I’ll never forget the experience, as a kid, of lifting the massive steel hood of my father’s 1971 Dodge Monaco and seeing nothing but V8 engine and a few rubber hoses. The vast compartment was so uncluttered, I could look straight down and see the pavement. By comparison the view under today’s vehicle hoods reveals a dense landscape of technologies aimed at acoustic control: covers, shields and insulators designed to keep injector clatter, induction honk and even pulley whirl muffled.
Supplier innovations are central to winning the ongoing war with NVH—noise, vibration and harshness. The battle started decades ago and will certainly increase in the future. This is an engineering realm with numerous trade-offs involving total piece cost, capital cost, stranded fixed capital, tooling complexity/count, system optimization, flexibility, intellectual property and even downstream warranty. But because NVH (more accurately, the lack of it) has direct impact on the end customer, it has become a commitment rather than an option across vehicle segments.
Controlling NVH and its annoying little cousin, BSR (buzz, squeak and rattle) is a never-ending crusade. What value is a new fuel-efficiency technology such as direct injection, for example, when it increases under-hood noise? Customer satisfaction, sales and future vehicle value will suffer. The goal is to offer ‘no compromise’ technology, with suppliers responsible for raising the bar with each new model.
The “N” in NVH is a constant challenge for engineers but offers opportunities for suppliers. The advent of acoustic glass came from collaborations among glass and film/laminate companies. Advanced door sealing systems, fuel tank isolation, floor/door panel insulators, foam-based HVAC ducting, laminated structural materials in the cowl/floor and a focus on new fastening technologies are critical to today’s acoustic experience and mainly come from the supply base.
This journey is more than material/process science—it also includes system optimization. Nine and ten-speed transmissions are only as smooth and unobtrusive as their calibrations allow them to be. New material/process innovations by chemical-solution providers such as Dow and BASF, and component/system suppliers including Rochling, MSC, Mahle and Autoneum are key to ensuring systems “tuned” to the customer’s ear and all control surfaces including the steering wheel and pedals.
Suppliers be forewarned: the OEMs’ drive to reduce and abate NVH is just getting started. The IHS Markit forecast for vehicle electrification and greater regulation-driven emissions performance underscores this. Per the latest forecast, 32% of the global light vehicle sales in 2025 will exhibit some sort of advanced electrification—mild-, plug-in and full-hybrid or a battery-electric vehicle. As the rate of vehicles operating under electrified propulsion rises, noise from other systems becomes more audible and will require control. HVAC, wind, tire (low rolling resistance), external noise and electric motor/gear resonance will become more apparent in the absence of the combustion engine.
There’s also vehicle lightweighting, a trend that can exasperate NVH engineers. The goal for many consumers is to have an even quieter interior than in the past. Thus shifting to materials outside the norm (higher gauge steels, aluminum sheet/structure or alternative plastic formulations/applications) can lead to the need for insulation countermeasures. Suppliers need to understand this gap and respond. In this case, less is more when optimizing mass reduction while maintaining the acoustic experience and vehicle performance. This will open new doors for supplier innovations throughout the tiers.
New opportunities have emerged recently in noise abatement/compensation and attenuation. The major vehicle audio companies including Panasonic, Bose and Harman are developing solutions to mask unwanted frequencies and enhance the driving experience. As alternative materials and technologies are integrated into tomorrow’s offerings an emerging market is born.
Virtually every supplier will need to consider NVH innovations, as the “sound of silence” becomes a baseline for future business.