Real time measurement of the first formant frequency

Measurement of the first formant frequency has been a compromise between inaccurate real time techniques and accurate but relatively slow digital computing techniques. This paper presents a method that increases the accuracy of real time measurements in which the analog signal was low pass filtered and the period of the formant frequency ring identified by marking pulses. These pulses triggered a ramp which produced a voltage that was proportional to the period of the first formant. An analog divider inverted the numerical value of the period voltage, producing a voltage that was proportional to the frequency of the first formant.