When the imagery of childhood fairy tales meets the more clinically analytical mind of an adult, there may at some point come the question, ‘how do mermaids hear’? Luckily a department of biology in Denmark has sought to furnish such an enquiring mind with an answer. As explained in the paper, the pinna has been adapted to diffraction of frequencies above the waterline and, therefore, is ill-equipped to deal with the changes which occur below it, so what about the other aspects of the auditory system? Using seven subjects, the researchers tested eight frequencies for changes from the subjects ‘in-air’ thresholds to those received underwater. In three subjects they also tested their ability to assess the direction of sound underwater. Though there are some minor questions regarding test procedure and a small study size, the larger issues, such as stringent methodology for reducing the background noise for the underwater test, are well founded. The findings show humans’ limited ability to localise low-frequency sound underwater, their reduced hearing ability across all frequencies tested, and suggest that bone conduction is unlikely to be the primary method of hearing below 1KHz. The enquiring mind should, therefore, conclude they might be better to wait until the mermaid surfaces before engaging in conversation.