I’ve long felt the need for a device that can see sound, ie. to locate multiple sound sources in 3-D and display the result as an image.

The best I’d come up with was a disco ball studded with parabolic reflectors and a microphone at the focus. Each reflector points in a slightly different direction so by mapping sound intensity vs direction gives a 2-D image of the sound source, and from the frequency distribution at each microphone we would get coloured time-varying images.

But perhaps whales, dolphins and porpoises already have a better method of seeing sound. Many of these have an organ known as a melon sitting on the forehead outside of the skull. “The melon is a mass of adipose tissue found in the forehead of all toothed whales. It focuses and modulates the animal’s vocalizations and acts as a sound lens. It is thus a key organ involved in communication and echolocation.”

Could a melon act as an earball, analogous to the eyeball, a sound-focusing lens that generates a 2-D coloured time-varying image of external sound (and ultrasound) sources?

Could it also work above water?

The simplest scientific test of this hypothesis would be to use an ultrasound device (similar to a medical ultrasound) and place differently shaped plastic bags filled with oil between source and microphone to see if we could get a) amplification, b) localisation. Try both above water and underwater.

interesting idea

Check if this makes sense.

The speed of sound in seawater is higher than in just about any other liquid at room temperature. This includes a range of oils. Castor oil comes close, though.

That would mean that a lens of oil acts as a divergent lens. Or is it convergent. Check Snell’s law again. The angle of refraction is less than the angle of incidence if the velocity of refraction is less than the velocity of incidence. So it does make sense.

Underwater (but not in air) a ball filled with oil will focus sound somewhat. Most room temperature liquids would also do. I wonder if ship military sonar uses that.

And in air, a balloon filled with a heavy gas (such as CO2, SO2, cyclohexane, chloroform, sulfur hexafluoride, laughing gas) will focus sound somewhat. Why does this remind me of a parade in Gotham city led by the Joker?

mollwollfumble said:

I’ve long felt the need for a device that can see sound, ie. to locate multiple sound sources in 3-D and display the result as an image.

The best I’d come up with was a disco ball studded with parabolic reflectors and a microphone at the focus. Each reflector points in a slightly different direction so by mapping sound intensity vs direction gives a 2-D image of the sound source, and from the frequency distribution at each microphone we would get coloured time-varying images.

But perhaps whales, dolphins and porpoises already have a better method of seeing sound. Many of these have an organ known as a melon sitting on the forehead outside of the skull. “The melon is a mass of adipose tissue found in the forehead of all toothed whales. It focuses and modulates the animal’s vocalizations and acts as a sound lens. It is thus a key organ involved in communication and echolocation.”

Could a melon act as an earball, analogous to the eyeball, a sound-focusing lens that generates a 2-D coloured time-varying image of external sound (and ultrasound) sources?

Could it also work above water?

The simplest scientific test of this hypothesis would be to use an ultrasound device (similar to a medical ultrasound) and place differently shaped plastic bags filled with oil between source and microphone to see if we could get a) amplification, b) localisation. Try both above water and underwater.

Check if this makes sense.

The speed of sound in seawater is higher than in just about any other liquid at room temperature. This includes a range of oils. Castor oil comes close, though.

… Check Snell’s law … the speed of sound in the lens has to be less than in the surrounding medium.

Underwater (but not in air) a ball filled with oil will focus sound somewhat. Most room temperature liquids would also do. I wonder if ship military sonar uses that.

And in air, a balloon filled with a heavy gas (such as CO2, SO2, cyclohexane, chloroform, sulfur hexafluoride, laughing gas) will focus sound somewhat. Why does this remind me of a parade in Gotham city led by the Joker?

On the disco ball idea, I was wondering how to cut parabolic reflectors in a ball. I think I’ve got it. Two step process to cut the parabolas. Start by making a tee shape of strong non-conducting material supporting a hot wire. Push into styrofoam and twist 180 degrees to remove a cone-shaped plug. Then next step use a hot parabola of sheet metal, rotate 180 degrees in the styrofoam to turn each cones into a parabola. Then line the parabolas with polyester resin to make them reflective. Then fit a microiphone at the focus of each.