Acoustics/Interior Sound Transmission
Introduction to NVH
Noise is characterized by frequency (20-20kHz), level (dB) and quality. Noise may be undesirable in some cases, i.e. road NVH yet may be desirable in other cases, i.e. powerful sounding engine.
Vibration is defined as the motion sensed by the body, mainly in 0.5Hz - 50Hz range. It is characterized by frequency, level and direction.
Harshness is defined as rough, grating or discordant sensation.
Sound quality is defined according to Oxford English Dictionary, "That distinctive Quality of a Sound other than it's Pitch or Loudness"
In generally, ground vehicle NVH and sound quality design are attributed by the following categories:
1.) Powertrain NVH and SQ: Interior Idle NVH, Acceleration NVH, Deceleration NVH, Cruising NVH, Sound Quality Character, Diesel Combusition Noise, Engine Start-Up/Shut-Down
2.) Wind Noise: Motorway Speed Wind Noise (80-130kph), High Speed Wind Noise (>130kph), Open Glazing Wind Noise
3.) Road NVH: Road Noise, Road Vibration, Impact Noise
4.) Operational Sound Quality: Closure Open/Shut Sound Quality, Customer Operated Feature Sound Quality, Audible Warning Sounds
5.) Squeaks and Rattles
== Noise generation ==
Structural vibration response
Structural acoustic response
Applications to vehicle interior sound transmission