VOLUME 9OING over the literature on absolute pitch • one notices that comparatively few cases have been studied, but that a great variety of claims are made as to the phenomena and the nature of absolute pitch. This leads one to assume that various grades and even different types of aksolute pitch may occur.For the purpose of a classification of absolute pitch, 103 cases were studied and compared with observations made on 7 persons without absolute pitch. Ninety possessors of absolute pitch were examined on the piano, the tone variator, and tuning forks. Most of them were tried on other musical instruments, singing and whistling, and also on nonmusical sounds (of bells, glasses, automobile horns). In the course of the experiments the results obtained by tuning forks, piano, and violin proved to be identical, because of the relatively large intensity of the fundamental and the second harmonic in the latter instruments. These three instruments produce the most easily recognizable tones to possessors of absolute pitch. For practical experimentation, the piano proved to be the most useful of these instruments.Sounds from musical instruments with strong higher harmonics--also singing and whistling--are more difficult to recognize by some persons with absolute pitch. The tone variator was the most useful apparatus in this class for its continuous frequency scale. Bells, glasses, and horns were not recognizable to most persons due to very disturbing unharmonic overtones. They were used only for establishing the limits of extraordinary absolute pitch faculties. Thirteen possessors of absolute pitch, which could not be approached directly, were studied by use of a questionnaire. These observations have led to a clear distinction of different PITCH ESTIMATION BASED UPON TONE H EIG-HT [• // Itlllllllll-IIIIIIIIIIIllllllllllfllllllll

The author, who possesses absolute pitch since the time of his earliest musical experiences at the age of five years, has spent much time in studying this musical phenomenon. Amused by the fact that the most extensive work on “absolute pitch” was conducted by psychologists who did not possess this faculty and that it was done on large groups of students, none of whom possessed this faculty either [For exception see O. Abraham, Sammelbde d. Internat. Musikges 3, 1 (1901) and G. Révész, Zur Grundlegung der Tonpsychologie (Leipzig)], he was convinced that a study by a possessor of absolute pitch on himself and on a large number of other possessors of absolute pitch might lead to different and better results. An original study [A. Bachem, J. Acoust. Soc. Am. 9, 146 (1937)] was conducted on 96 possessors of absolute pitch and 7 more or less musical persons without this faculty for comparison. The work was extended in the course of time to specific related problems which presented themselves through several discoveries.

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Error measures of pitch discrimination were obtained as a function of the time lapse between standard and comparison tones. The time interval ranged from one second to one week, establishing a “curve of forgetting.” Half of the subjects possessed absolute pitch. Results indicate that for short time intervals there is no observable difference in pitch discrimination between the two groups of subjects. With longer intervals there is a decided discrepancy, so long as the tone is within the musical range. This discrepancy in time-error curves is attributed to the shift from relative pitch comparison to chroma identification by those subjects possessing absolute pitch. The lack of discrepancy at the upper border of the musical frequency scale is attributed to chroma fixation. The curves of forgetting are more sigmoidal than straight logarithmic, particularly in the case of absolute pitch.