Dual microphone noise cancellation using LF351 Op Amp
Dual microphone noise cancellation (also known as Dual Mic ANC) is a technique used to improve the quality of audio captured by microphones in noisy environments. This circuit dual microphone noise cancelling using LF351 Op Amp uses two mics back to back, each amplified, one inverted, and then summed with each other. The predominant voice on the front one is not present on the rear mic so remains after the common noise on both is cancelled. Note that Microphones must face in opposite directions to obtain optimum noise cancelling. The mic biasing resistors R1 and R2 should be 4.7k to 6.8k.
Two microphones are used: One picks up the ambient noise along with the desired signal. The other (main mic) picks up the desired signal and the ambient noise. By inverting and summing the reference microphone’s signal with the main microphone’s signal, the common ambient noise component gets cancelled.
The LF351 is a low-noise, general-purpose Op Amp suitable for this application. It offers features like: Low input offset voltage (important for minimal signal distortion)High gain (to amplify the weak microphone signals) and Decent bandwidth (to handle a wide range of audio frequencies).