Protecting front-seat passengers against engine noise
Although excess engine noise is not desirable, it is important to use acoustic insulation for the engine bay such that the driver can still recognise when the engine is revving too high, or if there are any unusual and unhealthy noises coming from the engine.
But the front-seat passenger needs no such feedback, allowing their position to be more acoustically insulated against engine noise if desired – and newly published research shows why this is an especially good idea for low-frequency noises.
Writing in the International Journal of Innovative Research in Technology & Science, vehicle noise and environmental acoustics researcher David Ibarra explains that at lower frequencies, engine noise tends to leave the compartment via the route with the fewest obstacles.
In the test vehicle, which was left-hand drive, this meant more low-frequency noise entered the right-hand side – the passenger side – of the interior cabin, where it did not encounter the physical barrier of the steering column and other driver-side controls.
“At low frequencies [there is] a trend to radiate to the side of the vehicle that has less internal components behind the engine,” he writes.
By applying acoustic insulation for the engine bay and interior cabin particularly to tackle low frequencies on the passenger side, this unwelcome noise can be prevented from entering, leaving the beneficial feedback more audible for the driver.