Automatic Gain Control (AGC)
The AGC, also known as automatic gain control, ensures that the microphone signal is always recorded at the same volume. If a speaker is standing further away in the room, the signal entering the microphones is significantly softer than if the person is standing directly in front of the microphone. The AGC automatically compensates for this difference in level without undesirably amplifying quiet background noise.
Beamforming
Beamforming is the technique of combining signals from several microphones into a single one, thereby achieving a desired directional effect towards a specific sound source. By focusing on a speech source in the room, lateral noise is attenuated, and speech intelligibility is increased. What humans can do intuitively (listen carefully) is not a matter of course for machines.
Echo Cancellation
Everyone knows it from phone calls: The person on the other end of the line switches the phone "to loudspeaker" − and suddenly you hear your own voice as an echo. That really disrupts the flow of conversation! The voice signal that comes out of the other person's loudspeaker goes back into the microphone. But a good echo canceler filters out the echo before it is sent over the line. This is no easy task, especially when both partners are speaking at the same time. Our echo cancellation can handle any scenario and is freely scalable, even on any number of loudspeakers and microphone channels simultaneously.
Dereverberation
The natural reverberation of a room can also interfere with phone calls. And the quality of automatic speech recognition also suffers greatly as a result. Blind reverberation suppression, also known as dereverberation, removes disturbing room components from speech and ensures a dry, easily understandable speech signal.
Comfort Noise Injection
"Hello, are you still there?" − many people are familiar with this situation from phone calls. If too much background noise is filtered out during pauses in speech, there is complete silence. This gives the impression that the line is "dead". A good comfort noise injection system fills the pauses in speech with an artificially generated noise that corresponds to the natural background noise in terms of timbre and level, so that the impression of a transparent, open communication channel is created despite the massive removal of background noise.
Fraunhofer Institute for Digital Media Technology IDMT