In establishing norms for the investigation of certain psychoacoustic functions, it is sometimes desirable to obtain pure-tone measurements in 1 db. steps. Myers and Harris, as well as others,9 have demonstrated that, under carefully controlled experimental conditions, "the typical short-term fluctuation [i. e., of normal thresholds obtained with steady-state signals] is less than a decibel." The present study was designed to establish whether such findings are also demonstrable when pulsed tones are utilized for the threshold measurement.
A schematic block diagram of the apparatus is shown in the Figure. The various elements in the circuit were shielded from each other by the use of appropriate materials, and the study was conducted under acoustically quiet conditions.
—A General Radio beat-frequency oscillator (Type NO 1304-A) was used to generate the basic sine wave. The output of the oscillator was fed successively into an audiotimer (which turned the