Section: Software

Mobile Audio Language

Participants : Yohan Lasorsa, Jacques Lemordant.

MAUDL library

The MAUDL library (Mobile AUDio Language) [15] is an evolution of the ARIA library whose primary target was games on mobile.

Augmented Reality Audio applications use sound objects to create a soundscape. A sound object is a time structure of audio chunks whose duration is on the time scale of 100 ms to several seconds. These sound objects have heterogeneous and time-varying properties. In order to describe Interactive Audio (IA) contents, we created MAUDL, an XML language inspired by iXMF that is well adapted to the design of dynamic soundtracks for navigation systems.

MAUDL prevents audio information overwhelming through categorization at the declarative level and the use of priority queues at the execution level. This allows to take account of speed when walking, and rapid hand gestures when interrogating the environment for example. MAUDL can be used as an authoring time interchange file format for interactive mobile applications or as a runtime file format that is actually loaded through the web and played directly in the mobile. MAUDL is a cue-oriented interactive audio system, audio services being requested using named events and the systems response to each event being determined by the audio artist. The current version of the API supports iOS and further support for other mobile platforms (Android) is planned.

3D Audio Pointer

A virtual 3D audio pointer provides an intuitive guide to the user of a mobile application, reducing the need for cognitive work when compared to vocal instructions. We have built such a pointer using the MAUDL language. It gives the user the azimuth using HRTF spatialized audio cues, with additional hints taking the form of variations in the sound used. It allows to superpose other kinds of audio contents, such as voice while the pointer is active, to indicate distance for example. This audio object is suitable for different sorts of navigation systems, such as POIs browsers, self-guided audio tours, or predefined route following applications.