Apparatus for Recording Frequency, Duration, and Sequence of Verbal Responses
Nathan W. Gottfried, James H. Davis · Psychological Reports · 1964
An apparatus was designed to record the duration and frequency of vocal responses. Utilizing a circuit employing an output transformer, diode rectifier, and an electrolytic capacitor, the output of an audio amplifier activates a sensitive relay. The switching circuit of the relay connected to an event recorder produces a permanent record of S's vocal responses.