Acoustic Glossary


 

U : Sound and Vibration Terms, Definitions, Units, Measurements ...

UKAS : United Kingdom Accreditation Service is the national accreditation body recognized by government to assess, against internationally agreed standards, ...

UK Government Environmental Noise Regulations


Aircraft Noise indicators • LAeq,16h • Lday • Levening.
Industrial Noise and Port Noise indicators • LAeq,16h • Lday • Levening.
Railway Noise indicators • LAeq,6h • LAeq,16h • LAeq,18h • Lday • Levening.
Road Traffic Noise indicators • LA10,18h • LAeq,16h • Lday • Levening.

Ultrasound Definition IEC 801-21-04,

acoustic oscillation whose frequency is above the high-frequency limit of audible sound (about 16 kHz)
Uncoupled Mode Definition IEC 801-24-18, normal mode oscillating independently of other modes.

See also • coupled modes

Undamped Natural Frequency the natural frequency of a structure.

Undamped Natural Frequency Definition IEC 801-24-09, frequency of free oscillation resulting from only elastic and inertial forces of the system.

See also • natural frequency
Under-range, the input to the sound level meter is too low for the current measurement range.

Under-range %, percentage of time that an under range occurred.

Units •

SI Units
sound absorption is the sabin
sound energy is the joule (J)
sound energy density is the J/m3 (joule per metre-cubed)
sound energy flux = W (watt)
sound intensity is the W/m2 (watt per metre-squared)
sound power is the W (watt)
sound pressure is the pascal
 
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