Acoustic Glossary

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 of Sound, the most common units are
sound absorption is the sabin
sound energy is the joule
sound intensity is the watt per metre-squared
sound power is the watt
sound pressure is the pascal