It was a nice and well written story, though with known truths combined with hear say, non founded beliefs and assumptions based on personal observations.

consider the following:

In the 80's DAC's were in its infancy, analog filters technology with a steep drop-off was just beginning in development/application and had huge amounts of ringing, ripples etc.
They were barely able to make 14 bit DAC's that had like 11 bits ENOB.
Who knows what the guy used and why and where he got the 'tech' from (cutting edge or slapped together with stuff they had) ?

It is not inconceivable that they needed 800kHz (single bit ? ) DAC's and calculated 400kHz or they had low bit amounts of DAC's and had to use 800kHz (or 400kHz ?) sample frequencies to get the noise out of they or needed high sample frequencies so their filters didn't roll-off in the audible band.
Did he actually hear 400kHz or did he hear artefacts (within the audible band) others missed because they didn't 'look' for it ?
Who knows ?

That test data would have been saved if it was that important and articles would have been written about this.
It would have turned thinking (about audibility thresholds) around in those days.
Never seen any reports of this though.

The only loudspeakers that could go near 80kHz were plasma speakers in those days (no mass of diafragms) and piezos (but not at high enough SPL in free air)

It is a nice story ... but would bet my life either numbers are mixed up, remembered wrong or misunderstood.
The eardrum and bones in the ear don't vibrate at 400kHz either.
Only through bone conduction (at high SPL) one could make the hairs 'move' and the question is what these hairs would say.
400kHz or would they say '20kHz' and are just excited by higher frequencies ?

Too many issues to consider the 400kHz a 'reality'  even for a unique individual.



I do share the point about blind tests with larger groups.
even if just one person out of a hundred would actually be able to pick up a difference of something and others couldn't it would be waved away on account of statistics.

Of course there is always a chance someone passes a test by guessing correctly a number of times in a row.

What I would do is single out that person (of interest) and see if he guessed correctly or was able to hear this or that change.
I think every scientist would be very interested in those people, unless they had an agenda to disprove something.
IMO those truly interested in exploring human limits would experiment on that individual as if he was the holy grail.
There would have been papers about this strange individual with abnormal hearing.

Never seen any papers discussing 'rare' individuals that can perform such trickery.

Perhaps we should involve the mythbusters... they did test the brown note and shattering glasses with a voice.


Yes, some people are trained more than others or know what to listen out for.
Musicians don't always make better 'evaluators' certainly when it involves certain aspects they never listen out for.
They might pick out instruments sooner or more accurate than 'your average' person.
Also many sound engineers may not have the best ears/gears around.
I think there are many audiophiles that may hear (somewhat) 'better' than average people but reckon there are more audiophools than audiophiles around.
It probabably has to do with experience.
Can you tell them apart by the posts they make in forums aside from their age ?
I have noticed that the older we get the better the hearing appears to be (more experience with listening ?) but the crappier the ears themselves get.
Interesting aspect ....

There were no analo g recordings (tape nor vinyl) that could reach those mentioned frequencies.
If anything even the bias frequency of tape recorders would have been in the 200-400kHz range and any competent tape recorder designer that used a recording head with a single slit would have used a notch filter at the bias frequency for technical reasons.

Vinyl isn't capable of 400kHz. The rotational speed of the lathe platter would have to have been really low to scribe those frequencies into the master (much lower than half speed master).
Aside form that no needle would be able to pick it up (at normal speeds) and would have to have razor thin edges and the cantilever and coils would have to have an extremely low mass and be very rigid.

Fun discussion though, lets see where it leads to.
I am all ears ...