Acoustical Design
Before diving into our workplace scenarios, let’s first outline the two central concepts we’ll be covering. Speech intelligibility is our ability to communicate clearly and understand others well within a space, whether physical or virtual. Speech privacy, on the other hand, is when we want to obscure the ability to hear and understand well, preserving some degree of privacy in a conversation.
Depending on the space, speech privacy can vary from normal to confidential. Both speech intelligibility and privacy are defined as “freedom from distraction” where conversations nearby are audible and intelligible, but they should not distract someone absorbed in their work. With confidential speech privacy, conversations may be occasionally audible but they are not intelligible.
These concepts are influenced by the three tenets of acoustical design: Absorption, Blocking (or Isolation), and Coverage. Known as the “ABC’s of acoustics”, they guide the selection and implementation of our strategies to create environments that are conducive to communication, comfort, and well-being.
The ABC’s of acoustics
Sound absorption is achieved through the selection of room finishes. Absorption involves reducing the reflection of sound waves within a room. Excessive reverberation, caused by sound bouncing off hard surfaces like walls, floors, and ceilings, can degrade speech intelligibility, increase background noise levels, and create an uncomfortable listening experience. Sound absorptive surfaces such as acoustic panels, ceiling tiles, drapes, and carpets reduce reverberation and noise build-up, enhancing acoustical comfort and both speech intelligibility and privacy.
Blocking, also known as isolation, focuses on preventing the transmission of sound between different areas or rooms. Unwanted noise from adjacent spaces, outdoor sources, or mechanical systems can disrupt activities and compromise privacy. To mitigate this, the use of carefully designed constructions can effectively block the sound and provide the desired degree of speech privacy.
Sound coverage or masking refers to the use of elevated background noise levels, where the noise spectrum is shaped to specifically mask speech frequencies and provide more privacy. Suitable masking noise should be provided by a well-tuned electronic sound masking system as opposed to relying on environmental noises like mechanical systems serving a building. Acoustical design considers factors such as room geometry, and strategic placement of sound masking systems to optimize sound distribution and minimize variations in volume and clarity across different listening areas.
Auralization Scenarios
Environment 1: Open Office
Environment 2: Meeting Room
In closing...
All spaces have unique architectural characteristics, and all occupants have unique expectations of acoustics in their environment. Therefore a universal recipe for great office acoustics is not possible. Nevertheless, these concepts and listening exercises are useful by raising awareness of the importance of an intentional acoustic design.
