Introduction: Binaural Listening Device
I have always been interested in
telepresence systems since university and developed a simple one for my Masters.
A telepresence system provides the illusion of presence. This can be used to help you be present in a business meeting in a foreign country while sitting in your office without needing to travel. They can make you aware of a remote operated robot's surroundings and allow you to interact with it's environment.
I would like to get into developing these system but a lot of they are generally expensive, complicated and I have very little experience with electronics. However there are very basic and simple systems that can recreate the illusion of presence. One example I found was the “Virtual Barber Shop” on Youtube in which the video creates the illusion being inside a barber shop. The Virtual Barber Shop uses the binaural recording technique which uses a dummy head with microphones inside artificial ears to record audio. The user then listens to the audio with headphones where the user's brain filters the sounds which allows them to locate the source of sounds.
This system was very simple to manufacture and will act as a base for future telepresence robots as I gain a better understanding on electronics.
Step 1: Items
For the binaural audio recording system you require the following:
- Dummy head (I used a polystyrene head). You want to ensure you have a dummy head that is the same proportions to a human head as this will help the robot replicate how you hear sounds.
- Silicone Ears (these can be purchased from Amazon or you can make them yourself)
- Plastic tubes (to act as ear canals)
- Wireless mic system (ensure it has 2 channels)
- 3.5mm Socket to 6.35mm Jack Plug Audio Stereo Adaptor
- Mono to stereo adaptor
- Screws x6
Step 2: Step 1: Preparing the Dummy Head for the Ears.
First thing you need to do is remove the ears that are on the dummy head. I used a wire cutter to remove the ears and then traced an outline of each ear at the side of the head.
Mark out the outline of the silicon ears on each side of the head as you want to create some grooves to house them.
After you create the grooves for the silicon ears you want to create a hole on each side to house the ear canals and microphones. This will allow the robot to pick up sounds like your own ear would.
Step 3: Step 2: Prepare the Dummy Head for the Cables
A hole was needed at the back of the head so that the wires from the microphones can be plugged into the transmitters. A circular file was used as it made it easy to break the polystyrene down and create a big enough hole quickly. Once the hole was big enough the cable from the microphones were passed through the ears and out fed out the back of the head.
Step 4: Step 3: the Ears
With the ear canals and microphones in place it is time to insert the silicone ears. Place the ears in the grooves and line up ear holes in the ears and ear canal. Once the ear is in position secure them with screws.
Step 5: Step 4: Wiring
Connect the microphones into the transmitters of the wireless microphone system.
Connect the Mono to Stereo adapter into the receivers to combine the signals from the microphones into two channels so that ears listen to each microphone. Then connect the adapter into your amp
Finally connect your headphones into the amp and now you can listen to the sounds your robot is recording.
Step 6: Step 5: Chair Assembly
For my dissertation I connected this robot onto a motor and connected the motor controller to a chair so I can control it remotely.
Step 7: Step 6: Drive System of the Chair
I used an ordinary office chair and salvaged a geared drive system and stepper motor from a previous university project that was sitting in the workshop gathering dust.
I then designed a base plate that would hold the control box of the drive system. The gears and motors would be attached to the centre column of the chair in order to rotate the chair.
Step 8: Step 7: Footrest
In order to prevent the users feet from trailing along the floor I designed a footrest that would be attached to the chair.
The footrest frame was made out of iron tubes that were cut with three short and two long pieces which were bend into shapes that would hold the footplate. The top short bar was inserted into a bush with a rotary pin attached to it allowing the bar to spin so that the user can alter the height of the footrest. The bush was welded to the collar that connects the base to the seat of the chair. The lower short bar was welded to the long bars and a footplate that was constructed of an aluminium plate to keep weight to a minimum. The third short bar was welded to the footrest frame to increase strength but also to support an extension spring that was attached to the base of the seat.
Step 9: Step 8: Controls
Th chair and robot would rotate simultaneously to help locate sounds and help improve immersion. I was trying to recreate that the chair was the robot and you were sitting inside the head.
The chair and robot were controlled by two mirco switches located in the armrest which were linked to the robot motor and chair motor. Obviously in future projects I would develop a robot to be controlled wireless but I did it this way to save costs.
Step 10: Conclusion
This was a very basicsystem and I developed it for my Masters degree. I wanted to record this for future reference for when I get enough cash to develop a personal system. It was a cool experience being able to localise sounds without even being there. However seeing a polystyrene head silently rotating to face you was rather creepy. I would like to incorporate this type of technology into a rover I want to develop.