Not what you describe, but that reminds me. There are panels that 'cancel' (some of) the noise by guiding the air through foam channels. Had never heard of such

Not what you describe, but that reminds me. There are panels that 'cancel' (some of) the noise by guiding the air through foam channels. Had never heard of such thing before, personally. [0]: https://youtube.com/watch?v=tMLIzedVvH8&t=1031 https://youtube.com/watch?v=tMLIzedVvH8&t=1031 (timestamp included)