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NVH Terms / NVH (Noise, Vibration and Harshness) Terminology

NVH Terms is a term for the interpretation of vehicle noise, vibration and harshness contributing to varying degrees of discomfort what the people can hear and feel as they drive along, including wind noise, road noise, suspension bumps, engine vibrations..

NVH is the research and alteration of the noise and vibration characteristics of cars and trucks in particular. While it's simple to quantify noise and vibration, but harshness is a subjective attribute and is assessed by "bench" tests, or through analytical instruments that can yield results that match human sensations.

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Pitch

The physical quality of sound that relates to the frequency of the wave.

Pitch – Belt Squeaking creates high frequency – Pitched noise roller bearing makes low frequency

 

Camber

The wheel to the road at the vertical angle. The negative camber implies an inner tilt on top of the wheel and is often used to maximise the cornering power of tire at speed with independent suspension.

Radial Force Variation (RFV)

A measurement of the tire's uniformity, under load, in regards to the variation of the load acting towards the center of the tire; commonly referred to as the tire's sidewall variation.

NVH terms – Lateral run out – Number of disturbances – Vibration order

 

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Radial Run out – NVH Terms

A condition where a rotating component does not rotate in a true plane. The component moves up and down on its rotational axis.

Resonance

The tendency of a system to respond increasingly to a compelling force oscillating at, or near, the natural frequency of the system. This causes a sudden and large vibration.

Vibration – Compelling force – Beat bead seating – Reliability analysis – Durability analysis

 

Road Noise

A noise that occurs while driving on gravel or roughly paved roads at all vehicle speeds, or when a vehicle is coasting.

Harshness – NVH Harshness – Lack of suspension feel

 

Shake, Lateral

A side-to-side vibration of the body, seats, and steering wheel.

Shake, Vertical

An up and down vibration of the body, seats, and steering wheel.

Vehicle Shake – Steering wheel shake – Vibration in steering wheel – Vertical shake – Lateral shake

 

Shimmy, High-Speed – NVH Terms

A vibration that causes the steering wheel to oscillate when driving on smooth roads at high speeds.

Shimmy, Low-Speed

A vibration that causes the steering wheel to oscillate when driving across a bump at low speeds.

Shimmy steering wheel to oscillate – High speed shimmy – Low speed shimmy due to roughness of road

 

Source Component

The component that is diagnosed as being the root cause of a vibration or noise concern.

Sound – NVH Terms

The result of a vibrating disturbance of an object, which produces waves that transmit out from the source.

Noise – NVH Noise – Types of noise – Unexpected sound

 

Static Balance

The method of balancing a tire and wheel assembly in a single plane. Static balancing removes only the lateral (side to side, wobble) imbalance and the tire and wheel assembly could possibly have a radial (up and down) vibration.

Torque Sensitive Vibration or Noise

A vibration or noise that is sensitive to different loads and torque, applied to the drive train of a vehicle. The vibration or noise changes when the throttle position or transmission gearing is used, during a road test, to change the torque applied to the drive train.

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Vibration – NVH Terms

The repetitive motion of an object, back and forth or up and down, which may be felt or heard.

Automotive NVH – Brake Squeal – Vehicle NVH – Brake Squeal analysis – Finite element analysis – Vibration analysis

 

Wheel Diameter

The dimension of a wheel measured on the inside of the wheel at the bead seat area.