摘要:
A conference system (1) comprises a central unit (2) and speaker units (3) which are connectable to the central unit. The central unit (2), which serves to combine speech signals from the speaker units (3) and to distribute the combined speech signals to said units, comprises an adaptive filter (23) for suppressing feedback. Each speaker unit (3) comprises a microphone (33), a loudspeaker (34), an activation switch (35) and an adaptive filter (36) coupled between the microphone (33) and the loudspeaker (34). When the speaker unit is not activated, the adaptive filter (36) serves as an echo canceller, while serving as a feedback suppressor when the speaker unit is activated. By keeping the loudspeaker (34) always on, any transients due to mis-adaptations of the filter (36) are avoided.
摘要:
A digital image (110) which is displayed to a user (118) is modified to include an aspect (120) of a detected at least one characteristic of the user (118) to give the user (118) the impression that the user (118) is present within the scene displayed by the digital image (110).
摘要:
A method is provided which is suitable to cope with non-linear echo paths during acoustic echo cancellation in speakerphones. Non-linear paths occur particularly in hands-free operation of, e.g., a mobile phone, due to driving the amplifier and loudspeaker in the non-linear range. The idea is to combine the commonly known one microphone approach of linear acoustic echo cancellation using an adaptive filter and a post-processor together with a multiple microphone approach using beam forming which separately removes the non-linear part of the echo.
摘要:
A signal processing system comprises a microphone (20), a subtractor (22) arranged to receive an output of the microphone (20), an amplifier G arranged to receive an output of the subtractor (22), a rear loudspeaker (24) arranged to receive an output of the amplifier G, a front loudspeaker (26) arranged to receive an output of the amplifier G, and one or more summers (28) interposed between the amplifier G and a loudspeaker (24, 26), the or each summer (28) arranged to add an audio signal m[k] to the signal s[k] received from the amplifier G. The system also includes a mixing matrix D arranged to receive the respective inputs R, F of the rear and front loudspeakers (24, 26) and arranged to output a summation signal R+F and a difference signal R−F, and an adaptive filter SAF; MCAF arranged to receive the outputs R+F, R−F of the mixing matrix D, the subtractor (22) arranged to receive an output of the adaptive filter SAF; MCAF and an output of the subtractor (22) arranged to control the adaptive filter SAF; MCAF.
摘要:
A sound reinforcement system includes several microphones, a microphone beamformer coupled to the microphones, adaptive echo compensator (EC) coupled to the microphone beamformer for generating an echo compensated microphone signal, and several loudspeakers coupled to the adaptive EC. An adaptive loudspeaker beamformer is coupled between the adaptive EC and the loudspeakers for shaping the directional pattern of the loudspeakers. The adaptive loudspeaker beamformer creates a beam pattern which is capable of creating a “null” in the direction of speaker(s) such that howling is effectively prevented.
摘要:
The invention proposes extracting one or more speech signals (151-154) as well as one or more ambient signals (131) from sound signals captured by microphones, wherein each of the speech signals corresponds to a different speaker. The invention proposes to transmit both the one or more speech signals (151-154) and the one or more ambient signals (131) to a rendering side, as opposed to sending only speech signals. This enables to reproduce the speech and ambient signals in a spatially different way at the rendering side. By reproducing the ambient signals a feeling of “being together” is created. In an embodiment, the invention enables reproducing two or more speech signals spatially from each other and from the ambient signals so that speech intelligibility is increased despite the presence of the ambient signals.
摘要:
An earphone arrangement comprises a microphone (109) which generates a microphone signal and a sound transducer (101) which radiates a first sound component to a user's ear (103) in response to a drive signal. An acoustic channel (111) is further provided for channeling external sound so as to provide a second sound component to the user's ear (103). An acoustic valve (117) allows the attenuation of the acoustic channel (111) to be controlled in response to a valve control signal. A control circuit (105) generates the valve control signal in response to the microphone signal to provide a variable attenuation resulting in a mixed sound of the first sound component and the second sound component reaching the user's ear (103). The combined use of acoustic and e.g. electric signal paths allows improved performance and in particular allows a dynamic trade-off between open and closed earphone design characteristics with respect to external sounds.
摘要:
A sound source location is estimated by particle filtering where a set of particles represents a probability density function for a state variable comprising the sound source location. The method includes determining the weight for a particle in response to a correlation between estimated acoustic transfer functions from the sound source to at least two sound recording positions. A weight update function may specifically be determined deterministically from the correlation and thus the correlation may be used as a pseudo-likelihood function for the measurement function of the particle filtering. The acoustic transfer functions may be determined from an audio beamforming towards the sound source. The audio weight may be combined with a video weight to generate a multi-modal particle filtering approach.
摘要:
An earphone arrangement comprises a microphone (109) which generates a microphone signal and a sound transducer (101) which radiates a first sound component to a user's ear (103) in response to a drive signal. An acoustic channel (111) is further provided for channeling external sound so as to provide a second sound component to the user's ear (103). An acoustic valve (117) allows the attenuation of the acoustic channel (111) to be controlled in response to a valve control signal. A control circuit (105) generates the valve control signal in response to the microphone signal to provide a variable attenuation resulting in a mixed sound of the first sound component and the second sound component reaching the user's ear (103). The combined use of acoustic and e.g. electric signal paths allows improved performance and in particular allows a dynamic trade-off between open and closed earphone design characteristics with respect to external sounds.
摘要:
The adaptive beamformer unit (191) comprises: a filtered sum beamformer (107) arranged to process input audio signals (u 1, u2) from an array of respective microphones (101, 103), and arranged to yield as an output a first audio signal (z) predominantly corresponding to sound from a desired audio source (160) by filtering with a first adaptive filter (f1(-t)) a first one of the input audio signals (u1) and with a second adaptive filter (f2(-t)) a second one of the input audio signals (u2), the coefficients of the first filter (f1(-t)) and the second filter (f2(-t)) being adaptable with a first step size (a1) and a second step size ((x2) respectively; noise measure derivation means (111) arranged to derive from the input audio signals (u1, u2) a first noise measure (x1) and a second noise measure (x2); and an updating unit (192) arranged to determine the first and second step size (a1, (x2) with an equation comprising in a denominator the first noise measure (x1) for the first step size (a1), respectively the second noise measure (x2) for the second step size (a2). This makes the beamformer relatively robust against the influence of correlated audio interference. The beamformer may also be incorporated in a sidelobe canceller topology yielding a more noise cleaned desired sound estimate, which can be used in a related, more advanced adaptive filter (f1(-t), f2(-t)) updating. Such a beamformer is typically useful for application in handsfree speech communication systems.