Modified on
Solving the
Mystery of the Sonar of Dolphins

by Douglas Moreman

Some Related Links

Animation, 07May2013

In about 2001, I stumbled onto an idea of how dolphins might "see" by means of echoes from the clicks of their sonar.

The beginnings of that possible solution were presented in U. S. Patent "Echo scope", granted in 2008. The approach was based upon a concept of massively parallel processing via special neurons, I call them "torons," in the brains of dolphins.
In Fall 2017, I submitted newer ideas, more suitable to serial computers, in three applications to the U. S. Patent Office.

The methods of solution introduced here begin with this idea:
rather than their ears, torons compare times-of-arrival ("toas") of echoes that arrive at echotrigger sensors in their jaw (perhaps just in the chin).

Simulations suggest that one can build a device that computes upon echoes of clicks of a dolphin and that displays an image of what that dolphin is acoustically "seeing." Perhaps some day, we will see such imaging on display in dolphin aquaria.

A new invention, spun-off from more general developments, is that of a simply-built improvement on existing fish-finders:
Streaming Fish-Finder in 3D.

This note of June 2014 marks the beginning of three years of work:

I have untangled this mystery: it had dawned on me that in my latest simulations, redone to demonstrate Feature-Based Passive (FBP) methods, my arrays were of much smaller diameter than the previous ones - and I had very little clue what I had done to make this possible. I have solved this mystery and can now show how to make a sonar-array for imaging in the manner, if not the sophistication, of dolphins. The simulated array is about the size of the chin of a bottlenose dolphin.

Summer 2015. I am writing the strategic patent (application) that I call "Toascope," reflecting the use of times-of-arrival ("toas") of feature-of-waves at sensors in an array.

(That patent was submitted under the title Toascope: sonar and radar imaging inspired by dolphins, in July 2017 and, in the three years from 2014, I coded another simulator, invented the 3D streaming fish-finder, and submitted two other provisional applications for patent.)

Mathematics of the Sonar of Dolphins

This new computational method for sonar and radar, Feature-Based Passive, FBP, enables computation of an image from a single "click" like that of a dolphin. The waves used for imaging are not limited to sound. Ideas for applications include
* the world's best fish-finder and and analogous radar applications that can help locate sources of enemy fire.
* high speed, inexpensive imaging for medical triage.

The new approach to computing images from waves has been inspired by the Echotrigger/Toron Theory of the imaging sonar of dolphins. But, since the mathematics applies to waves other than those of sound, a new name, wavar, has been adopted to refer to the general principles.

Wavar, here, is being developed using "experiment-machines" -- simulations software for rapidly crafting and running experiments that probe for information in waves.

The approach, here, is "geometric" in that its calculations use geometry and not sophisticated methods of analysis such as Fourier analysis.

The new (I think) and simple signal-processing methods herein are "feature-based" and "passive" in that they use times-of-arrival of known features of particular waves and can use, but do not require, knowledge of time and place of emisssion of those waves.

It seems that in most species of toothed whale, for which sonar-clicks have been recorded and graphed, the clicks all have one prominent instance of a feature called a fang.

A fang is a change in loudness that goes from a low to a high and back to a low in, typically, about 1/100,000 second and is much greater than all the other low-to-high transitions in the click. Given a known feature such as the "fang," but not knowing the time or the place of the emission of a click, FBP can, nonetheless, make a picture from echoes arriving at an array of sensors.

The scope of potential applications of geometric sonar include all areas of sonar, radar, exploration-seismology, and medical imaging. And more.

Douglas Moreman

Sonar of Dolphins

Applications of This New Technology
The Echotrigger/Toron Theory, How Neurons Can Image with Sound
Why "Echolocation" Cannot Explain the Sonic Vision of Dolphins
Abstract: Hypothetical Neurons
Sample Program for Experimenting
Odds and Ends
"Sonic Imaging," presented at a meeting at Tulane University in 2005. The animation represents the possible functioning of a first version of "the world's best fish-finder" -- it operated in "active mode."

An animation of active sonar that went with the introduction at Tulane (2005),
Improved Feature-Based Passive images, simply obtained (2005).
A first animation of FBP based on runs of a simulator, April 2013.
Animation, May 2013.

Thanks in Memorium, two tutors in the use of sounds for detecting and imaging:
John Gitt, Chief Scientist of Westinghouse Oceanic Division
Donald Haefner, retired Chief Geophysicist of Shell Oil

This web site was begun in April, 2013.
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