A personal active noise reduction device comprising: an acoustic driver; an ANR circuit coupled to the acoustic driver to operate the acoustic driver to acoustically output ANR anti-noise sounds to provide ANR at a location adjacent an ear of a user of the personal ANR device across a range of frequencies having a lower limit and an upper limit; and at least one digital filter (250;350) of the ANR circuit, wherein: the at least one digital filter is configurable with a plurality of coefficients to implement an ANR transform to derive the ANR anti-noise sounds from ANR reference noise sounds; the ANR circuit is configured to repeatedly reconfigure the at least one digital filter with different pluralities of coefficient values at a first recurring interval to reduce the provision of ANR at one of the lower limit or the upper limit without reducing a magnitude at which the ANR is provided across the entire range of frequencies in response to an event adversely affecting the provision of ANR at the one of the lower limit and the upper limit; and the ANR circuit is configured to repeatedly reconfigure the at least one digital filter with different pluralities of coefficient values at a second recurring interval to reverse the reduction in the provision of ANR at the one of the lower limit and the upper limit in response to the event adversely affecting the provision of ANR at the one of the lower limit and the upper limit having ceased, wherein the provision of the ANR at the one of the lower limit and the upper limit is reduced by changing a slope at the one of the lower limit and the upper limit to make the slope more shallow in steps with each of the first recurring intervals, wherein a transition bandwidth occupied by the slope widens as a cutoff frequency associated with the slope is moved inward into the range of frequencies in steps with each of the first recurring intervals. an acoustic driver; an ANR circuit coupled to the acoustic driver to operate the acoustic driver to acoustically output ANR anti-noise sounds to provide ANR at a location adjacent an ear of a user of the personal ANR device across a range of frequencies having a lower limit and an upper limit; and at least one digital filter (250;350) of the ANR circuit, wherein: the at least one digital filter is configurable with a plurality of coefficients to implement an ANR transform to derive the ANR anti-noise sounds from ANR reference noise sounds; the ANR circuit is configured to repeatedly reconfigure the at least one digital filter with different pluralities of coefficient values at a first recurring interval to reduce the provision of ANR at one of the lower limit or the upper limit without reducing a magnitude at which the ANR is provided across the entire range of frequencies in response to an event adversely affecting the provision of ANR at the one of the lower limit and the upper limit; and the ANR circuit is configured to repeatedly reconfigure the at least one digital filter with different pluralities of coefficient values at a second recurring interval to reverse the reduction in the provision of ANR at the one of the lower limit and the upper limit in response to the event adversely affecting the provision of ANR at the one of the lower limit and the upper limit having ceased, the at least one digital filter is configurable with a plurality of coefficients to implement an ANR transform to derive the ANR anti-noise sounds from ANR reference noise sounds; the ANR circuit is configured to repeatedly reconfigure the at least one digital filter with different pluralities of coefficient values at a first recurring interval to reduce the provision of ANR at one of the lower limit or the upper limit without reducing a magnitude at which the ANR is provided across the entire range of frequencies in response to an event adversely affecting the provision of ANR at the one of the lower limit and the upper limit; and the ANR circuit is configured to repeatedly reconfigure the at least one digital filter with different pluralities of coefficient values at a second recurring interval to reverse the reduction in the provision of ANR at the one of the lower limit and the upper limit in response to the event adversely affecting the provision of ANR at the one of the lower limit and the upper limit having ceased, wherein the provision of the ANR at the one of the lower limit and the upper limit is reduced by changing a slope at the one of the lower limit and the upper limit to make the slope more shallow in steps with each of the first recurring intervals, wherein a transition bandwidth occupied by the slope widens as a cutoff frequency associated with the slope is moved inward into the range of frequencies in steps with each of the first recurring intervals.