... variety of environments and conditions, accurate air, bone conduction threshold testing, the automatic fast Speed testing capabilities ... free field frequency 125-8000Hz, loudness -10 - 120dBHL; Bone conduction 250-8000Hz, loudness -10 - 70dBHL. Error less than ... ± 1%. Output: air conduction headphones, bone conduction headphones, insert earphones, insert masking. Call: built-in ...