A model of the occlusion effect with bone-conducted stimulation.
An acoustical model using simplified ear anatomy was designed to predict the ear-canal sound pressure occlusion effect in humans. These predictions were compared perceptually as well as with ear-canal sound pressure occlusion effect measurements using a foam earplug with shallow insertion, a foam earplug with deep insertion into the bony part of the ear canal, and a circumaural earmuff. There was good resemblance between model predictions and ear-canal sound pressure measurements. It was also found that all occlusion positions, even deep ear-canal occlusion, produced noticeable occlusion effects. With the bone-conduction transducer at the forehead, the perceived occlusion effect was close to that obtained from ear-canal sound pressure data in the 0.3 to 2 kHz frequency range; when the stimulation was at the mastoid the difference between the perceived and measured ear-canal sound pressure occlusion effect was around 10 dB at frequencies below 1 kHz. Further, the occlusion effect was obtained in two clinical settings: with supra-aural earphones (TDH39), and insert earphones (CIR22). Although both transducers produced occlusion effects, insert earphones produced a greater effect than surpa-aural earphones at the low frequencies.
Stenfelt
Stefan
S
Department of Neuroscience and Locomotion, Division of Technical Audiology, Linköping University Hospital, Sweden. stefan.stenfelt@inr.liu.se
Reinfeldt
Sabine
S
D000161:Acoustic Stimulation; D001309:Auditory Threshold / Q000502:physiology*; D001844:Bone Conduction / Q000502:physiology*; D017097:Electric Impedance; D006309:Hearing / Q000502:physiology; D006801:Humans; D008954:Models, Biological