Significance of implementing polarity detection circuits in audio preamplifiers

The reversal of the current directions in audio circuit elements causes polarity inversion of the acquired audio signal with respect to the reference input signal. The objective of the work presented in this paper is to implement a simple polarity detection circuit in audio preamplifiers which provides an indication of the signal polarity inversion. The present work also demonstrates the possibilities of polarity inversion in audio circuits of audio data acquisition devices. Inputs fed in the inverting/noninverting terminals of audio operational amplifiers (Op-Amps) cause polarity reversal of the amplitude values of the speech/audio signals. Even though, polarity inversion in audio circuits are perceptually indistinguishable, provides inaccurate values of speech parameters estimated by processing the speech. The work presented in this paper discusses, how polarity inversion is introduced at the circuit level and proposes a polarity detection circuit which provides an indication of polarity reversal after the pre amplification. The effectiveness of the proposed polarity inversion circuit is confirmed by 100 % polarity detection rate for the 100 randomly selected audio files of the CMU-Arctic database when simulated using Proteus 8.0. The paper is concluded by discussing the significance of VLSI implementation proposed polarity detection circuit in the most commonly used audio preamplifier systems.