what is the dBA level within this space?

[scattergunner]

I have a Process Room (approx. 90'x48') that has a Lab space (24'x16'-2&quot in the northwest corner of the room. the 90' and 24' dimensions run north/south. The Procees Room has a house vac (79 dBA) and wet vac systems (75 dBA) with within 20' of the Lab space. The wall that separates the Lab from the Process space is a 3-5/8" metal stud wall at 16" oc with 5/8" gwb both sides with acoustical insulation. I'm assuming an STC rating of 47. the height of the wall is approx. 22'-2" high or open to structure above. How much of the dBA is knocked out by the wall and what would be the approx. Dba level within the Lab space?

 

[Hatch]

The final sound level in the lab will be determined more by the gap at the top of the wall rather than the STC or transmission loss characteristics of the wall. ie. The sound is more likely to travel over the wall rather than through it.

What is the size of gap at the top of the wall?

In order to do a complete calculation the following information is required.

Description and area of the floor, wall and ceiling materials (to determine the acoustic absorption coeficients).

Sound level and location of the noise sources. The sound level should be in octave bands not just an overall level which is what you quoted.

Size of the gap at the top of the wall.
Size and type of doors and windows.
Are there any ventilation openings?
Are there other noise sources?
What are the proposed activities in the lab?

Without calculations, I would guess that your lab sound level is going to be approximatel 15 to 20 dBA less that the sound level outside the lab. If the noise sources are tonal (highly likely) then your resultant sound level of around 60 dBA may or may not be a problem depending on the proposed activities in that room. Is it an office too? or is just a lab work room. Are there any phones? Are there any other noise sources such as ventilation hoods?

The activities in a room are used to establish a target noise level such as PNC50 or NC50 etc.

Hope this helps, as you see there are many things to consider in noise control design.

 

You must calculated the insulation of your wall, doors, windows and every kind of surface that you have, then you must calculated the complex partitión by octave or 1/3 of octave(Leo Beraneck Noise and vibration control) and then you put this as your general insulating and sum the DBA scale.This are the preliminar calculus, then you must put a level of reference like 100 db and sum the DBA scale transform this 2 colums in energy.i can calculate this is very easy or i can send you and email.

The absortions coeficient or the materials that you have in your lab are necesary for the reverberation time inside of the lab and how much of the energy is absorted inside of the lab and carry out by the walls or surfaces countorns, are two proccess one is the insulation (indoor and outdoor)and the other is the level that you need inside of the lab.

marioa@netline.cl

marioa@netline.cl