NVH

NVH stands for Noise, Vibration, and Harshness, a discipline within mechanical engineering that studies and mitigates the generation, transmission, and perception of noise and vibration in products and structures. It addresses both objective measurements and subjective judgments of quality, focusing on exterior and interior noise, vibrations transmitted through a structure, and the overall ride or tactile feel. Harshness refers to the perceived severity of vibration and noise, which is influenced by frequency content and human perception.

Noise is the acoustic energy present in the environment. Vibration is the oscillatory motion of components and structures. Harshness is the perceived quality of those vibrations and sounds, often described in terms of smoothness and comfort. Common sources include engines and exhaust, driveline and tires, wind and aerodynamics, HVAC systems, and electrical equipment.

Measurement and analysis rely on microphones and sound level meters to quantify sound pressure levels (often using dB A weighting) and on accelerometers or velocity sensors to quantify vibration. Analytical methods include time and frequency domain analyses, modal analysis, and transfer path analysis to identify paths from source to receiver. Computational tools such as finite element and vibro-acoustic simulations complement physical testing.

Applications are widespread, with automotive work comprising a large portion of NVH activity, but the field also serves aerospace, maritime, heavy machinery, and consumer electronics. Goals center on reducing noise and vibration, improving ride comfort and perceived quality, and ensuring safety and reliability. Techniques include isolation and mounting improvements, damping, structural stiffening, aerodynamic refinements, sealing and insulation, and, in some cases, active noise control. Standards and testing practices follow industry guidelines from ISO and SAE, among others.