Ronaldus Maria Aarts

Device for indicating a probability that a received signal is a speech signal

A probability indication signal VP indicates the probability that the audio signal received via the input is a speech signal. An analyzing circuit derives (NA) which is indicative of the ratio between a signal power in a first portion of a frequency spectrum of the received signal and a signal power in a second portion of the frequency spectrum. A signal pattern detector detects signal patterns in the analysis signal (NA) in another signal, for example, a music signal. An estimator derives the probability indication signal VP in dependence on the detected signal patterns.

Signal processing circuit including a signal combining circuit stereophonic audio reproduction system including the signal processing circuit and an audio-visual reproduction system including the stereophonic audio reproduction system

A signal combining circuit has a first input and a second input for receiving signals which have frequencies in the audio frequency spectrum, and an output. A first signal path between the first input and the output has a first transfer characteristic (H1.H3). A second signal path between the second input and the output has a second transfer characteristic (H2.H3). The transfer characteristics are different which causes a phase shift to occur between signal components passed through the first signal path and signal components passed through the second signal path. The amplitude transfer determined by the transfer characteristics decreases above a predetermined frequency. There is a phase difference between phase transfer characteristics which decreases with frequency. For frequencies below the predetermined frequency the amplitude transfer determined by the first transfer characteristic exceeds that determined by the second transfer characteristic. By interconnecting the first input and the second input, the amplitude transfer ((H1+H2).H3) between the interconnected inputs and the output as a function of frequency is substantially constant. The signal combining circuit is used in a stereophonic audio reproduction system to enhance the stereo image. The stereophonic audio reproduction system can form part of an audio-visual reproduction system.