This case study gives a detailed look into a recent noise study completed by SM&W acoustical experts analyzing a curtain wall at a New York City high rise, multi-family building.
A new 65-story high rise, luxury apartment building located in Manhattan was completed and occupied in 2018. Within several weeks of occupancy, the residents were complaining of a cracking noise from the mullions of the curtain wall façade. SM&W was contracted by the building’s management firm to investigate the source curtain of the wall noise by performing a noise study.
It was the opinion of the curtain wall contractor that the cracking noise was due to thermal expansion. The building management team’s opinion was that the noise was caused by structural issues and was most disturbing to residents during high wind events. Both believed the noise source was the vertical mullions joints located at the top and bottom of the mullions where they were connected to the slab edge.
SM&W leased a Norsonic Model nor848 acoustic camera (see figure #1 below) and set up a week-long study of the curtain wall to determine the source, frequency, and during which weather events that the noise occurred. The information obtained would be used by the building management team and curtain wall contractor to determine a solution to the noise issue.
Figure #1: Norsonic Acoustic Camera
The Norsonic acoustic camera consists of a one-meter diameter dish with microphones embedded in the dish. The dish is pointed at a noise source and noise is recorded, a video recording is generated the noise source and is pinpointed and displayed as an infrared image. This measurement device is typically used in heavy industries such as power plants or engines to pinpoint vibration or noise. SM&W saw an opportunity to utilize such a device for this noise study.
The acoustic camera was set up within several unoccupied apartments (see figures #2 and #3 below).
Figure #2: Robert Donovan with Acoustic Camera Set-Up
Figure #3: Acoustical Camera Set-Up and Curtain Wall
Our study showed that the curtain wall noise occurred in several unexpected locations and was not confined to the vertical mullions as shown in the figures below.
Figure #4: Noise Source Location in Curtain Wall
Figure #5: Noise Source Location in Curtain Wall
In addition, our study established that noise happened on good or bad weather days and therefore was not solely due to thermal expansion or structural issues, but a combination of both. This information has proven very useful to the curtain wall contractor and building management and a new direction in the curtain wall noise mitigation was devised based on our investigation.
This project exemplifies SM&W continued commitment to finding innovative ways to serve the needs of our clients. We consistently go the extra mile to ensure a successful project with cost effective and prudent approaches.
