On a mounting substrate 101, an LD element 102 and a wavelength converter element 103 are mounted as optical elements. This invention also relates to the production of polyurethane materials in which the isocyanate-reactive component comprises these polypolyols. The anterior refractive optical element and the membrane define an enclosed cavity configured to contain a fluid. In one embodiment, a single voice analysis platform is used to measure voice quality of a voice communication system.