Apple has been researching software solutions that would tap into a user's Apple Watch to intelligently adjust an iPhone's alert volume on the fly, by monitoring and comparing ambient sound samples.
Filed for with the United States Patent & Trademark Office (USPTO) back in 2014 and published on Thursday, the patent application titled “Volume control for mobile device using a wireless device” outlines volume control adjustments by having a Watch's built-in microphone sample an alert generated on an iPhone to “detect a distinct contribution corresponding to the audible alert.”