The technologies involved in providing inter-room sound isolation aren't exotic/unknown in general (due to significant demand from some types of office-style co

The technologies involved in providing inter-room sound isolation aren't exotic/unknown in general (due to significant demand from some types of office-style commercial buildings and upscale/premium apartments/condos), nor do they exceed the familiar capabilities of your normal stud-framed wall crew that regularly does insulated exterior/garage-facing walls. So as long as you're in a place where common construction crews have regular experience building thermally insulated stud-framed walls, you'd at most have to look for an architect that has experience designing cross-tenant sound isolation who is otherwise a suitable choice for designing the kind of home you desire. Their existing experience allows to get decent economics for the design workload of even your one-off non-catalogue customization. And considering there are few differences between sound isolation and thermal isolation (except that heat can also be stopped by IR-opaque foam rolling in for air pressure in the evacuated space between two foils (AFAIK that is much better at shielding heat flux than sound's pressure waves, due to the inherent concentration of air pressure into the stiff foam, as there is no gas pressure inside the pores to handle static air pressure forces, while heat conduction doesn't focus like it and heat radiation is interrupted by the opaque foam walls that act as "vacuum super insulation"[0]), and sound can also be stopped by thick heavy stone walls), the architect would at most spec slightly different insulation and likely somewhat different mounting brackets/pads for connecting the drywall to the frame. The end result is no need for non-trivial engineering that a local architect should be able to satisfyingly do from experience, and a design that is just a little weird in overall layout/structure, instead of exceeding the construction crew's scope of experience in any particular detail. [0]: https://en.wikipedia.org/wiki/Multi-layer_insulation https://en.wikipedia.org/wiki/Multi-layer_insulation