Auditory ossicles and the evolution of the primate ear
a biomechanical approach
pp. 67-86
in: Jan Wind, Brunetto Chiarelli, Bernard Bichakjian, Alberto Nocentini, Abraham Jonker (eds), Language origin, Berlin, Springer, 1992Abstract
From a morphometric viewpoint, the variability of the ear ossicles of humans and of the other primates appears to be suitable for the study of taxonomic and phylogenetic relationships. Also, this variability could be useful for detecting interspecific differences in the perception of sounds from the environment and from conspecifics. The sound energy transmitted by the ossicular chain is maintained by the action of various levers, while the pressure of the sound waves is amplified by the ratio between the area of the ear drum and that of the oval window. As regards energy transmission, the relevant aspect is the change from the relatively wide, low energy movements of the hammer to the smaller, high energy movements of the stirrup. This pattern of energy transmission and pressure amplification was studied by a morphometric model applied to samples of human and great ape skulls. The results are discussed in relation to acoustic mapping of the environment and decoding of vocal signals.