Webster, J.C., Schubert, E.D. (1954). Pitch shifts accompanying certain auditory threshold shifts. J. Acoust. Soc. Am. 26, 754-758

A method was developed for getting a continuous and running record of pitch matches between the two ears ...

Ten music students made these pitch matches (90 matches per octave) from 150 to 9600 cps. In the ear in which the standard tone was heard various types of hearing loss were simulated by masking noises. The pitch tended to shift away from a region of hearing loss to a region of no, or less hearing loss. Downward shifts were observed but were never as marked as the upward shifts.