminate the “popping” that results from spoken or sung “plosives” such as the hard “p” at the beginning of the word “pop.” **Quantization Error** – Also called digital noise. The wide band noise resulting from the rounding of sample values in digital recording. When the rounding is slight, quantizing noise is virtually imperceptible. **Quantizing (re: digital audio recording)** – In digital recording, rounding the actual value (analog) of an amplitude measure to the nearest value represented by the digital system (due to its bit resolution). **Ramp** – A straight-line change in volume applied to automated fades (fade in, fade out). **Ratio** – A comparison of two values, often expressed as “1:2”, or as a fraction (i.e. “1/2”), or even as a decimal (i.e. “.5”). **RCA Jack** – Found on the end of many cables used with stereo equipment, usually red and white for stereo left and right. The “male” connector is a plug with a sleeve and connects to the “female” port, a knob with hole. **Resolution** – In digital recording, the number of bits (or bytes) allocated to store each sample. 1 bit (2 1 ) only allows for 2 amplitude positions (on or off). 2 bits (2 2 ) allows for 4 different amplitude positions. 8 bit systems (2 8 ) allow for 256 different amplitude values, and so on. **Reverb –** Short for “reverberation.” Reverb is the decaying residual sound that remains after a sound occurs and is created by the sound's multiple reflections off of surfaces in an acoustical space. The time of reverberation is defined as the time it takes for the sound pressure level to decay to 1/1,000,000th (one millionth) of its former value. This is a 60 dB reduction. Adding digital reverb can liven up samples and alter the virtual acoustics of the space within which your digital audio exists, creating anything from subtle room ambience to the rich echo of a large stadium. Echo is a DSP effect similar to reverb. **Sample** – In the strictest sense of the word, a sample is a digital record of the amplitude (strength) of a sound signal at a discrete point in time. Some use the term to mean a series of many consecutive samples, which constitutes a short digital recording of a note or musical phrase. **Sampling** – Short, note-length recording of an instrument or other sound captured and played back in various ways by electronic instruments (i.e. keyboards, etc.) and sound modules. Often the middle of a sample (after the attack, but before the release) is looped or cycled according to vary the playback duration. **Sampling Rate** – In digital recording, the time interval between recording amplitude readings (samples). For compact discs, the sampling rate is 44.1 khz. **Shareware** – Low cost software application available for download from the Internet. **Sibilance** – Excessive loudness of vocal sibilants (such as the “sss” and “sh” sound). A De-esser is used to reduce this unwanted effect. **Signal-to-Noise Ratio** – Comparison (expressed in decibels) of the level of a signal to the level of inherent noise in the system. If a signal is 50 dB above the low-level noise, we say its S/N ratio is 50 dB. **Spectrum** – The sum of all the frequencies heard simultaneously in a (usually **Stereo** – Two channel (left and right) recording.  **Time Expansion/Compression** – Operation applied to an audio signal which shortens or lengthens it without changing its pitch content (frequency). Normally this process leaves certain timbral artifacts (altered spectral content).  **Track** – A separate, isolated, concurrent space for any recorded component of a multi-track audio/MIDI recording environment. Separate tracks may be used for separate instruments (i.e. piano, bass, guitar, etc.), but multiple tracks may also be used for the same instrument (i.e. one track for recording the piano’s right-hand, one track for recording the piano’s left-hand, and one track for recording the piano’s sustain pedal). “Track” is also used to refer to separate songs on a CD.  **WAV –** WAV stands for Waveform Audio File Format and is the format for storing (usually) uncompressed, digital audio on Windows/PC computers but is very similar to AIFF audio files. **Waveform** – A graphic representation (picture) of a musical sound, a graph of amplitude (strength) over time. **Waveform Editor** – Digital audio software that allows the user to graphically view and manipulate an audio signal. **XLR Cable** – The most common connectors for connecting microphones to other sound equipment. XLR cables are balanced (reduces interference often introduced with longer lengths) and have a three pin male plug on one end and a female plug on the other.