The first beta of iOS 14 includes the ability to set up notifications that trigger if the iPhone hears specific sounds, an accessibility feature that could help alert hearing-impaired users to fire alarms or dogs barking nearby.

Apple’s unveiling of iOS 14 and iPadOS 14 at WWDC covered a lot of new features, but not everything was revealed in the presentation, nor in supporting documents. One new feature was spotted without the fanfare, but may have a big impact for some of Apple’s customers.

Shown in a video on Reddit by user “u/Jsmith4523” on Monday night, the Sound Recognition feature is an audio detection system in the iPhone that can listen out for specific sounds. Once heard, the iPhone then displays a notification on-screen advising it has heard a sound, and identifying it.

The list of sounds it can pick up include animals like cats and dogs, household sounds including running water and appliances, and doorbells and door knocks. The system is also sophisticated enough to listen out for people shouting and baby cries, and can even distinguish between alarm sounds for fires, smoke, and sirens.

Notifications are displayed with the “Sound Recognition” title, along with a brief description of what was heard.

Descriptive text for Sound Recognition advises the iPhone “will continuously listen for certain sounds, and using on-device intelligence, will notify you when sounds may be recognized.” It goes on to highlight how it should not be relied upon in cases where the user may be harmed or injured, emergency situations, or for navigation.

The function is likely to be welcomed by deaf iPhone users, as well as those hard of hearing, as it will give a visual and tactile alert to largely audio-only events.