A method of estimating the shape of an individual ear includes determining at least part of the shape of the individual ear, the shape being determined over a first extent and constituting a determined shape； taking a predefined template shape determined by statistical analysis of a plurality of previously measured ear shapes according to a statistical model, the template shape having a second extent； and generating an estimated shape corresponding to an estimated representation of the shape of the individual ear over the intersection of the first extent and second extent by modifying the template shape to substantially match the determined shape over the first extent or over the second extent within a predefined tolerance. Also, a method of optimising an ITE shell, BTE or CRT housing, or BTE sound tube to a given population group utilising the same template methodology.
