From HBR [2]:
> 3. Mask the sound by increasing background noise. It seems counter-intuitive, but adding more sound to an environment can actually make it seem quieter. Research suggests that noise itself isn’t distracting, but unwanted speech noise is. However, words that are incomprehensible are less likely to be distracting. By adding a continuous, low-level ambient sound to an environment (such as white noise, which sounds similar to the sound of airflow), sound masking can help make conversations for listeners that aren’t intended to hear them unintelligible, and therefore much easier to ignore.
It also raises the interesting point as to why I find it so easy to work at coffee shops in foreign countries.
[1]: https://en.wikipedia.org/wiki/Sound_masking
[2]: https://hbr.org/2015/03/stop-noise-from-ruining-your-open-of...