Normal hearing tests and audiograms go up to 8khz. Human hearing can extend to around 20 khz though. I also imagine that some people have tinnitus above 8 khz and may be helped by a hearing aid that goes beyond that. However, many places have audiometers that only go up to 8 khz. You can though call around different places where you live such as Ear, Nose, and Throat doctors or other facilities where they do a full hearing evaluation and ask if they do hearing tests above 8 khz. I was able to find atleast 3 places in my area. One went up to 12.5 khz, another up to 14 khz, and one up to 18 khz! Although, my audiologists only sell hearing aids that go up to 12 khz. These advanced hearing tests may be beneficial to you all in finding extended hearing loss. I wish you the best.