Musical instruments on the nanoscale.
Although the first nano-guitar dates back to the early Information Age, serious production of nanomusical instruments did not come into vogue until some centuries later.
These included and include nano instruments, with nano mikes, and nano FX. Imagine a sound system plug-in for nanoFX, similar to a rotary speaker or a vibraphone which uses rotating cups over the tubes to get that washy underwater sound. Another popular option are tiny floating nanonic devices moving in specific orbits and recording the same instrument in a variety of positions changing regularly and then amplifying it.
Also of importance are nanoamps. Rather than having a large speaker stack arranged in a surround-sound as in olden day macroscale music, these enable specific adaptable bio-diaphragms or walls/curtains of nano material that can simulate this or indeed any other effect. So a simple voice/thought command draws a translucent, permeable curtain across a space and effortlessly and perfectly emulates the exact acoustics of NuiCarnege Hall, Eden, or other presets. Alternatively you can tweak them which ever way you want. And if you want to leave the room you get to enjoy the experience of 'walking thru music'.