For a properly dithered recording, bit depth is exactly equivalent to noise floor. If low-volume details are lost in 16 bit recordings it is because their volum

For a properly dithered recording, bit depth is exactly equivalent to noise floor. If low-volume details are lost in 16 bit recordings it is because their volume falls near or below the noise floor imposed by the 16 bit recording. 16 bits is good enough because the noise floor is low enough to be imperceptible to a human, if the gain of the recording is such that the full dynamic range available is used