Sound Quality Measurement
In layman’s terms, psychoacoustics is the bridging of the physical representation of sound and its subjective human hearing perception. Sound quality on the other hand, which is a discipline that falls within the field of psychoacoustics, defines the distinctive character of a sound other than its pitch or loudness (Dunne, 2003).
Sound quality metrics, if appropriately selected, can be used as a measure to objectively establish the comfort and refinement of a vehicle’s sound signature. Newly developed tonal metrics are especially relevant to electric vehicles where noise levels may not be excessive but may be particularly intrusive.
In the automotive industry, such as the EV bus sector, sound quality measurement and assessment is neither trivial nor paralleled. Unlike those of conventional ICE vehicles, EV powertrains do not radiate broadband masking noise from their engines.
Noise measurements from EVs are usually conducted under several experimental test conditions. Acoustic performance is evaluated through binaural playback of recordings in listening rooms or artificial simulators, vehicle demonstrators, as well as subjective assessments when driving on test tracks.
Electric Vehicles Sound Quality | New Challenges
New Noise Problems Exposed
–Tonal Noise
-Sound level VS Sound Quality
-Space, weight, thermal
Reduced noise would appear to be a “win” for vehicle acousticians in electric bus original equipment manufacturers (OEMs). Unfortunately, the new challenge emanating from lack of broadband masking and characteristic of electric vehicle architecture is the variety of new tonal noises.
A new challenge for acoustic engineers is that components of EV powertrain noise sources emit mid to high-frequency tonal noises, also referred to as whining noise. Passengers have become somewhat accustomed to the conventional broadband noise of ICE powertrains, whereas the whining noise of the EV powertrain is an unexpected intrusion for a vehicle widely marketed as “quiet” or “silent”.
Noise measurements from EVs are usually conducted under several experimental test conditions. Acoustic performance is evaluated through binaural playback of recordings in listening rooms or artificial simulators, vehicle demonstrators, as well as subjective assessments when driving on test tracks.
Electric Vehicles and Tonality
At steady, low-speed driving conditions, where road and wind noise levels are low, sound files from electric vehicles usually contain prominent tonal noises, as demonstrated in white paper issue four.
In white paper issue 5, we expatiated on the science of sound quality as it pertains to human perception and tonality, together with the technique involved in understanding how humans quantify sounds, as supposed to the calculations and algorithms employed by computer applications. We also delved a little deeper into assessing the tonal components contained in the sound file of an electric vehicle in the wide-open-throttle (WOT) driving condition, as opposed to a steady, low-speed driving condition as in the previous white paper.
Electric Motor Wraps
Electric motor wraps are one of the solutions that may be used in treating tonal noises from electric bus and coaches. Reductions of over 15 dB have been achieved on narrow band peaks following treatment of EV noise sources using Ventac’s motor wrap. It is important to note that the effectiveness of any high frequency noise treatment is limited by gapping (such as around pipes, services, and rotating elements). However, encapsulating the noise at source maximises the noise reduction achieved and minimises the material and weight required.
Ventac are international providers of Noise Analysis & Testing Programs, Component Design, Material Composites, Engineering & Manufacturing Services for Vehicle Noise Control for over 15 years. We are an established name in the supply of innovative and high-performance noise control solutions to OEMs of Bus & Coach, Specialist, Construction and Agricultural Vehicles.
For further information, or to talk to the acoustics team about your electric vehicle noise control project, call us on +353 (0)45 851500 or email us at info@ventac.com.
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