Discrete Cosine Transforms in a radix-2 block transform method enables true split and merge transform processing of equal sized data halves in the transform domain for enabling recursive merges and splits in transform domain without data degradation. The application corresponding to the speaker B is the application executed during communication with the speaker B previously. The positioning portion includes a positioning hole and a second pillar made of a soft material, and either ends of the first pillar are connected to a separate nose pad, and one end of the second pillar is connected in between the two ends of the first pillar. Furthermore, the first protective film is an alumina film; in contrast, the second protective film is a film made of an alumina film containing silicon oxide therein. Direct detection is accomplished according to the equation:I=A+B cos \u03c61\u2212\u03c62+2\u03c0t,with the phase shift difference \u03c61\u2212\u03c62 between two paths containing the acoustic phase information and the frequency f1\u2212f2 being the difference between the RF frequencies for the two acousto-optic modulators.