Myth: Sound Masking Can Help Solve Voice Intelligibility Problems

When it is hard to hear speech in a room, there are several things that can address that issue. Typically, the primary task is to reduce the echo/reverberation in the space. This is accomplished with absorption and diffusion treatments.

Introducing sound masking is a tool to improve privacy, so that voice or other sound content cannot be easily understood. Sound masking by its very design decreases voice intelligibility, making communications within the room more private. When the listener can make out the conversations from adjacent spaces it can be a continuous and unwanted distraction. Even a disciplined worker cannot entirely block the analysis of incoming information. We know this is true – if your name is spoken, your hearing recognizes that content. The background mental processing simply cannot be turned off, and that processing of background sound has a significant cost in mental energy, stress, and distraction.

Care must be taken when there are both privacy and voice intelligibility concerns in the same space. While sound masking can be quite effective to enhance privacy and minimize distractive noises, it will reduce voice intelligibility. Masking is no silver bullet. A careful integration of acoustical treatments with electronic masking technology is often essential to get both reasonable privacy and good voice intelligibility for a space.

Glossary of Terms
Echo is the delayed arrival of a sound following its initial arrival to the listener. Sometimes the term is used to label sounds that are far enough in time from the initial sound that they can be recognized as the initial sound delayed.
Reverberation is the accumulation of multiple delayed sounds over time. Part or all of the reverberation may be unrecognizable as being initiated from the initial sound.
Sound Masking is a system of introducing non-distracting masking noise to reduced speech intelligibility and enhance privacy.
Voice Intelligibility indicates the ability of a listener to understand voice content in a given acoustic environment.

Chuck Chiles, Director of Technology, Unika Vaev Acoustics