The hammer-headed bat is the largest bat in mainland Africa. Males have wingspans up to , and all individuals have forearm lengths exceeding . It has pronounced sexual dimorphism, more so than any other bat species in the world, with males up to twice as heavy as females. The average weight of males is , compared to for females. Other differences between the sexes relate to their social system, in which males produce loud, honking vocalizations. Therefore, males have greatly enlarged larynges, about three times the size of females', extending through most of the thoracic cavity, and measuring half the length of the spine. The larynx is so large, it displaces other organs, including the heart, lungs, and gastrointestinal tract. Males also have resonating chambers to increase the volume of sound production. These chambers are pharyngeal air sacs connected to a large sinus in the humped snout. These numerous adaptations caused scientists Herbert Lang and James Chapin to remark, "In no other mammal is everything so entirely subordinated to the organs of voice".