text: A widely publicized study suggested that humans can detect more than one trillion different odors. This finding has been disputed. Critics argued that the methodology used for the estimation was fundamentally flawed, showing that applying the same argument for better-understood sensory modalities, such as vision or audition, leads to wrong conclusions. Other researchers have also showed that the result is extremely sensitive to the precise details of the calculation, with small variations changing the result over dozens of orders of magnitude, possibly going as low as a few thousand. The authors of the original study have argued that their estimate holds as long as it is assumed that odor space is sufficiently high-dimensional.