It might be subtly irritating to be around the US machine when it is in operation (via bone conduction and other ways we sense ultra high frequencies), but can your hearing be damaged by frequencies that are so far above the range of audibility? The frequencies are an octave or more above 20kHz, are they not? It's an interesting question.
What I was trying to say to the issue of damaging LPs is that there are dozens of machines on the market. They vary quite a bit as to the frequency at which they operate and to the energy imparted into the bath. No manufacturer wants to be associated with a product that does damage, but human error can be a b**ch, so caution is merited, IMO. A third factor that theoretically could contribute to a damaging effect and which is not under the control of the manufacturer is length of time in the bath.
What I was trying to say to the issue of damaging LPs is that there are dozens of machines on the market. They vary quite a bit as to the frequency at which they operate and to the energy imparted into the bath. No manufacturer wants to be associated with a product that does damage, but human error can be a b**ch, so caution is merited, IMO. A third factor that theoretically could contribute to a damaging effect and which is not under the control of the manufacturer is length of time in the bath.