Using the method of magnitude estimation, the experiments reported investigated the effect of the frequency of the standard upon the pitch functions for piano tones and randomly chosen pure tones. The pitch functions obtained are found to agree in an important respect with each other and with the function previously reported for pure tones chosen to correspond to notes on the musical scale. When the frequency of the standard was the lowest tone presented, the magnitude estimations yielded a function similar to the revised mel scale, and when the standard was a frequency nearer the middle of the series, the magnitude estimations yielded a steeper function closer to the original mel scale. Data are also presented showing that the numerical value of the standard can affect the magnitude estimation function. These results indicate that response biases relating to the frequency and numerical value of the standard may be expected to influence the pitch function determined by magnitude estimations. The nature and effect of these biases are discussed. It is concluded that care is required in viewing magnitude estimation judgments as reflecting a simple correspondence between frequency and the sensation of pitch.