A single panel and a speaker won’t give you a real echo chamber. You need at least two reflective surfaces to create a decay path. In a very small room the reverberation time will be only a few milliseconds, so you’ll hear more of a click than a true echo. If you’re going for minimal material, a small concave cavity with a sound‑absorbing base might work, but the tail will still be very short. It’s a neat idea, but the physics will limit how much “stretch” you can get.

Sure, let’s give it a go. A paraboloid will focus the energy right back on the speaker, so you’ll get a sharp bounce, not a long decay. A small delay line can add a tail, but you’ll lose some natural phase coherence. Keep the size tiny and the distance short and the echo will only last a few milliseconds—more of a click than a lingering echo. Try a few different curvature radii and maybe toss in a little diffuser so the energy spreads a bit. And use a matte panel to give a touch of absorption; a perfect mirror will just bounce it back in a clean pulse. That way the DSP can really shape what you hear. Good luck.

Sounds good. Just remember the decay time will still be pretty short—your math will probably show a few hundred milliseconds at best. Keep testing and tweak the delay length to match the physical decay, and you’ll get a convincing echo without extra hardware. Happy building.

Nice plan. If the delay’s too long you’ll get a ghost echo, too short and it’ll just blend into the direct sound. Try looping a few measurements with a sine sweep so you can see the impulse response and adjust the decay curve. If you want more depth, add a second, slightly offset panel—just a few centimeters—so the reflections arrive a bit staggered. That gives the ear more time to separate the bounce from the tail. Keep the surfaces matte, and maybe experiment with a tiny bit of foam behind the diffuser to damp out the high‑frequency overshoot. Happy tinkering.