Can curtains provide good soundproofing?
One of the rules of soundproofing (sound insulation or sound isolation if you prefer) is that sound is best blocked by reflection, using a barrier of high mass. Bricks, high-density blocks, concrete and plasterboard (gypsum board) are all good. So is thick glass. Particle boards are useful too in sufficient thickness.
If you were aiming for near-total soundproofing, then reflection is the way to go. But it is costly, disruptive to install, and small defects in construction can cause a significant loss of performance. There is a strong case to be made for calling in professionals with experience in recording studio construction. That's going to cost.
But you can take the view that whatever the existing level of soundproofing in your studio, whether it is a bedroom, garage or shed, it can be improved to a useful extent at a relatively low cost and with little disruption.
Small improvements can be very worthwhile, especially if they don't cost too much.
Now you might think that curtains couldn't possibly provide good soundproofing. After all, they are relatively lightweight, and some sound energy is bound to avoid them simply by going around the edges.
But that isn't the point. They don't have to provide perfect soundproofing. They just have to make things better at a reasonable cost. The technical documentation on Quiet Curtains' website is impressive. And the price compares well to quality curtains custom made.
I'm not normally convinced by mere claims of performance, I like to see and hear the evidence for myself. And I do have some experience of curtains and soundproofing...
A year or so ago I bought some blackout curtains for the same reason anyone would buy them - to keep my bedroom dark until a reasonable hour during the summer months. I was surprised that a label on the packaging claimed that they also provided soundproofing. Nonsense, I thought, they're nowhere near thick enough or heavy enough.
I live within earshot of a road that is busy from early in the morning, and I can hear it in my bedroom. Not too loud, but it's there. But when I installed the blackout curtains, I was amazed at the difference in the subjective level of the noise from the road. If I had made a measurement, I doubt if it would have amounted to even a couple of decibels across the whole frequency band. But the difference at high-mid and high frequencies was clearly audible.
As I said earlier, perfection in soundproofing is expensive, and is often unattainable. Good soundproofing is also hard to achieve. But a difference in the level of soundproofing that makes a small but useful improvement can be surprisingly easy to achieve and - significantly - not cost too much.
P.S. The same applies to acoustic treatment, but that's another story.