So the dolphins, singly and in pods are masters of phase control.
What can a dolphin do with these sounds?
Dolphins use high intensity sound pulses to stun fish and other prey. If their 1KW of acoustic power were focused to a small point, the water would turn to steam, causing cavitation. This level of acoustic power focused on a fish could easily stun or kill it. Dolphin sounds are loud enough to allow communication over a range of at least 36 miles.
When dolphins use their sonar, they direct sounds toward a target and receive the returning echoes with their ears. The dolphin may perceive an echo “image” showing density differences in the target, be it a fish or a human body. For example, gas bubbles in the stomach reflect sound strongly, while soft tissues with densities near water are largely “transparent” to the sounds. Bones, being denser than water, also reflect strongly. Therefore, the dolphin may have a sort of “acoustic X-ray image” of us in the water, much like the images formed using medical ultrasound.
At frequencies of 280 kHz to 1 MHz, dolphins are able to sense quite small features, perhaps with resolutions under a millimeter. We know that they can detect and retrieve a 2mm diameter “BB” shot dropped in the water at a range of 70 feet. Dolphins could also focus sounds into spots under a millimeter. With 4-5 separate sound sources, use of other techniques like acoustic interferometry are possible.
Dolphins produce what are called semi-coherent acoustic waves where a sound’s wavefronts are “in step” or “in phase” and therefore are, roughly, like an acoustic “laser”. As we saw they can steer their sounds using techniques akin to phased array sonars and maintain phase coupling among two or more dolphins.
Dolphins could use what is called “time reversed acoustics”. In this technique, incoming sounds are recorded at several points and then played out in reverse to send an amplified sound directly back to its source. Such techniques have been used to break up kidney stones using what is called a self-focusing lithotryptor.27
From the dolphin anatomy and sound capability, I conclude they are capable of many such feats. Consider the complexity of the 3-D sound fields the dolphins could create in groups with each dolphin producing four sounds each, while maintaining tight phase locking among themselves. With four phonators plus a 130 kilohertz signal from the jaw, dolphins can focus their sounds into small areas at high powers. They can, in principal, break kidney stones, remove bone spurs, cause cavitation in small regions, etc.