1. An active noise reduction (ANR) circuit comprising: a digital feed-forward ANR pathway coupled to a feed-forward microphone, to detect environmental sounds in an environment external to a casing, and coupled to a first acoustic driver to output sounds within the casing; and a user input; wherein the digital feed-forward ANR pathway applies a filter using a first set of coefficients to convert signals from the feed-forward microphone to feed-forward anti-noise sounds to reduce environmental sounds within the casing, and in response to activation of the user input, the digital feed-forward ANR pathway applies the filter using a second set of coefficients, the second set of coefficients reducing the degree of feed-forward ANR to enable human speech sounds in the environment external to the casing to be conveyed from the feed-forward microphone to the acoustic driver with less reduction than provided by the first set of coefficients.