I summarise a number of studies, some going back to the 1960s, which suggest that there are interesting individual differences in pitch perception. In particular, individuals appear to respond differently to a stimulus consisting of a few pure tone partials that could be integral multiples of a missing fundamental frequency (e.g. a stimulus consisting of partials at 400, 500 and 600 Hz, which has a missing fundamental of 100 Hz): some listeners appear to treat the missing fundamental as the pitch (i.e. 100 Hz in the example) and others appear to hear pitch at the frequency of the lowest partial actually present in the stimulus (i.e. 400 Hz in the example). I will demonstrate some of the experimental tasks that have been used to study this phenomenon, and describe our own recent pilot studies, which replicate the general finding, but which also suggest that individuals may switch from one pitch perception strategy to the other fairly abruptly as the overall frequency of the stimulus increases. I will also discuss the implications of this general phenomenon for speech perception, and consider the possibility that differences in pitch perception might be part of the genetically-influenced "cognitive bias" postulated by Dediu and Ladd (2007) as one of the factors explaining the distribution of tone languages in the world.