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[Alan Clayton]

I have been asked to quote on a Sound masking system. I have done these before in smaller offices, ie. 10,000 square feet, but this is 40,000 square feet. I have always done the traditional systems with up or side firing speakers above the ceiling. To make matters more complicated, the roof is peaked, with fire walls which partition the space above the ceilings. 3' of space at the walls, 26' in the center. There is also an 5000 square foot area that has 6" of Fiberglass insulation on top of the tiles. I ran a configuration program (Atlas) which came up with 150 traditional, up firing 8" 70v speakers. They have also mentioned they may want to use the system for paging (Not reccomended, I know)

So I have several questions:

Has anyone tried using fewer speakers at a higher SPL in a system this large? If so, what speakers did you use, and were there any ill effects?

Has anyone ever tried sound masking over a paging system? And related, what about using regular ceiling speakers, (particularly in the area with fiberglass on top of the tiles.)

Has anyone used the Voice Arrest system? If so what are your thoughts?

Any help is appreciated.

[Brad Weber]

So I have several questions:

Has anyone tried using fewer speakers at a higher SPL in a system this large? If so, what speakers did you use, and were there any ill effects?

Has anyone ever tried sound masking over a paging system? And related, what about using regular ceiling speakers, (particularly in the area with fiberglass on top of the tiles.)

Has anyone used the Voice Arrest system? If so what are your thoughts?

Fewer speakers at higher level wouldn't seem to be the same in terms of coverage and since the goal is to not be able to identify the source of the sound, coverage is important.
 
Sound masking and paging have somewhat disparate goals, they may relate to very different EQ, different zones, etc.  I guess they could be combined with the proper processing and routing capability, e.g. addressing each speaker or each different masking zone/paging zone/condition combination independently.  As far as using speakers in the ceiling, that goes back to coverage and getting coverage where you both don't identify the source or have changes in level for masking but still get good intelligibility for paging might require a large number of speakers.  Even if the speakers are above the ceiling aspects such as open return air grilles may have to be considered in order to kep from having noticeable local variations in the levels.
 
Just curious but is the masking part of a comprehensive speech privacy plan?  Sound masking is sort of the icing on the speech privacy cake and if the partitions, finishes, furniture layouts and even light fixtures don't provide a good base then it can get messy.  Simply adding masking to a space without addressing these other issues often leads to less than desirable results, so it may be best to at least know what kind of situation you're getting involved in.
 
I have not used the Voice Arrest system, but I'm not real impressed by the 'Direct Field Technology' discussion or animations, which seem to address both basic physics and practical considerations only as they may support their approach and to ignore any aspects that work against the 'Direct Field' approach.

[Karl Maciag]

I've had to use ceiling speakers before for a masking application.  There was not enough room between the drop ceiling and real ceiling to fit up or side firing speakers.  To maintain good coverage you will need a lot of speakers in the space,  providing a lot of overlap of coverage between them.  Also,  I used two different noise generators in the system and assigned them to every other speaker.  This made sure the noise was not in phase from speaker to speaker, which minimized that phasing sound you hear when walking though a space with the same sound source coming from two sources.  Atlas has a great white paper on sound masking, that gave me that tip,  and some other great ideas to approach those systems.

I wouldn't recommend doing paging in the system even if you are using traditional ceiling speakers.  If you have to,  try to get the paging signal above the noise without using any sort of ducking or else the noise will become noticeable...

[ProSoundWeb Community]