3M SE-400 user manual Spl/Las

37

Appendix B

Relative response (dB)

Burst duration, t (milliseconds)

Figure B-3:Fast response to a tone burst

SPL/LAS

Sound pressure level. A ratio of one sound pressure to a reference pressure. 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.

 L		d B
SPL = 2 0l o g----
 Lr	

Threshold

An SPL value that defines a lower level of acceptable values. Only SPL samples that exceed the threshold are used in some calculations.

Upper Limit (UL)

The total time during a study that the SPL exceeds the Upper Limit meter setting.

Sound Examiner SE-400 Series