I'm not positing an inflexible position, just suggesting that our assumption that the earlier usage of a word is naturally the correct one gets overturned by our concurrent, but in this case contradictory, belief that the most common use is correct.
Where words have a technical use, the specific meaning being clearly understood is important. In my former profession, there was an important difference in meaning between light, lantern, luminaire, lamp etc. Confusion could have been very dangerous. I suspect that, in technical environments, ultrasonic would be used for the audio meaning, and supersonic for velocity, almost exclusively.