Yes, you read the title correctly. In this post we discuss a technique of adding noise to a call in order to improve its quality. Along the years, we published many posts discussing techniques to improve voice quality mainly by removing noise and echo from the calls, for example take a look at the following post elaborating on the expected functionality from a noise cancellation app.

But, removing noise and echo is not the complete story. There is a complementary technique in which noise is added to improve call quality. Initially this idea might sound absurd but it is not. This technique is based on understanding how the human brain works. Imagine listening to a call in which there are sudden occurrences of street noise vs. listening to a call that has a constant low white-noise background. Which one would you prefer? Most people will prefer the latter call as our brain adapts to the constant white-noise and can easily filter it out.

Another example for using this technique might be a call center environment in which adding low white noise masks some of the annoying volatile ambient noise in the call center.

One might argue that if all the ambient noise was completely removed in the first place then there is no need to add any white noise but this argument is not accurate. When you are making a call, if you hear complete silent from the other side for few seconds you might think that the call was terminated but if you continue to hear low volume white noise you know that the call is in progress and simply the far-end person is not talking.

In audio processing there is a professional term for this kind of noise that is added to the call. It is called “comfort noise” and indeed you might find that adding some “comfort noise” makes the call more comfort…

To conclude, echo and noise cancellation remain a critical factor in the journey to achieve high quality voice calls but in addition we should not forget a complementary technology called “comfort noise” that might be useful as well.