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Appendix B

Relative response (dB)

Burst duration, t (milliseconds)

Figure B-4:Impulse response to a tone burst

Room Criterion Curves (RC)

Room Criterion curve’s was introduced in 1981 by Blazier to primarily rate noise in offices/room acoustics. This methodology calculates a numerical rating based on speech interference and indicates any interference such as hissing, rumbling, or vibration.

SEL

Sound Exposure Level. The continuous SPL lasting one-second that would deliver the same sound exposure as an accumulated exposure determined over a sampling interval (RTime). SEL is typically determined with a 3 dB Exchange Rate, slow exponential time-weighting, and without regard to an Integrating Threshold.

SEL = ER log20RTIME 2L ⁄ ER dt dB

SPL

Sound pressure level. A ratio of one sound pressure to a reference pressure (See Reference Pressure on page 141). Because of the enormous dynamic range of the human ear, the ratio is calculated logarithmically by the formula below, where Lr is the reference pressure.

SPL = 20 log  L  dB ----

Lr

Models SE and DL

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Image 158
3M SE, DL user manual Room Criterion Curves RC, Sel