NVH Terminology / NVH Glossary
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.
Continuation is available in the following post:
Audible Range of Sound – NVH Terminology
Sounds that are in the range of 20 to 20,000 Hertz (Hz).
VH Terminology – Audible range of sound – Pitch intensity sound – Soundwaves – NVH noise level
Amplitude
The vertical measurement between the top and bottom of a wave. Also see magnitude.
Amplitude Sound Cycle – NVH Terminology
Vibration amplitude – Sound waves – Vibration level
Beat
An NVH concern produced by two sounds that is most noticeable when the frequency difference is 1 to 6 Hz.
Bead Seating
The process of seating the tire to the rim. If properly lubricated the bead seating occurs when the tire and wheel are assembled.
Compelling Force
A vibrating object acting upon another object that causes the other object to vibrate.
Cycle
The path a wave travels before the wave begins to repeat the path again.
Dampen
To reduce the magnitude of a noise or vibration.
Dampers
A component used to dampen a noise or vibration. Foam and rubber are commonly used to dampen vibrations.
Dynamic Balance
A procedure that balances a tire and wheel assembly in two planes. Dynamic balance removes radial and lateral vibrations.
Droning, High-Speed
A long duration, non-directional humming noise that is uncomfortable to the ears and has a range of 50 mph (80.5 kph) and up.
Droning, Low-Speed
A long duration, low-pitched noise that is non-directional and has a range of up to 30 mph (48 kph).
Droning, Middle-Speed
A long duration, low-pitched noise that is non-directional and has a range of 30 to 50 mph (48 to 80.5 kph).
Electronic Vibration Analyzer
An electronic NVH diagnostic tool that measures frequency and amplitude.
Frequency
The number of complete cycles that occurs in a given period of time.
Harshness
An aggressive suspension feel or lack of give in response to a single input.
Hertz
The unit of frequency measurement in seconds (a vibration occurring 8 times per second would be an 8 Hz vibration).
Hiss
Steady, high-frequency noise. Vacuum leak sound.
Hoot
A steady, low-frequency tone, sounds like blowing over a long neck bottle.
Howl
A mid-range frequency noise between drumming and whine. Also described as a hum.
Intensity
The physical quality of sound that relates to the amount and direction of the flow of acoustic energy at a given speed.
Lateral Run out
A condition where a rotating component does not rotate in a true plane. The component moves side-to-side (wobbles) on its rotational axis.
Magnitude (Amplitude) – NVH Terminology
The amount of force or the intensity of the vibration. The magnitude or strength of a vibration is always greatest at the point of resonance.
Medium
Provides a path for sound waves to travel through.
Natural Frequency
The frequency that a component will vibrate the easiest. Normally, the larger the mass, the lower its natural frequency.
- Engine block (2-4 Hz)
- Tire and wheel assemblies (1-15 Hz) – proportional to vehicle speed
- Suspension (10-15 Hz
- Driveline (20-60 Hz)
- Differential components (120-300 Hz)
Noise
The unpleasant or unexpected sound created by a vibrating object.
Order
The number of disturbances created in one revolution of a component.
Phase
The position of a vibration cycle relative to another vibration cycle in the same hertz rate (time frame).
