This is an entirely fair comment. And it's typical of my experience as well, and I have a fair amount related to audio, though not as extensive as yours.
My mind works differently when it comes to language and the scope of possible meanings is something I always consider relevant.
What concerned me here was someone taking the colloquial definition of "ultrasound" literally, and making assumptions that are not valid in this context at all.
What the word actually conveys is both a matter of subtlety and frequency.
Turns out, having read the entire discussion, both are relevant in terms of threat assessment, and thinking about what is said more deeply can have a positive impact on a discussion of this nature.
All of which is why I chose to point out what "ultrasound" actually does mean linguistically.
Edit: In my experience, such uses can and do happen. I personally allow for it and use context to parse. Where there is ambiguity, I generally won't dismiss it out of hand.
Subsonic comes to mind here. As does the question why the word did not appear regarding these watermarks.
The answer may just be someone with far less domain expertise attempting to communicate.
No, it means "beyond." Like you point out, "across" means something else. The Latin for "above" is supra or super.
> ultra-, prefix:
> 1. Signifying ‘lying spatially beyond or on the other side of’
> 2a. With adjectives, signifying ‘going beyond, surpassing, or transcending the limits of’ (the specified concept).
> Etymology: Latin ultrā beyond, employed as a prefix in the post-classical ultrāmundānus ultramundane, and the later ultrāmarīnus ultramarine, and ultrāmontānus ultramontane.
Your quick trip through the etymology triggered an opsec thought:
It may be worth a suggestive talk to expand how people take words.
A pop culture reference would be Daniel Jackson from the series, "SG-1"
We may often be constrained in our ability to understand and assess by our own preconceptions relating to language.
"Ultrasonic" was interpreted very differently by any number of us having this watermarking discussion. How often do we make assumptions about the possible field of play based on language basics?
How often do those fail to be sufficiently inclusive?
I bet it happens more than we realize.
Seems like a good basis for a DEFCON talk. "Where is Daniel Jackson when your team needs him?"
I was focused on the etymology; the actual usage of "ultrasonic" is generally confined to high pitches, not low.
Worthwhile point still, though I wouldn't have responded had the commenter not stated a specific incorrect definition. How does this connect to OPSEC though?
The relation goes right to threat and solution scopes. In this case, someone working from an incomplete definition may well also work within an incomplete set of greater assumptions.
There is what it could mean, what we take it to mean, and what it does mean.
Where those overlap or not could have a significant impact on behavior.
Wikipedia's definition has it explicitly higher. https://en.wikipedia.org/wiki/Ultrasound
That page says:
> Ultrasound is defined by the American National Standards Institute as "sound at frequencies greater than 20 kHz".
'Ultraviolet' means only higher-than-violet.
We have another word 'infrasound' for lower-than-audible frequencies.
I'm a native English speaker technically interested in sound for 40 years and I have never heard the 'subtlety' usage.