The cochleogram is an important tool to visualize properties of the cochlea (e.g. hair cell loss, damaged hair cells) in dependence on their position in the cochlea. Using scanning electron microscopy (SEM) we performed an analysis of 171 guinea pig cochleas that were exposed previously to different noises. To evaluate the numbers of damaged, destroyed or lost hair cells, the cochlea was either divided into turns, each turn was divided into sectors and hair cells were counted per sector, or the cochlea was divided into sections of predetermined length and hair cells were counted per section. Using the sector-wise analysis, we found a mean basilar membrane length of 16.4±1.4 mm (mean±std. deviation) with turn lengths of 6.9, 4.2, 3.2, and 1.9 mm. The counting of hair cell loss in very short predeterminated sections resulted in a higher resolution of the cochleograms, but overestimated the loss of individual hair cells. The sector-wise analysis had advantages, since it allowed the comparison of different animals in one series, and the use of anatomical landmarks eased the analysis of even partly damaged cochleas, and it neglected the shrinking process. Therefore, we propagate the sector-wise analysis of the cochlea and a determination of sector lengths by using anatomical landmarks instead of counting the hair cells in predeterminated sections of fixed length.