Dont think this study has been linked yet but https://asa.scitation.org/doi/10.1121/1.5063819 found that some people did suffer adverse effects from frequencies that they can no longer actually hear. The study in questions used frequencies ranging from 13.5khzto 20khz on people who could not longer actually hear them based on their hearing tests. Very interesting results, basically people exposed to the high frequencies experienced feelings of irritation and had difficultly concentrating on a task. Not "true" ultrasonics as that is within the human hearing range but those people had lost that hearing. The study came to being after people found that the goddamn mosquito sonic weapon used in Europe was causing them irritation I believe. Those things should be banned, I cant believe people are ok with destroying kids hearing like that. I have seen reports of it as much as 108db in volume! A teenager will just leave before there is any serious damage but what about a parent taking a baby around, baby will be having their ears murdered and parents might just feel mild irritation not realizing what is happening. Infuriates me as a parent. Study also brings up a very interesting point which is that part of the reason there arent more studies of ultrasonic sounds is that in many cases to truly find out if there were any adverse effects you would need to expose the subjects to very high volumes 100bs/spl or more which is unethical for any researcher who actually believes it will do harm to do. I think people handwave away the effects of ultra and infasonic partially because they arent accounting for what might happen if they are exposed to very high volumes rather the relatively low noise from CRTs and such.