A method for processing speech in a spread spectrum communication system uses CELP speech encoded signals. A flattened area can be located between the flank surfaces. The pair of glasses comprises a first filter and a second filter, the first filter transmitting the entirety of the spectrum except a first narrow spectral band centred on the first wavelength and the second filter transmitting the entirety of the spectrum except a second narrow spectral band centred on the second wavelength. The arterial and venous patient connectors, and the arterial and venous unit connectors, are respectively, substantially, and releasably directly connected to each other. The radio wave interference warning is erased when the cause of the radio wave interference disappears. Additional information can be encoded in the serial bit stream by selection among redundant codes based on the value of the additional information.