This investigation was designed to obtain the monaural loudness function for a 1000‐Hz tone. Ten trained observers with normal hearing were utilized. The method used was the numerical magnitude balance procedure. This investigation indicates that the results obtained by the numerical magnitude balance procedure are repeatable if the observers do not have previous knowledge of the decibel scale, and if they are properly trained. This is indicated by the good agreement of the results of this study with the findings of previous studies. The results of this study showed a loudness exponent of 0.54 based on data averaged by geometric means and 0.51 based on data averaged by medians.