Thalheimer has dealt with ventilation noise many times before in projects as small as a pizza oven fan causing annoyance inside an adjacent condo, to as large as multi-billion dollar tunnel ventilation systems to ensure they meet NFPA 130 and 502 standards for emergency communication intelligibility. He has developed an empirically-based fan noise prediction model to estimate fan noise levels inside spaces, and has recommended numerous methods to attenuate fan noise including the use of silencers, housing lagging, alternate fan operating parameters, and new grill design.
Example projects involving industrial and/or power plant noise evaluation and control include the following:
- Sumner Tunnel Jet Fan Ventilation Noise, Massachusetts Department of Transportation, Boston, MA (2015) – Developed sound power level specifications for new jet fans being installed as part of the Sumner Tunnel rehabilitation project. Modeled in-tunnel noise levels to ensure that jet fan noise would not exceed 92 dBA five feet above the pavement in accordance within NFPA 502.
- Midtown-Downtown Tunnels Jet Fan Noise Compliance, Virginia Department of Transportation, Norfolk & Portsmouth, VA (2015) - Developed an analytical noise prediction model to evaluate anticipated contractor compliance with submitted jet fans for the Elisabeth River Midtown and Downtown Tunnels. Predicted jet fan sound pressure levels at a position 5 feet above pavement using sound power emissions from proposed jet fans, and evaluated the results against the project specifications limit of 92 dBA. Developed project position paper to justify relaxing tunnel interior noise limit to 92 dBA in accordance with NR85 criterion and NFPA 502 guidelines. Performed jet fan sound power level tests inside the DTWB tunnel to verify sound power data provided by the manufacturer. In-situ tests were performed using a B&K 4204 reference sound source in accordance with ISO Standard 3747. Reverberation time was also measured in the tunnels, using a B&K 4224 loudspeaker and white noise source, to enhance the accuracy of PB’s in-tunnel noise prediction models. Visited the jet fan manufacturer (Clarage) to critique and instruct how to perform sound power level measurements correctly.
- Baltimore Red Line Station Ventilation Noise Assessment, Maryland Transit Authority, Baltimore, MD (2014) – Performed a community noise evaluation of ventilation fans proposed for inclusion in five new Red Line transit stations in downtown Baltimore. Predicted ventilation fan sound power levels emanating from air shafts using the TAP acoustics model and propagated fan noise levels to nearby community receptors using the Cadna-A model. The results were evaluated for compliance with the project’s noise criteria established per FTA procedures, and the insertion loss of fan silencers and shaft surface areas requiring acoustical absorption were determined. Also predicted ventilation fan interior noise levels at terminal dampers in the patron platform area for the Inner Harbor Station. Interior fan noise levels were predicted using the TAP model, with the results evaluated for compliance with the project’s 85 dBA criterion for understanding unamplified speech during an emergency and 92 dBA to avoid long-term hearing damage for station employees.
- East Side Access Project Ventilation Buildings Fan Noise, New York Metropolitan Transit Authority, New York City, NY (2011) – Performed review of ventilation fan noise studies (done by others) for eight ventilation facilities associated with a new transit rail line through New York City. Evaluated the proper identification and determination of relevant noise criteria limits, computed insertion loss values expected from installation of fan silencers, estimated noise reduction due to use of Pyrok absorptive treatment, confirmed that community noise levels would comply with FTA and NYC exterior criteria.
- Tunnel Jet Fan Community Noise Predictions, Central Artery/Tunnel Project, Boston, MA (2000) – Community noise prediction models were developed in order to evaluate potential CA/T Project tunnel jet fan noise consequences in various areas of Boston. The noise models were based on laboratory tested sound power source spectra for the given fans, and took into account tunnel wall surface absorption, intervening boatwall barriers, and the insertion loss characteristics of applied silencers. The predicted noise level results were evaluated within the model for acceptability against the City of Boston's Noise Code. The noise model was featured in a paper given at the 2001 AWMA Conference.