Jays t-JAYS, User Manual

Page: 7 / 116

7
English
Understanding the product specification
Sound Pressure, Decibel and Hz
Sound is an invisible vibration composed of frequencies which
travel in undulations known as sound waves. The amplitude
of vibration produced by an object such as a speaker driver
is proportional to the change of pressure generated as the
wave moves through the medium which surrounds it (such as
air). Therefore, the amplitude of a sound wave is commonly
measured by its pressure level.
The decibel is a non-dimensional, logarithmic scale to denote
a relative change in the strength of a signal or wave. When
placed in the context of sound pressure level; it measures the
nominal threshold of human hearing, relative to the quietest
sound audible to the human ear.
The frequency of instances where a sound wave reaches its
peak during a period of time is measured in Hz (hertz). This is
the number of complete cycles per second. Human hearing is
limited to frequencies between about 20 Hz and 20,000 Hz.
Sensitivity and impedance
Earphone sensitivity is measured in Sound Pressure Level
(SPL). This is essentially a measurement of how loud or easily-
driven a pair of earphones is.
The sensitivity is also influenced by the drivers’ coil impedance
which varies over the frequency range. The higher the SPL
and the lower the impedance the more easily driven your
earphones will be.