8K is adequate believe it or not. I tested people for five years. 16K is only one octave up. Getting equipment to properly measure higher would be really tough. If you have an HF problem 2,3,4,6 and 8K will show it as will word testing that emphasize consonants that require good HF hearing like words with s,th,ch and so on. I also prefer in the ear tips over over the ear headphones for accuracy and relief from ambient room noise for the most accurate results.
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