The invention would be most useful in noisy environments where alerts might otherwise go unnoticed or unheard. The system could also serve to automatically lower iPhone ringtone or notification volume in quieter situations.
The patent details an Apple Watch using its microphone to listen to ambient sound at regular intervals or when triggered to do so by a host device. Using the data collected, the Watch analyses the difference between the background noise and the alert audio level, and makes a volume adjustment accordingly.
The system is also able to work out the iPhone's orientation and location in relation to the user's body, including whether the handset is tucked in a pocket or stowed away in a bag, in order to account for physical sound barriers.
In one example, an iPhone sends a notification audio signal to the Watch before playing an audible alert. The receiving timepiece analyses the wave signal and compares it against a stored reference signal based on ambient noise samples. Through a combination of sound threshold analyses, the Apple Watch then sends the appropriate command to raise or lower the iPhone's output volume.
The invention could also be used to filter audio signals received by voice-activated control functions -- for example, by increasing the physical distance that a user can successfully activate Siri using the "Hey, Siri" spoken command.
Apple has researched the use of sound sensors before as a possible accompaniment to existing light sensors in its devices. However, ambient sound monitoring is now an established technology in the consumer space, for instance in several auto-adaptive noise cancelling headphones, suggesting implementation of the feature in Apple products could happen sooner rather than later.