Abstract: The apparatus for determining an impulse response in an environment in which a speaker and a microphone are placed works using an audio signal. Means for spectrally coloring a test signal, which preferably is a pseudonoise signal, works using a psychoacoustic masking threshold of the audio signal to obtain a colored test signal, which is embedded in the audio signal to obtain a measuring signal, which can be fed to the speaker. Means for determining the impulse response preferably performs a cross-correlation of a reaction signal received via the microphone from the environment and the test signal or the colored test signal. With this, an impulse response of an environment may also be determined during the presentation of an audio piece to provide an optimal description of environment for a wave-field synthesis.

Abstract: An apparatus for suppressing feedback in an environment where a microphone and a loudspeaker are located, comprises a means for embedding a test signal into a loudspeaker signal, a microphone signal or a modified microphone signal, preferably by using a psychoacoustic masking threshold by using a pseudo-noise test signal, a means for determining a characteristic of a transmission channel in the environment between the loudspeaker and the microphone by using the embedded test signal and the microphone signal, a filter for filtering the loudspeaker signal to obtain a filtered loudspeaker signal, wherein the filter is adaptable to be adapted with regard to its filter characteristic to the characteristic of the transmission channel by the means for determining, as well as a means for subtracting the filtered loudspeaker signal from the microphone signal to obtain the modified microphone signal, in which the feedback is reduced due to the loudspeaker signal.

Abstract: Devices and methods for generating encrypted data, for playing encrypted data and for re-signing originally signed encrypted data are based on the encrypted data, apart from the encrypted media information, to include the information required for decrypting the data and additionally a signature of who has generated the encrypted data. Thus the origin of the encrypted data can be traced back. In particular, passing on the encrypted data to a limited extent by the producer of the *encrypted data, for example to friends or acquaintances, is allowed, while only a mass reproduction of the encrypted data is considered as pirate copying. The pirate copier can, however, be found out with the help of the signature, wherein the signature is optionally protected by an embedded watermark signature. Because this is a concept wherein, when being used legally, only encrypted data occur, the unauthorized removal of the encryption is a statutory offence.

Abstract: For embedding watermark information into an information signal including audio and/or video information, first of all a synchronization sequence with a plurality of synchronization sequence units and a data sequence with a plurality of data sequence units are provided, wherein between the data sequence and the synchronization sequence a time shift is present and wherein a degree of shifting depends on the watermark information. A combination means generates a combination sequence having a plurality of combination sequence units from the synchronization sequence and the data sequence shifted with regard to the synchronization sequence, wherein the combination sequence units are derived from synchronization sequence units and shifted data sequence units. The combination sequence is combined with the information signal in order to embed the watermark information into the information signal.

Abstract: Prior to embedding a watermark in an audio signal, a spectral representation of the audio signal and a spectral representation of the watermark signal are determined. The spectral representation of the watermark signal is then processed on the basis of a psychoacoustic masking threshold of the audio signal. The processed watermark signal is combined with the audio signal to obtain an audio signal bearing a watermark.

Abstract: In a coding method and a coder for introducing a non-audible data signal into an audio signal, the audio signal is first transformed to a spectral range and the masking threshold of the audio signal is determined. A pseudo-noise signal and a data signal are provided and multiplied with each other so a to provide a frequency-spread data signal. The spread data signal is weighted with the masking threshold, and thereafter the audio signal and the weighted data signal are superimposed. In a method and a decoder for decoding a data signal introduced into an audio signal in non-audible manner, the audio signal is first sampled and thereafter the sampled audio signal is filtered in non-recursive manner. The filtered audio signal is subsequently compared to a threshold value so as to retrieve the data signal.