RAM
Short for "Random Access Memory". This is the memory that handles your working data; its capacity is expressed in MB (megabytes). Normally this memory is "volatile", which means that the contents are only saved for as long as the device is powered up.

RealAudio
A popular streaming format for audio and video developed by RealNetworks. The format's use is trageted toward low bitrate streaming.

real time
Occurring at the same time as other, usually human, activities. In real-time sequence recording, timing information is encoded along with the note data by analyzing the timing of the input. In real-time editing, changes in parameter settings can be heard immediately, without the need to play a new note or wait for computational processes to be completed.

reconstruction filter
A low-pass filter on the output of a digital-to-analog converter that smoothes the staircase-like changes in voltage produced by the converter in order to eliminate clock noise from the output.

Regeneration
> resonance; > feedback.

Release
The portion of an envelope that begins after the key is lifted ; the final period of an envelope during which a sound's attribute (such as volume) decreases from the sustain level to 0 (silence).
This period of the envelope defines how a sound finishes off. A long release time causes a sound's attribute to fade away slowly, while a short release time causes it to drop out quickly.

release velocity
The speed with which a key is raised, and the type of MIDI data used to encode that speed. Release velocity sensing is rare but found on some instruments. It is usually used to control the rate of the release segments of the envelope(s).

Resample
To recalculate samples in a sound file at a different samplerate  than the file was originally recorded.

Resolution
The fineness of the divisions into which a sensing or encoding system is divided. The higher the resolution, the more accurate the digital representation of the original signal will be.

Resonance
A function of a filter in which a narrow band of frequencies (the resonant peak) becomes relatively more prominent. If the resonant peak is high enough, the filter will begin to oscillate, producing an audio output even in the absence of input. Filter resonance is also known as emphasis, and as Q. It is also referred to in some older instruments as regeneration or feedback, because feedback was used in the circuit to produce a resonant peak.

Reverb
An effect that simulates natural reverberations (sound reflections) that occur in different rooms and environments to create an ambience or sense of spaciousness.

ring modulator
A special type of mixer that accepts two signals as audio inputs and produces their sum and difference tones at its output, but does not pass on the frequencies found in the original signals themselves. See clangorous.

RIAA
Recording Industry Association of America. A trade organization that represent music industry financial and legal interests. Among other things, it works to influence legislation, protect the intellctual property rights of artists and record companies, and fight music piracy worldwide.

Rip
1) A slang for digital audio extraction, copying data from one format to another more useful format. The most common example is found in the phrase "CD Ripping" which means to copy audio tracks from an ordinary audio CD and save them to hard disk as a WAV, MP3 or other audio file, which can then be played, edited or written back to another CD.
2) lat.: = reqiescat in pacem = sleep in (heavenly) peace

rolloff slope
The acuity of a filter cutoff frequency. Rolloff is generally measured in decibels (dB) per octave. A shallow slope, such as 6 dB per octave, allows some frequency components beyond the cutoff frequency to be heard, but at a reduced volume. When the rolloff slope is steep (on the order of 24 dB/oct), frequency components very close to the cutoff frequency are reduced in volume so much that they fall below the threshold of audibility. > filter, > pole.

ROM
Read-only memory. A type of data storage whose contents cannot be altered by the user. An instrument's operating system, and in some cases its waveforms and factory presets, are stored in ROM. Compare with RAM.

Routing
Generally refers to how a signal is sent through signal circuits; is often used to describe specific input and output "assignments".

Run-time discrepancy
Minimal delay of audio signals, usually in the millisecond range. Generally not a huge problem unless signals are directly linked (e.g. the two channels in a stereo recording. In this case, these differences generate phase shifting and comb filter effects.