We offered 1/4" and 3/8" thick acrylic inserts for sound abatement from 2008 to 2011. But we decided to discontinue it as a primary product because it disappointed too many of our customers who had mid-to-low frequency noise/sound problems, i.e. big trucks, big motorcycles, big dogs, train rumble, a/c units, etc. It just didn't stop enough airborne noise. Our laminated glass inserts worked much better. We only use 1/4" acrylic in special cases, i.e. when the soundproof insert is required to bend.
When we started producing soundproofing window inserts, we looked for four basic characteristics in choosing materials: Clarity, Mass, Manufacturing Suitability and Cost. That leaves us with two basic choices of material: plastic and glass.
Of the plastics, acrylic was:Pros: Clear, easy to work with and reasonably priced.Cons: Low mass and scratches easily.
Of the types of glass available, laminated glass was:Pros: Clear, has high mass and has an interlayer that prevents it from vibrating with sound.Cons: Very difficult to manufacture and is expensive.
Hence, acrylic was chosen as the low-cost option, and laminated glass was the expensive option.