Can you sell an echo?

I'm curious, can one actually sell an echo? It's an intriguing concept, isn't it? Echoes are the result of sound waves bouncing off surfaces, creating a repeated sound. They're not tangible objects like a painting or a sculpture, so how could one put a price on them? And if it's possible to sell an echo, what factors would determine its value? Is it the location where the echo occurs? The clarity and strength of the sound? Or perhaps it's something entirely different? It's a fascinating question that raises plenty of interesting points to ponder. So, can you really sell an echo, and if so, how would one go about it?