![]() ![]() Therefore, the development of brake systems with minimum noise issues are highly prioritized in the automotive industry. The brake noise can lead to poor results in surveys of customer satisfaction and high warranty costs. This will in turn cause a lot of irritation and disturbance to the car owner and any person near the vehicle when it occurs. The noise is caused by friction-induced vibrations, which make the brake system radiate noise. The HVAC system is one of the dominating noise sources in the vehicle during cool down or heat up and needs a lot of careful design work.īrake noise is a chassis-related noise and an area of great concern for OEMs across the world. System-actuated sounds are controlled independently of any action from the driver or passengers and the reason why the sound is not always easy to understand. Customer-actuated sounds are directly related to an action like opening or closing a door or power-operating windows and will likewise provide user feedback. Finally, acoustic absorption material at critical locations is used to improve the acoustic interior comfort.Ĭomponent noise is often divided into two areas: customer-actuated sounds and system-actuated sounds. Structural damping and heavy-layer isolation mats must be optimized for best performance and lowest weight and cost. This reduces high-frequency leakage and increases the overall NVH performance. The first step is to make sure that the body is sealed as much as possible. ![]() The sound package is closely related to most of the NVH areas. Extra focus is on tire cavity resonance noise around 200-250 Hz and tread noise. The requirements include noise level and frequency balance. ![]() Requirements are normally based on subjective evaluation, benchmarking and experience. Road excitation contributes to the interior noise both structure-borne and airborne. Road noise is one of the most annoying interior noises in a vehicle. It concerns the overall noise level inside the vehicle at its full speed range and is a way of testing the general experience of a vehicle’s acoustic comfort.Īrticulation Index (AI) is often used as a good index for sound insulation and sealing as well as speech intelligibility. Total interior noise is a good measurement for benchmarking and a measurement often used by automotive magazines for comparison of different car models. See our complete application offering within electric vehicles here. Another option is to use GRAS 147AX CCP Rugged Pressure Microphone, which has a unique mounting system, MagMount TM, ensuring precise repeatable tests in the cabin in combination with driver seat measurements using GRAS 146AE ½” CCP Free-field Microphone Set. GRAS 47HC ½” CCP Low-noise Microphone System. We recommend to use a low-noise type microphone like e.g. It therefore needs to be adjusted to the new environment. Passive noise cancellation: Traditional ways of vehicle noise cancellation such as acoustic package and anti-vibration mounts will still be used for EVs/HEVs. This in combination with wind/road/tire noise, which are all dominant noises, makes it more relevant to use pressure microphones instead of directional free-field microphones in the cabin.Īctive noise cancellation: The phase is very hard to control inside the cabin – and if not controlled, it can instead amplify the noise. Many EVs/HEVs use a more distributed powertrain with individual electric engines. Many sound sources have very limited energy at 20 kHz which makes transfer path analysis from the engine bay more difficult. A main reason for this is that the general increase in high-frequency content will make it more difficult to do TPA/ENR types of measurements. Measuring inside the cabin is more challenging on an EV compared to an ICE. Learn more about the challenges and how to select the right microphone Read about electric applications here.Ī chassis-related noise and a big problem for car manufacturers. ![]() These are mostly electrical or driven by the engine belt, and sometimes hydraulic. Testing related to how road excitation contributes to the interior noise both structure-borne and airborne – depending on well-defined road surfaces and tires.Īn area that affects most of the NVH areas.Ĭoncerns all additional systems like the heating, ventilation and air conditioning (HVAC) system, power windows, etc. Vehicle interior noise, vibration and harshness (NVH) involves a number of different tests – all related to noise inside the vehicle originating from road, body, chassis and components of the vehicle.Ī way of testing the general experience of a vehicle’s acoustic comfort. ![]()
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