7
English
Understanding the product specication
Sound pressure, Decibel and Hz
Sound is an invisible vibration composed of frequencies
which travel in undulations known as sound waves. The am-
plitude 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 it
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 inuenced by the drivers’ coil imped-
ance which varies over the frequency range. The higher the
SPL and the lower the impedance the more easily driven your
earphones will be.