Cuddy, L.L. (1968). Practice effects in the absolute judgment of pitch. J. Acoust.  Soc.  Am. 43, 1069-1076

Three experiments are reported in which the relation between practice and the absolute judgment of pitch was examined. Experiment 1 showed that  students with training in music could judge pitch more accurately than students with little or no music training. In Expts. 2 and 3, listeners were given systematic training that stressed the identification of a single reference standard - A_4, 440 Hz. Following such training, listeners showed improved recognition of A_4 (Expt.2) and improved recognition of a series of 10 tones (Expt. 3). Training on the reference standard A_4 was more effective in improving the performance of music students than was training in which the listener was required to name each tone and was then told the correct response (regular feedback).