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380_076
Function
A soundpipe is connected between the air mass meter and the throttle valve unit in the air intake tract.
The soundpipe made up of three parts: the primary pipe, which is connected to the air intake tract, the sound
generator and the secondary pipe, which is connected to the vehicle interior via the engine bulkhead. The
primary and secondary pipes as well as the sound generator are configured in such a way that it is possible to
influence the "bandpass characteristic"*, and hence the acoustic transmission range. However, the sound
generator is the key component.The system is designed such that the sound becomes meatier when the
driver demands more power from the engine.
The pressure pulsations which during the gas exchange cycle are transmitted to the membranes in the sound
generator, where they are amplified by the sound generator and relayed to the vehicle interior. Another further
task the membranes is to seal the gas flow between the air intake tract and the vehicle interior. The foam core
in the sound generator has the task of maintaining the shape and position of the membranes.
* A bandpass characteristic is produced, for example, by connecting the highpass and lowpass filters in
series. Only a defined range of frequencies is allowed to pass, depending on the circuit configuration.
Securing clip
Secondary pipe
Primary pipe
O-ring
Foam core
Membranes
from intake
manifold
Sound generator
to vehicle
interior