Ideas and EngineeringMIT

Researching Hearing TO "See" like a Bat

Through a class that I am taking at MIT I got really interested about our senses.
The class is called Networked Cultures: Collision – Body vs Network (

So, I started to…

Research HEARING:

Hearing (or audition) is one of the traditional five senses. It is the ability to perceive sound by detecting vibrations via an organ such as the ear.

In humans and other vertebrates, hearing is performed primarily by the auditory system: vibrations are detected by the ear and transduced into nerve impulses that are perceived by the brain (primarily in the temporal lobe). Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation.

Hearing in animals

Not all sounds are normally audible to all animals. Each species has a range of normal hearing for both loudness (amplitude) and pitch (frequency). In species that use sound as a primary means of communication, hearing is typically most acute for the range of pitches produced in calls and speech.

Frequencies capable of being heard by humans are called audio or sonic. The range is typically considered to be between 20Hz and 20,000Hz. Frequencies higher than audio are referred to as ultrasonic, while frequencies below audio are referred to as infrasonic. Some bats use ultrasound for echolocation while in flight. Dogs are able to hear ultrasound, which is the principle of ’silent‘ dog whistles. Snakes sense infrasound through their bellies, and whales, giraffes and elephants use it for communication.

That got me to think about the last Batman movie and ultrasonic hearing of bats…

So you might think the Bat-Pod is the coolest gadget Batman has:


The Bat-Pod’s forward-swooping design allows the rider to steer with his shoulders. Currently only one stuntman in the world has the skills to drive it.
Courtesy Warner Bros. Pictures /TM, © DC Comics

BUT, here is the actually most amazing device idea:

3-D Sonar System

Since the Joker does not have a lair or a base, Batman must track the constantly mobile madman through the streets of Gotham. To do this he uses a cowl-mounted sonar device that triangulates the baddies‘ cellphone signals and then renders the sound of their communication into a 3-D visual map.

So, the Joker is on the loose, he’s a hard man to track down and time is of the essence. Well, if you’re Batman you hack every mobile phone in Gotham to create a 3D sonar image of the city. Then, if his voice is picked up you triangulate his position Oh yeah, and the map can be fed straight into your cowl. Slightly unethical, but ace.

Video of the device through the sight of the viewer:


So, using Cellular Phones or another technology one could create 3D images of our surroundings, cities,…

To start this I created this FACEBOOK GROUP and REDWIRED GROUP (Austrian Social Network) to discuss the issues that might arrise, but also the positive sides of a device: It could be something interesting to be developed for blind people.

Real-World Counterparts, so far: Lidar and Sonar

Usually utilizing lasers, a Lidar system measures reflected light to find the range, dimensions and other properties of far-off objects. Sonar, of course, is the technology of bouncing sound waves off faraway objects to get a realistic picture of where those objects are. Combine the two, and you’ve got the 3-D system Batman uses to hunt his quarry.

Physical Boundaries still to be investigated

comment from

OK, I know it’s only a comic book movie, but still: sonar cell phones?

Work out the details. Let’s assume it is possible to force anyone’s cell phone to become an echo transponder (it maybe possible for all I know). The ultrasonic beep would have to be generated on the phone—cell phone transmissions have a notoriously low range: less than 10 kiloherz (kHz). The human ear can usually hear up to 20 kHz, and some people beyond that.

If the cell phone speaker can manage to generate the ultrasonic beep because Batman’s software completely took over the codec, then you still got problems. The sound goes out, and we’ll be nice and pretend it actually forms a nice sweeping cone, but when it comes back, it’s still coming through a crappy microphone and digitized by a cheap ADC. I’ll play nice and assume Batman was really smart and came up with a nifty software hack to perform the real-time compression of ultrasound. How does he know which direction the echo came from?

Sonar in animals depend quite heavily on being able to tell exactly where a sound came from. For bats and some birds, it’s the pair of ears on their head. For whales, they use their lower jaw and ears. These mechanisms allow them to precisely figure out direction as well as distance. A cell phone has a very limited ability to detect direction, not enough to give the detailed pictures in the movie. The microphones on cell phones are designed to be very responsive in a narrow band in front of it and almost deaf to anything outside of that band. So at best you’ve got a spotlight, but all you get back are a bunch of echoes that tell you nothing of the shape or direction. The microphone still can’t tell what angle the echo came in at.

The one part about that plot device that came close to reality was monitoring all that cell phone traffic for someone’s voice: there are rumors that the NSA’s ECHELON program can pick out voices of “parties of interest” from thousands of calls. Of course, I’m sure that’s just tin-foil hat thinking.

However, other comments say that it still might be possible…

Other cool Batman gear:

A Sonar Company:

I will look into this further! Have a good one! Yours,

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