The effects of mouth movements, swallowing, and spitting on retronasal odor perception.

Although attempts have been made to compare sensations produced by orthonasal and retronasal olfactory stimulation, previous studies have failed to address the dynamic nature of retronasal perception. In this study we demonstrate the importance of oral movements in influencing the perceived retronasal olfactory intensity. For orally-presented solutions of artificial orange and rum extract solutions, average magnitude estimates of eight subjects were significantly increased by various mouth movements (including spitting and swallowing) over a no mouth movement condition. These findings demonstrate that retronasal odor perception is a highly dynamic process, and suggest the hypothesis that mouth movements play a role in retronasal odor perception analogous to that played by sniffing in orthonasal perception. In addition, these data suggest that some disorders of deglutition may have associated chemosensory consequences.

Interindividual differences in acuity for odor and aroma.

To determine the olfactory acuity of 27 subjects a sensory test was presented which was divided into 4 subtests, 2 for nasal and 2 for oral stimulation. Each subtest contained 28 (4 substances X 7 concentrations) olfactory detection tasks (items). The substances used were lemon and rum aroma as well as ethyl butyrate and amyl acetate, the solvents tap water and sugared tap water. Analysis showed that the test provided a clear differentiation between subjects of low, medium, and high olfactory acuity. The intercorrelations among the test substances and the split-half reliabilities of the subtests proved relatively high, whereas only moderate to low intercorrelations among the subtests were found. This was considered an effect of intraindividual variations of olfactory sensitivity. Finally, some conclusions for the construction of acuity tests for odor and aroma are presented.