Smartphone-Based Auditory Motion Stimulation for Hemispatial Neglect: Development and Usability Study

Neglect radio smartphone application was designed to fulfil the following functional requirements:

1. Streaming of web radio stations.
2. Adjustable movement speed of the sound source (5–40°/s; default 10°/s). This range was chosen based on pilot testing to ensure the motion is perceivable yet comfortable for listeners.
3. Integration of spatial audio via HRTFs.
4. Multilingual user interface and content (initially German, French, and English).
5. Region-based station selection to ensure culturally relevant material.
6. Availability on both iOS and Android devices.

Based on the functional requirement 6, it was decided to use the Unity3D 5.0 (Unity Technologies) programming environment for application development, allowing to deploy the frontend application to both Android and Apple smartphones. Also, Unity3D provides a spatial audio function using the HRTF method. PhP (8.3) and SQL are used for the backend with user management function and daily usage duration storage. (Figure 1) shows the main user interface of the Neglect Radio application. The source code for the frontend (Unity3D) and the backend (SQL, PHP).