An allpass hear-through headset

In order to create a natural hear-through experience when wearing the headset, the acoustic attenuation of the headset itself must be cancelled. This is obtained by processing the ambient sound signals captured by external microphones. The sound perceived by the headset user will then be a mixture of the ambient sound that leaks through the headset and the processed ambient sound that is reproduced with the headset. We propose a new equalization method for designing such a hear-through system based on an allpass design principle. The proposed method takes the frequency-dependent isolation transfer function of the headset as the input and completes it with an engineered transfer function so that the outcome will be an allpass transfer function with a flat magnitude response.