[Pseudoscience-is-malarkey (OP)]

Are there ways to build sound proof "booths" in our home without spending hundreds or thousands of bucks? It's an issue of narrating videos for me.

Best

[alancalverd]

Alternating layers of dense (brick, concrete or plasterboard) and energy absorbing (polyurethane foam) materials should help, but the final trick for narration would be to use a noise-cancelling microphone. Small ones are designed for headsets in very noisy environments where fidelity is less important than clarity of speech, so they tend to peak around 5 kHz, but some aspire to broadcast quality. Also consider a semicircular "mike guard" used to isolate vocal mikes from instruments in live studios.

If your final inner wall layer is soft it will suppress paper rustle and chair squeaks but give a very "dead" sound, so you might want to add a hint of electronic reverberation to make the voice sound real.