Abstract: Source coding digitized audio signals includes providing time or spectral domain sampling values of the digitized audio signal, requantizing the sampling values according their permissible quantizing noise as determined by a coding and requantizing control signal, and multiplexing the control signal and the requantized sampling values into a time multiplex frame depending on the bit rate reduction employed. The coding and requantizing control signal is determined from the sampling values by determining the global masking effect from all relevant maskers which are tonal maskers and noise maskers, and which result from the sampling values, and from a silence audio threshold.

Abstract: A method for controlling a voice-controlled voice direction recognition unit for a digital telephone station, which can be connected to termination units having different hybrid attenuations. The method prevents self-interruption in the transmission side due to an excessively low hybrid attenuation. This is achieved by providing a counter unit that identifies the switching occurrences of the voice direction recognition per time unit and, when a predetermined number is exceeded, that causes the voice direction recognition unit to connect an auxiliary attenuation element into every voice channel. The method can be utilized in digital telephone stations whose termination units are located in an appertaining switching system.