Acoustic Glossary

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

---

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

Home • Glossary Search • Certified Instrumentation for Hire