3D Sound and Binaural Audio
EarGames games make broad use of 3D Sound where appropriate, using a technology known as HRTF or Head Related Transfer Function.
HRTF works by applying sophisticated digital signal processing to a sound and then delivering that sound over headphones. The sound then has the apparent effect of coming from somewhere in 3D space around the listener, well outside the head of the listener.
The particular implementation of HRTF used by EarGames comes from QSound Labs, creators of Virtual Haircut, the most widely viewed 3D sound on the internet.
3D Sound vs Surround Sound
People sometims ask what the difference between "3D Sound" and "surround sound" is. With surround sound, you have multiple physical speakers that surround the listener. Most typically, that is limited to a flat plane, such as a 5.1 or 7.1 surround sound system.
3D sound does something different. Rather than rely on multiple speakers, 3D sound (sometimes called "HRTF" audio) uses only two speakers or headphones. By using fairly sophisticated digital signal processing algorithms, 3D audio attempts to duplicate how we hear in the real world and mimic that effect. For example, if a sound is over to your left, it will reach your left ear before it reaches your right ear. That's called the "inter aural time difference." It will also be a bit louder in your left ear than your right, because your head blocks the sound. That's called the "interaural intensity difference." A third things that is used is called the "pinna transfer function". That is what happens as sound coming from a particular location in space bounces off the folds of your out ear (the 'pinna') before entering your ear canal. Believe it or not, your brain can decode those minute reflections and use the information to help locate where the sound is coming from.
Games for the Visually Impaired
Although we don't necessarily make games specifically for the blind at EarGames, we are of course aware that sound-based games are natural candidates for many gamers who have visual impairments.
One thing that we were struck by was how many visually impaired gamers play games that are 100% tradtional video games, yet their audio was so well crafted that gamers are able to complete them purely by ear. Here are several interesting stories about sound games, 3D audio games, or traditional games that have been mastered by players who couldn't see the "video" part of the videogames.
The video game industry also has an organization, the accessibility group of the IGDA, dedicated to increasing accessibility in video games--that is, ensuring that when a developer builds a new game, they consider visual or other impariments in their design and implementation.