Strutt Help

Strutt|Building Acoustics|Enclosure calculates the sound power radiated from an enclosure, given the row of sound power levels (L_w), the row of transmission loss values (TL) and the enclosure conditions, and inserts the results into the active row on the worksheet.

Constant C is a factor accounting for internal enclosure conditions, and has the following octave-band values:

Enclosure Internal Acoustic Conditions	63 Hz	125 Hz	250 Hz	500 Hz	1 kHz	2 kHz	4 kHz	8 kHz
"Live"	18	16	15	14	12	12	12	12
"Fairly Live"	13	12	11	12	12	12	12	12
"Average"	13	11	9	7	5	4	3	3
"Dead"	11	9	7	6	5	4	3	3

The following guidance is given as to selecting the acoustic conditions within the enclosure:

• Live: All enclosure surfaces and machine surfaces hard and rigid
• Fairly Live: All surfaces generally hard, but some of panel construction (sheet metal or wood)
• Average: Enclosure internal surfaces covered with sound-absorptive material, and machine surfaces hard and rigid
• Dead: Enclosure internal surfaces covered with sound-absorptive material, but machine surfaces mainly of panels

References:
Bies and Hansen, Engineering Noise Control, Second Edition, E & FN Spon, London 1996