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A mechanism for dc noise enhancement in the presence of a reverse dc field is presented. In particular, only in a medium where the grain switching fields increase monotonically with increasing grain size does the dc noise exhibit a spatially correlated amplification with respect to the dc erased state as has been recently observed in spin-stand measurements. The effect of this correlation was explored by generating media with random grains using a Monte Carlo grain growth model. In our study the media are assumed to be perfectly oriented and have a fixed nonmagnetic intergranular spacing. The magnetization is initially saturated in one direction and grains are reversed to simulate the application of a reverse dc field. The dc noise maximum occurs when the medium is in the zero net magnetization state. The noise power for the case of grain-size-correlated switching is approximately twice that (3dB) for the case of uncorrelated switching, in reasonable agreement with the experiment.