{HEAD ~ The input transducer} which is oriented facing the ear picks up {TAIL ~ residual noise} present in the ear canal which was not cancelled by the first input transducer to output transducer signal path due to non ideal frequency and amplitude characteristics 
{ HEAD ~ The input transducer } which is oriented facing the ear picks up { TAIL ~ residual noise } present in the ear canal which was not cancelled by the first input transducer to output transducer signal path due to non ideal frequency and amplitude characteristics
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH