6-10
During an intelligibility survey in an office building, an employee lobby area measured 0.60 CIS
intelligibility, failing the NFPA suggested 0.70. This room is characterized by tile floor, hard
walls, and one wall made up mostly of glass, see the figure below. The SPL is adequate at 79 dB
for an average background noise level of 47 dB.
Figure 6-13. Lobby Example
Lobby Example:
• Dimensions = 24’ L x 16’ W x 10’ H
• Flooring = Tile
• Ceiling = Acoustic Tile
• Walls = Three Walls of Finished Wood, One Glass
• Ambient Noise = 50 dB
Figure 6-14. Lobby Example
The following basic results are attained from the iTool:
• The iTool reverberation time calculator estimates a reasonable T60 time of 0.62 seconds.
• Using an Edge-to-Edge pattern, the resulting total number of speakers is 4 tapped at 0.25 W,
for a total of 1 W of audio power required.
Continued on next page
Applying the Methods, Continued
Example 4:
Lobby
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