We all want quieter vehicles with less noise, vibration and harshness (NVH). Low-noise interiors offer better comfort for drivers and passengers during long journeys – but how quiet is too quiet?

Noise is one element in NVH where there is a sweet spot, for reasons we’ll look at in detail below. For that reason, vehicle noise reduction can’t just be about eliminating engine noise at source, but must involve preventing that noise from penetrating the interior cabin.

At the same time, interior noise levels should be as low as possible. So as we move towards an all-electric automotive future, what does that mean for vehicle noise reduction as part of efforts to improve NVH?

The answer is a multi-layered approach. This involves quieter technologies like electric vehicles, insulated engine bays and underbody, combined with felts and foams that eliminate any remaining vibrations from vehicle interiors.

With all the elements in place, travelling by road can be an enjoyable and even peaceful experience, while allowing cars to make the noise that is not only valuable, but in some cases essential.

Why vehicle noise is needed

Vehicle noise – and especially engine noise – is an important part of the driving experience. We can all appreciate the rumble of a supercharged engine or the squeal of tyres taking a turn at high speed.

Away from the track, vehicle noise has a part to play in ensuring the safety of pedestrians. Every second of every day, someone somewhere is listening for an approaching car before deciding whether it’s safe to cross a road.

Electric vehicles have the potential to run extremely quietly, with only a faint whirring of gears. Battery power itself is silent-running, and that raises questions for road safety.

In a recent news story on the Volvo Group website, the automotive manufacturer called pedestrian safety “a vital consideration when designing the soundscape of electric vehicles” and added: “Silence can in some aspects be too much of a good thing.”

When interior noise is troublesome

Some engine noise in the interior cabin is useful, as a source of feedback for the driver. Excess tyre noise can be an indication of skidding or incorrect tyre pressure, while a noisy engine can mean the vehicle is in the incorrect gear.

But excess interior noise is unwelcome. A noisy car is less pleasant to drive, especially at speed. As we make more use of voice recognition and spoken-word systems like satnav and virtual smartphone assistants, we need interior cabins to be as quiet as possible.

This is why, in addition to reducing vehicle noise at source, it’s equally important to insulate interiors to eliminate excess engine noise, along with internal sounds like vibration and rattling of interior trim.

How vehicle noise is changing

Better vehicle noise reduction and emerging engine technologies such as all-electric vehicles mean the nature of automotive acoustics is changing.

Over the coming decade, EVs are set to become the standard as we aim for widespread uptake by 2030, and that means finding the new sweet spot for external and internal noise levels alike.

Thanks to a long history of developing acoustic insulation for vehicles with combustion engines and battery power, the materials are already available to support this switch to sustainable technologies.

All that remains is for manufacturers to find that perfect balance that offers valuable feedback to the driver, enough noise to alert pedestrians to the presence of the vehicle, but minimal NVH and external noise pollution too.

To find out more about the innovative NVH solutions Interflex supply, including interior trim, under carpet, boot and door seals, please call us on 01949 861 494 or email sales@interflex2000.com.