Grayscale plot and the contours detected for a channel specific compression of hearing aid channel 5 (HAC 5) of the research hearing aid (RHA). Panel (a)–(d) show the results for different compression ratios (CRs), and panel (e) depicts all contours detected within one plot. In panel (f), the number of pixels enclosed by the contours is plotted against the amount of gain reduction due to different CRs.