Inter- and Intra-individual Variation in Applied Force When Listening at a Surface, and Resulting Variation in Earprints

Abstract

We aimed to explore the level of inter- and intra-individual variation in applied force when listening at a surface, and assess the resulting variation in earprints. We further intended to identify possible sources of this variation. Forty subjects each listened twenty-four times at a surface while applied force was recorded. In between efforts the level and frequency of the target sound, and the level of ambient noise were varied. Each listening effort was characterized by two values: the mean of a series of force recordings ('functional force') and the highest force reading of the effort ('peak value'). A mixed model analysis of variance revealed that repetition during multiple efforts of listening and the level of the target sound significantly affected both values for applied force. The frequency of the target sound affected the peak value, but we assume this was due to confounding effects. The level of ambient noise did not affect applied force. To explore the correlation between values for applied force of various efforts by single ear, the intra-class correlation coefficient was calculated. For functional force it was 0.80; for the peak value it was 0.79. To study intra-individual variation in earprints, five prints from each ear were lifted and studied. Variation in prints is discussed.

A survey on ear biometrics

“…-Variable deformations are caused by the force applied by the ear to the surface during listening [Meijerman et al 2004[Meijerman et al , 2006a; -There is duration of the ear's contact with the surface [Meijerman 2006]; -There are ornamental modifications to the ear, such as piercing [Meijerman 2006]; -Changes in the shape and size of the ear come due to aging [Meijerman et al 2007]. …”