VIRTUAL ACOUSTICS AND AUDIO ENGINEERING
Fluid Dynamics and Acoustics Group


 



 
HEAD SCATTERED ACOUSTIC FIELD DUE TO A MONOPOLE SOURCE
Frequency domain response with the DBEM

When the human head is simplified to the classical rigid sphere, analytical expressions exist for both the frequency response on the sphere surface and also the total sound field due to an excitation of a plane wave or a monopole source. However, it was demonstrated that the pinna can produce a much more complex structure of frequency response at high frequencies. An example of the sound field around KEMAR (without a torso) calculated with the DBEM is shown. In this case the mesh model of KEMAR included 10283 nodes and 20562 elements (of a full head), and the mesh of the field points around the head comprises of 200 × 200 points. The total (incident + scattered) sound pressure in an area of 0.5 m x 0.5 m is shown on a linear scale. The source is positioned in front of the head at a distance of 0.5 m from the centre of the head. The characteristics of the sound fields are very similar to the case of a sphere where at 200 Hz the head is almost transparent to the propagating waves. At 1 kHz the shadow zones appear at the rear, and an increase of pressure occurs in front of the head due to the superposition of the incident and reflected waves. As frequency increases (at 2 kHz and 5 kHz), the interference between these waves causes more complex patterns in front of the head and higher attenuation is noticed at the rear. In addition, the scattered sound field is slightly uneven on the left and right sides due probably to slight misalignment and due to the asymmetrical shape of KEMAR mesh model with DB60 and DB61 pinnae.