Audio Terminology And Definitions Dictionary
R Symbol for resistance or resistor.
Reactance A frequency selective resistance. Inductance and capacitance are the two forms of reactance. The combination of resistance and
reactance is impedance.
Pattern The area over which a loudspeaker radiates most
of its energy and the evenness with which this energy is distributed within that
area. Speakers may be omnidirectional and radiate freely in all directions or
directional with specifically designed radiation patterns. Directional speakers
can be broken down further into three main groups: direct radiators (energy
distributed primarily to the front of the speaker), bipolar (equal energy
radiation to the front and rear of the enclosure with matching polarity), and
dipolar (equal energy radiation to the front and rear of the enclosure but
An artifact of single-chip DLP display devices that results from the interaction
between the light source, the color wheel needed in a single-chip device, and
the chip itself. The "rainbow effect" presents itself as brief color
flashes when the viewer looks rapidly from side to side on the screen or from
the screen to a point in a room. Fortunately, not everyone is sensitive to
An image file of minimally processed data received from a digital camera. Most
camera manufacturers have their own proprietary version of the RAW image format
and their own file suffixes. Canon, for example, uses .crw or .cr2 for their
version of RAW. Nikon's RAW files end in .nef, while Sony uses .arw and .srf
suffixes. Professionals prefer shooting in RAW because the additional
information these large files contain allows greater flexibility in
post-production editing. Because the image is basically unprocessed (as compared
to a JPEG image), RAW files can retain very subtle color variations and fine
detail. Color changes, contrast adjustments, and other manipulations of a RAW
image yield significantly fewer digital artifacts than the same changes made to
a comparable JPEG file.
One of the most popular formats for streaming content on the Internet, RealMedia
includes the RealAudio codec for sound clips and RealVideo codec for movies.
RealAudio and RealVideo files are often given the common RealMedia.rm file
extension. RealMedia is a container format that's often heavily compressed for
streaming over dial-up Internet connections. RealMedia variable bitrate (RMVB)
has been developed for VBR streaming files.
audio or audio/video component that combines a tuner, preamplifier, and power
amplifier in a single chassis.
Rectification An essential process in the conversion of AC to DC by means of a half wave rectifier, a form
of diode which is a key element in a power supply.
Resistance Pure resistance is measured in Ohms. Resistance in the form of resistors blocks the flow of
electric current in a linear or non frequency selective manner.
The characteristic of a physical object that causes it to vibrate when excited
by an external force and, once excited, to keep vibrating after the original
stimulus ceases. Examples of resonance include a tuning fork and a bell. An
unwanted resonance, particularly in a loudspeaker enclosure, can color the
output of the entire loudspeaker system by introducing frequencies that are
unrelated to the original signal. Rooms and loudspeakers are resonant systems.
Reverberation Time The time it takes for a sound generated in a room to drop to 60dB below its original level. It is a measure of the size and reflectivity of the room boundary surfaces. A typical listening room
measuring about 2.5 x 6.5 x 3.75 meters (HxLxW) will have a Reverberation Time of about 0.4 seconds. Major concert halls have a far longer RT in the region of 1.5 to 2.5 seconds.
RF Radio Frequency. Typically frequencies upwards of 70kHz through to MHz.
RFI Radio Frequency Interference. The disruption
of radio signal reception caused by any source which generates radio waves at the same frequency and
along the same path as the desired wave.
RIAA Record Industry Association of America. It is the RIAA disc equalization curves that are almost
universally followed by record companies making LPs, and by hardware manufacturers configuring their
Roll Off A
gradual attenuation (either intentional or unintentional) of a signal, usually
above or below a given frequency known as the "corner frequency."
rms Root Mean Square. rms qualifies an amplifier power output specification to signify continuous power
output as opposed to peak or transient power.
Rumble Turntable rumble is a very low frequency noise
caused usually by main bearing noise. It is usually a sign of poor bearing lubrication.