Well, I can only assume they have no bass; “nano” seems to imply less than woofer-level low-end. It seems that researchers at Tsinghua University in China have created a “speaker” that can transmit sound as well as conventional speakers, but without magnets or any moving parts whatsoever. They’re made from films of carbon nanotubes and are lightweight, transparent, and “tens” of nanometers thin (probably that’s as precise as quantum mechanics allows them to get). Interestingly, the film actually doesn’t vibrate or move at all. The pressure waves composing the sounds are created by temperature fluctuations, if I understand correctly (unlikely). Furthermore they produced sound whether they were bent, moving, or even partially damaged.
They’re currently manufactured up to a maximum width of 10cm, but a 4-in. wafer can be “stretched” to 60m long, providing enough speaker material to make 500 10x10cm loudspeakers. It’s all in the lab right now, of course, but this technology sounds really promising and fundamentally different. Hopefully we’ll be hearing more from them in the future.