How does Hodr Engine Work?

Hodr Engine is a user interface that makes development an accessible process.

Overview of Hodr Engine

Hodr Engine is an accessible spatial audio engine for users to create and explore sound-based environments. The user works within a top down grid, where sound objects can be arranged and customised to define their position and behaviour within the soundscape.

During development, the project can be rendered into a first-person audio experience. This lets the user explore the soundscape, hearing sounds rendered using lifelike binaural sound as they navigate the environment.

Once complete, the project can be packaged into an application that can be shared by the developer.

The Hodr Engine user interface showing a grid containing some objects that have been placed there by the user. Along the second row are two houses and below is a car. Further along the row the houses is a tree. All of these are written as words and you can see a rotation marker in the grid spaces. At the top right of the grid it says the user is 'Carrying tree'. This information is read out by a screen reader.

Designing a soundscape

The design process begins in a top down grid. Each position in the grid represents a location in the final environment.

Users can place sound objects onto this grid either by importing their audio files or by selecting sound effects and music from the built in Hodr Engine library.

Environmental effects & acoustics

Users can apply reverberation and define the acoustic character of a soundscape, such as a spaceship cockpit, or an open forest with a grassy floor where sound is softened and scattered.

An image of the Hodr interface on a computer screen. The word 'Player' is written on a central grid space with the word 'canopy' in front. All around, the word 'Hills' is written. The word 'Moon' is in a left grid space and 'Sky' is in. a grid space near it.

Experiencing the project

Once the soundscape has been designed, it can be rendered into a first person perspective. The player explores the environment using keyboard shortcuts or a controller to move forward, backward, left, and right. As they move, the spatial audio updates relative to the listener in real time.

When the project is completed, the user can package it as an app to share as they wish.

As an accompaniment to the image of the grid above, this image shows the grid scene rendered. We are looking out of the cockpit of a spacecraft as we fly over a 3D planet surface with a large moon, a hilly landscape with a space background.

Accessible design

The Hodr user interface has been developed by registered blind software developer, sound designer, and founder of Immersion Sound Studio, Freya Shaw, who developed the interface using VoiceOver, VoiceOver built in screen reader.

The interface can largely be navigated via shortcut keys and is compatible with VoiceOver, allowing blind and sighted users to develop experiences that are accessible to both blind and sighted audiences.

Spatial audio

Using binaural audio rendering for headphones, Hodr supports spatial reverb for simulating different world environments, customisation tailored to the player’s head characteristics, and real-time head tracking for ultra-realistic motion effects. Hodr’s spatial audio engine is powered by the Signalflow library for digital signal processing and spatial audio.

A young man playing a computer game wearing headphones. His eyes are closed to depict an audio gaming environment.

Built in music & sound library

Hodr Engine includes a built in library of music and sound effects created by composition leads John Bailey and Curtis Stansfield.

Users can select from a range of pre composed music and sound effects, or combine these with their own audio files to build a soundscape.

Building the Library