The application runs in the background of your phone, and once enabled will constantly record sound picked up by the phone. If something memorable occurs, the phone’s owner can easily save the audio file of the moment in question. Otherwise, the app will constantly delete rather than archive the captured data to minimise the storage space required.

The free version of the app only offers twelve seconds of recording time. However, those willing to pay €1.79 can get up to 5 minutes of recording time, with the ability to set other specific 'buffers' of 30 seconds or 1 minute of recording. 

Sound files can be renamed and shared via email or social network. The developers estimate that a full iPhone 5 battery charge will last for 12-15 hours when the Heard app is open and recording alongside normal phone and app use.

Developers Faalsa Labs recommend the app as a method for capturing spontaneous moments, recording important school or work information and to ‘expose bullying and verbal abuse’.

However, Heard is also likely to raise privacy concerns given the nature of an always-on recording software designed for mobile phones. The developers have attempted to address these issues by including a large red banner on-screen whenever the app is recording, and the need to open the app to ‘save’ any captured audio.