Firstly, the 'audio spotlight':

The audio spotlight, invented by MIT graduate Joseph Pompeii in 2002

This uses a narrowly-focussed ultrasonic carrier beam:

Of course, the ultrasound, which contains frequencies far outside our range of hearing, is completely inaudible. But as the ultrasonic beam travels through the air, the inherent properties of the air causes the ultrasound to distort (change shape) in a predictable way. This distortion gives rise to frequency components in the audible bandwidth, which can be accurately predicted, and therefore precisely controlled. By generating the correct ultrasonic signal, we can create, within the air itself, essentially any sound desired.

I attended a presentation on this given by the head of the MIT media lab in 2002. One of the facts not commonly mentioned is that the ultrasound carrier beam needs to be powered at about 150 decibels, which I would think could be physiologically damaging ..?

"How Stuff Works' also still has an article from 2000, chronicling the 'work in progress' (with some extra links)

And now, to 'microwave hearing' ..

From WRAIR US Army Medical Research Establishment (PDF file):

The most frequently cited sequence of events used to explain auditory sensations resulting from
microwave pulses, or “microwave hearing”, starts with transduction of microwave energy to sound in the head.
In this explanation, the sound is then transmitted through cranial bones, i.e., by bone conduction, to stimulate
hair cells in the inner ear. Recently reported experiments with animals and humans indicate that sound
conduction through bone itself is not necessary in bone-conduction hearing. Instead, sound generated inside the
cranium is most efficiently transmitted through holes in the cranium that form channels to the inner ear:
vestibular aqueduct, cochlear aqueduct, and/or perivascular and perineural spaces. The short latency of cochlear
microphonics reported for microwave hearing and the oscillation of the microphonics at the calculated brain
resonant frequency are consistent with transmission through the channels. Thus, the channels are the most likely
pathway for transmission of sound to the inner ear in microwave hearing. Consideration of this transmission
pathway may be useful in reconciling results from various microwave hearing experiments.

And, another PDF from <a href=http://grouper.ieee.org/groups/scc28/sc4/Auditory%20effects.pdf">Motorola Florida Research Labs

And, from Cornell University, School of Electrical Engineering and Cornell Aeronautical Laboratory:

The "hearing" of electromagnetic waves is an established fact. It appears that this takes place by direct stimulation of the nervous system, perhaps in the brain, thus bypassing the ear and much of the associated hearing system. It is a possible, perhaps the most probable, explanation of the reports of hearing meteors and auroras. It is also a possible tool in the investigation and treatment of problems in hearing.

Conclusion: the acoustic spotlight and microwave hearing are both HARD, ESTABLISHED SCIENCE and NOT paranormal psychobabble. HZers should be focussing their critical faculties on the paranoid-conspiracy elements of the 'Mind Control' set, without dismissing the basic science. And even there, keep in mind that this science, and the existing technology, does make it possible IN PRINCIPLE IF NOT IN PRACTICE, to carry out forms of auto-suggestion and mind-control.

NOTE: I AM NOT SAYING THIS FORM OF MIND CONTROL IS BEING PRACTICED. I AM SAYING ONLY THAT THE BASIC SCIENCE IS VALID, AND THE TECHNOLOGY NOW EXISTS FOR POSSIBLE AUTOSUGGESTION. I AM NOT SAYING THAT IT IS ACTUALLY HAPPENING, HOWEVER. I AM SAYING HOWEVER, THAT 'MIND CONROL' CLAIMS HAVE TO BE DEALT SERIOUSLY WITH ON A POLITICAL AND SOCIAL CRITICAL BASIS, AND NOT ON A SCIENTIFIC BASIS, SINCE THE BASIC SCIENCE IS VALID. THE HZ KNEE-JERK REACTIONS WERE WRONG, WRONG, WRONG.

Extra side-rant:
'
I should have known better than to follow the lead of you guys on this issue, since in my 10 years experience, the overwhelming majority of scientists and engineers are totally ignorant and uninterested in acoustics and hearing (called 'psychoacoustics'). For instance, I have a longstanding offer for a living scholarship to start a Phd at Sydney University Physics - which I have declined to take up since 2002. Why, you may ask with bated breath? .. because not a single solitary researcher has anything to do with acoustics of any description: it's exclusively optics, optics, optics - and more freaking optics. And the same pattern is duplicated at the other major Australian universities: ANU, UNSW, Monash, Melbourne, and Adelaide. Tone-deaf, and proud of it.

(end of extra side-rant)