Fig. 6: Two different multi-user channel conditioning scenarios.
From: Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces
a–c A configuration of two loudspeakers (Spks.) and six microphones (Mics.), which is described by 6 × 2 channel matrices. a The desired effect is to separate the microphones into two groups, each group detects the sound from only one loudspeaker. b Channel matrices before (left) and after (right) the optimization. c The time-domain signals received by microphones 1–6. The desired signals are enhanced by an average of 2.9 dB, and unwanted signals are suppressed by 9.7 dB. d–f A configuration of two loudspeakers and four microphones, described by 4 × 2 channel matrices. d shows the desired effect. e Channel matrices before (left) and after (right) optimization. f The time-domain signals received by microphones 1–4. The desired signals are enhanced by 2.2 dB on average, and the unwanted signals are efficiently reduced by 15.7 dB.
