>>82236471Depends on the noise. The inward-facing spikes reduce echo and keep sound inside from leaking out. Keeping outside sounds from getting in is more difficult. You would want a separate inner layer with the spikes facing the other way I guess?
Even then, it won't reduce low frequency (e.g. deep bass) vibrations nearly as much. That's very difficult to do without sheer mass, or more professional acoustic barriers. Or both.
For blocking outside noise, you're better off with 2-inch panel frames filled with heavy scrap fabric, acquired in bulk, such as towels from charity resale shops (goodwill, etc.). You'll have a harder time mounting than sticking some lightweight foam on the walls, but at least it'll work and you won't have wasted money on the eggshell foam meme.
