Glossary of Audio Terms 23
Inductance .
The property of an electrical circuit by which
a varying current in it produces a varying magnetic field
that introduces voltages in the same circuit or in a nearby
circuit. It is measured in henrys.
Inductor .
A device designed primarily to introduce induc-
tance into an electrical circuit. Sometimes called a choke
or coil.
Linearity .
The extent to which any signal handling pro-
cess is accomplished without amplitude distortion.
Midrange .
The middle frequencies where the ear is the
most sensitive.
Passive crossover .
Uses no active components (transis-
tors, IC’s, tubes) and needs no power supply (AC, DC,
battery) to operate. The crossover in a typical loudspeak-
er is of the passive variety. Passive crossovers consist of
capacitors, inductors and resistors.
Phase .
The amount by which one sine wave leads or lags
a second wave of the same frequency. The difference is
described by the term phase angle. Sine waves in phase
reinforce each other; those out of phase cancel.
Pink noise .
A random noise used in measurements, as it
has the same amount of energy in each octave.
Polarity .
The condition of being positive or negative with
respect to some reference point or object.
RMS .
Abbreviation for root mean square. The effective value
of a given waveform is its RMS value. Acoustic power is
proportional to the square of the RMS sound pressure.
Resistance .
That property of a conductor by which it oppos-
es the flow of electric current, resulting in the generation of
heat in the conducting material, usually expressed in ohms.
Resistor .
A device used in a circuit to provide resistance.
Resonance .
The effect produced when the natural vibra-
tion frequency of a body is greatly amplified by reinforcing
vibrations at the same or nearly the same frequency from
another body.
Sensitivity .
The volume of sound delivered for a given
electrical input.
Stator .
The fixed part forming the reference for the moving
diaphragm in a planar speaker.
THD .
The abbreviation for total harmonic distortion. (See
Distortion)
TIM .
The abbreviation for transient intermodulation distortion.
Transducer .
Any of various devices that transmit energy
from one system to another, sometimes one that converts
the energy in form. Loudspeaker transducers convert electri-
cal energy into mechanical motion.
Transient .
Applies to that which lasts or stays but a short
time. A change from one steady-state condition to another.
Tweeter .
A small drive unit designed to reproduce only
high frequencies.
Wavelength .
The distance measured in the direction of
progression of a wave, from any given point character-
ized by the same phase.
White noise .
A random noise used in measurements, as
it has the same amount of energy at each frequency.
Woofer .
A drive unit operating in the bass frequencies
only. Drive units in two-way systems are not true woofers
but are more accurately described as being mid/bass
drivers.
