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,16hLdayLevening.
Industrial Noise and Port Noise indicators • LAeq,16hLdayLevening.
Railway Noise indicators • LAeq,6hLAeq,16hLAeq,18hLdayLevening.
Road Traffic Noise indicators • LA10,18hLAeq,16hLdayLevening.

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
Units • sound absorption is the sabin
Units • sound energy is the joule
Units • sound energy density is the J/m3 or W·s/m3
Units • sound energy flux = W/m2 = J·s/m2
Units • sound pressure is the pascal
 
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