A corporate office client in Tampa FL was experiencing conversation sound transfer in their closed offices. The offices were designed with a proprietary modular wall system (STC range 31 – 48) and Armstrong Calla ceiling tiles (CAC 35) with a Lencore sound masking system is in place. Prior to determining what modifications needed to be taken to improve office sound privacy, sound testing and analysis was completed.
Specifically, Commercial Acoustics was brought on to perform Airborne Sound Tests (ASTC) in accordance with ASTM E366 using a white noise speaker and Class 1 SPL meter. This repeatable test allows the general contractor and tenant to determine how much noise each wall assembly type is blocking, and therefore what mitigations need to be completed and how to proceed on future buildouts.
Per a discussion with staff on site, audible speech was readily heard between adjacent office spaces, including not just muffled voices, but clearly-heard and articulated conversations.
Results:
| Wall Type | ASTC Score |
| Initial Wall – No Batt | 28 |
| Initial Wall – With Batt | 31 |
| Drywall Partition – No Batt | 36 |
Table 1: Summary of Wall Types Tested and Associated ASTC
As you can see in the chart above, the standard Drywall system performed 5-8 points higher than the modular system in question, even without batting!
Office Acoustic Solution:
Office Sound Masking was also implemented. The Lencore Sound Masking system was used, and levels were measured 4’ off the floor at 49 dBA. This is considerably louder than a standard sound masking system within a closed office-space. While continued volume increase may improve speech privacy, it will also create a distracting and disruptive office environment.
The client is now strongly considering moving to drywall partitions for sensitive areas – around private and executive offices. If higher STC levels are preferred, additional layers of drywall or specialty soundproofing products may be required.
Commercial Acoustics continues to offer consulting and product solutions for clients around the United States. For more information, contact us today.
