Location: Saskatoon, Saskatchewan, Canada
Owner/Operator: MLT Aikins LLB
MLT Aikins is a full-service law firm with 240+ lawyers serving Western Canada from offices in Winnipeg, Regina, Saskatoon, Edmonton, Calgary & Vancouver. The law firm recently moved its Saskatchewan law offices to a new location on the 11th and 12th floors of the east tower at 409 3rd Avenue South at the River Landing development in Saskatoon.
HGC Engineering was contracted to assess concerns of low levels of speech privacy between various areas in the new offices, such as between the reception area and several adjacent boardrooms; between boardrooms; between boardrooms and adjacent private offices; and between offices vertically on the 11th and 12th floors.
The acoustical aspects that influence the perceived acoustic quality of meeting rooms include sound insulation, room acoustics (in particular, reverberation time), and background sound levels. These aspects were measured during our site visit. In addition, standardized sound insulation tests were conducted between adjacent spaces.
Acoustical Design Targets
There are no requirements in the Canadian Building Code for the sound isolation rating of demising walls between office spaces, and no specific targets were provided by the client. We therefore relied on our own experience and understanding to develop suitable criteria in determining the acoustical performance of the spaces in questions. For example, a rating approaching NIC-50 provides reasonable separation for meeting rooms with AV capabilities. For office-to-corridor/reception, constructions should provide NIC-40 (preferably 45 or higher) to help prevent eavesdropping.
Standard Test Method for Measurement of Airborne Sound Insulation in Buildings
Standardized field tests to determine ratings of the partitions were performed in general accordance with the protocols outlined in ASTM standard E336-97, “Standard Test Method for Measurement of Airborne Sound Insulation in Buildings.” These tests are performed by placing a sound source on one side of the assembly under test and measuring sound levels in the “source” room, and in the receiver room on the other side of the subject partition. Background sound and reverberation measurements are also taken which are used along with the room geometry to calculate the ASTC rating according to the ASTM standard E413-10, “Classification for Rating of Sound Insulation Class”. In cases where the receiver room is not clearly definable (for example, corridors or small rooms), Noise Isolation Class (NIC)-values are generally quoted, which more simply report the sound level difference between spaces.
Sound Intensity Measurements
Diagnostic sound intensity measurements were also conducted to identify the paths with the most significant contribution to sound transmission which can help to identify acoustically weak components. Sound intensity measurement instrumentation has a high inherent ability to reject extraneous sounds originating from outside the measurement control-volume, and can therefore help separate the sound emitted by each component.
Evaluating Noise Transmission Levels Between Office Spaces
Following our visit, the sound measurement data was processed and additional analysis applied to determine and evaluate the level of noise transmission between each pair of spaces. The measured reverberation levels and the noise transmission performance were then compared to typical acceptable limits for each space. Generally speaking, the primary sound transmission mechanisms were found to be at the interface between the demising walls and the exterior walls, as well as through gaps around various doors. Preliminary options or conceptual recommendations were then proposed which would help mitigate sound transmission between spaces and increase acoustical privacy and speech intelligibility as required in meeting rooms and offices.
Acoustical Engineering Services Included:
- Assessment of Speech Privacy between Offices, Meeting Rooms and Reception/Common areas
- Measurement and Evaluation of sound insulation, room acoustics (reverberation time), and background sound levels.
- Standardized field testing to determine partitions ratings in accordance with ASTM standard E336-97, “Standard Test Method for Measurement of Airborne Sound Insulation in Buildings.”
- Calculating the ASTC ratings in accordance with ASTM standard E413-10, “Classification for Rating of Sound Insulation Class”
- Sound Intensity Measurements
- Noise Control Recommendations