Steve Yorke, Lead Consultant – Acoustics
TTM is sometimes engaged to provide advice regarding reduction of sound transmission within a building. This can be between two adjacent rooms where one is generating noise and the other is sensitive to the intrusion of noise. For example, a reception area next to consultation rooms, a workshop next to an office, or a server room next to work desks. The intrusion of unwanted sound (‘noise’) can be distracting and/or annoying and interrupt work productivity and affect wellbeing. Speech privacy is a related aspect although not the subject of this article.
The Association of Australian Acoustical Consultants (AAAC) publishes the ‘Guideline for Commercial Building Acoustics’, which provides advice on the level of required sound reduction between two spaces depending on the level of source noise and the receiving room’s level of noise tolerance.
Table 3:‘Guideline for Commercial Building Acoustics’, AAAC
Guidance on levels of noise generation and noise tolerance for various types of rooms is also provided.
Table 4,‘Guideline for Commercial Building Acoustics’, AAAC
This information can be used to determine the required sound reduction (Rw) of the room envelope, for example, the room’s walls and ceilings.
Some common design aspects to consider to achieve the required sound reduction between adjacent spaces are:
- Extension of the dividing wall/partition to full height past the ceiling to the underside of the floor slab or roof above. Full height walls and partitions are preferred used when the partition performance exceeds Rw
- If walls are not extended full height, then the ceiling itself will need to achieve the required sound reduction rating or the use of ceiling void barriers.
- If glazing is used as part of a wall, both the glazing and the glazing framing are to achieve an adequate sound reduction rating which is based on the relative size of the glazing component(s).
- If a door is part of the wall, the door and its seals must achieve an adequate sound reduction rating. Noting that door seals will have only limited sound reduction performance.
- Any penetrations in the dividing wall for electrical or mechanical services must be fully sealed. Electrical services such as GPOs will need to be offset by a minimum of 600mm on each side of the wall and may require an acoustically rated backbox if the partition is rated at Rw45 and above.
- Mechanical services (eg. air conditioning) may bridge both rooms and provide a ‘crosstalk’ path for noise to travel between rooms. Crosstalk paths need to be considered and appropriately treated such as with a crosstalk attenuator, or solid metal acoustically lined duct sections or bends. Flexible ducts should not cross or penetrate partitions. If possible mechanical service penetrations and ducts should enter the acoustically sensitive space from the partition containing the door, as this partition is already compromised by the door itself.
If you wish to obtain or discuss any further information on building acoustics matters, please get in touch with the TTM team.