PRESSURE TRANSFORMATION FROM A DIFFUSE SOUND FIELD TO THE EXTERNAL EAR AND TO THE BODY AND HEAD SURFACE

The sound-pressure-level transformations from a diffuse sound field to the head surface and the torso surface were measured. Transformations were measured on a manikin and on two subjects for frequencies between 0.2 and 10.0 kHz using 1/3-octave bandwidth random white noise. The pressure-level transformations to the center of the concha volume and to the ear canal entrance as well as to a microphone in an earlike coupler (using a manikin and six different-sized pinnas) were also measured. the maximum gain at the coupler microphone is approximately 15 dB at 2.7 kHz. This transformation to the head and torso surface depends strongly on the distance between the microphone and the heard or torso, and on the absorption of the head and torso, but not on the fine features of the head. Variations in pinna size have their greatest effect on the pressure levels in the outer ear above approximately 6 kHz, where higher-order acoustic modes are strongly excited in the pinna. © 1979, Acoustical Society of America. All rights reserved.