Electric Vehicles & Acoustics

Meeting the acoustic challenges of electric vehicles

Global builds of electric vehicles (EVs) are forecasted to reach 10 million by 2025, accounting for more than 10% of total vehicle builds. The design of EVs requires a different approach to handling acoustic issues, and with proven sound damping performance, Saflex® Acoustic interlayers are the ideal solution for mitigating unwanted and unpleasant noise.

EV acoustics differ from those of internal combustion engines (ICEs) in three main areas: noise sources, material weight, and vehicle design. Once the sound source is determined, the use of acoustic interlayers can offer a reliable solution.

Noise sources

The three main sources of interior noise are the vehicle’s engine/motor, tires and road surface, and wind turbulence. Because electric motors tend to contribute a much lower overall sound intensity than combustion engines, tire/road noise and wind turbulence become much more relevant sources in EVs. At low speeds, tire noise tends to dominate the EV cabin. With acceleration, wind noise takes over and becomes the dominant noise source much earlier in the acceleration curve than it does in combustion engine vehicles. At the same time, pressure levels shift toward the higher frequency ranges often associated with consumer complaints and driver distraction, making improved acoustic damping a necessity. Saflex Acoustic interlayers perform especially well in damping higher-frequency wind noise, reducing transmission levels by up to 4.5 dB in the 1,000–5,000 Hz range versus standard laminated glass. The new Saflex E series enhanced acoustic interlayer offers up to an additional 2 dB noise reduction in the 5,000–10,000 Hz range commonly associated with the most unpleasant and distracting sounds. This may help lower the stress of driving, reduce fatigue, and enable easier conversations between drivers and passengers.

Click here to download a 2011 study from SAE International and Society of Automotive Engineers of Japan, Inc. about interior noise comparisons between EVs and ICEs.

Material weight and range

Fuel consumption is an important factor in the economics and environmental impact of an ICE, but the time required to refill the fuel tank is relatively insignificant in terms of the overall consumer experience and utility of the vehicle. With EVs however, range is a key differentiating factor due to longer recharging times. Since energy consumption is negatively impacted by weight, EV manufacturers place a strong emphasis on the reduction of excess weight through material selection, including the use of thinner glass. The downside of these choices is generally less effective noise damping as a function of mass. Saflex Acoustic interlayers can help reduce sound without adding weight.

Vehicle design

Many EVs are designed with heavy, dense batteries below the floor to lower the center of gravity as much as possible. To create this required space, the rear seats often need to be positioned higher than in ICEs. EV designers then create the perception of more headspace and openness for rear-seated occupants with large, panoramic sunroofs, usually without closeable shades. The result? Sunroof glass becomes more relevant in blocking wind noise from entering the cabin. Fortunately, this can be balanced with laminated glass using Saflex Acoustic interlayers. PVB interlayers can help reduce the overall sound transmission through the sunroof.

Learn more about how Saflex Acoustic interlayers can help you lessen the risk of audible distractions.