The main limitations of a sound masking system’s success are client expectations, and the proximity and loudness of the problem. 

Sound proofing

If a client’s expectations of sound masking include “sound proofing”, then they will be disappointed. Sound proofing is a different technology. Usually it includes absorption, blocking, damping, reflection, or diffusion.

Sound masking adds sound to a space. It is capable of improving speech intelligibility to the point that speech is unintelligible, however it is incapable of rendering speech inaudible without other acoustic treatments. Sound masking is also capable of improving a space so that intrusive noise is no longer obvious, but it is incapable of cancelling noise.

Loud noises

Sound masking is also incapable of masking loud noises. For example, it is impossible to mask a barking dog unless the masking is set to hearing loss levels (around 90dBA). 

Close noises

Sound masking cannot create speech privacy where the noise is very close by. For example, it cannot comfortably mask a private conversation in an open plan office if the conversation is happening in half a metre away. There are other acoustic solutions to these problems.

Additional acoustic treatments

Sometimes these limitations can be overcome by including additional acoustic treatments (eg, door seals), but sometimes they cannot.

One of scenarios where additional acoustic treatments created an optimal outcome is provided in the picture below, where door seals were added after the sound masking didn’t reach the required level of speech privacy. This was an expected outcome, and we were able to advise the client of the likelihood door seals would be needed. This small, inexpensive, adjustment created speech privacy without compromising the vintage aesthetic.

Conclusion

While sound masking is usually a useful and effective solution to most acoustic problems, there are some limitations. If in doubt, it is best to consult with a professional.