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Basic operation
How to operate the Sound Adjustment Mode
About Sound Adjustment Mode
The system has several features that allow you to adjust the acoustic
characteristics inside the cabin. In the Sound Adjustment Mode, the
following characteristics can be adjusted.
Crossover
The frequency band that is stored by audio media such as CDs is a
fairly wide range from 20 Hz to 20 kHz, and it is difficult for a single
speaker to be able to play back all frequencies in such a wide range.
Because of this, several speakers can be used, with different
frequency bands (such as treble, medium and bass) allotted to each
speaker so that wide frequency ranges can be played back.
The "Crossover" function is used to allot the frequency ranges that
are to be played back by each speaker in accordance with the
installed speaker units and the layout of the speakers, in order to
obtain the maximum level of performance from the speakers and to
provide the most stable frequency characteristics.
The crossover function includes a high-pass filter (HPF) for playing
back treble sounds, and a low-pass filter (LPF) for playing back
bass sounds. In addition, the HPF and LPF are used in combination
in order to play back sounds in the medium range.
For example, when adjusting the HPF, frequencies that are lower
than the specified frequency are progressively dampened, rather
than simply not being played back at all. The "slope" adjustment
function is the function that is used to adjust these dampening
characteristics.
The slope characteristics of a filter are such that with larger slope
values (for example 12 dB/oct), the slope becomes steeper, and so
the amount of sound mixing in with neighboring bands becomes
less so that only the target band is played back. However, it also
causes the merging of sound between speakers to become poorer
and can result in greater distortion.
-3dB
20Hz
Bass range Medium range Treble range
20kHz
fc1(LPF) fc2(HPF)
fc*: Cutoff frequency
fc3(LPF) fc4(HPF)
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