In the past decade since PMR was commercialized there continues to be an inadequate understanding of the nature of noise in perpendicular media. Various models have been proposed to explain the typical behavior of a linear rise of integrated noise power vs. linear density, followed by a plateau (Figure 1). Some suggested explanations call for a tenuous balance between transition noise and ac noise or a delicate interplay of magnetics [1-6]. One of the earliest models [1] involved a hypothesis that the beginning of the plateau region corresponds to the transition spacing reaching the cluster diameter. The current paper agrees with that insight and shows corroborating data. We also agree with the earlier observation that the linear density corresponding to the beginning of the noise plateau also corresponds to the beginning of non-linear partial erasure (NLPE). We disagree with that earlier speculation that because NLPE typically coincides with percolation the noise plateau is due to percolation. We suggest that under most conditions the media's cluster sizes and size distributions are not fixed, but can be altered by the recording head. Essentially, a recording head with a sharp field gradient can cut the clusters in to smaller units. While it makes sense that percolation onset occurs at the same linear density = 1/(cluster diameter), percolation does not explain the noise plateau, but cluster cutting does.