Sound waves travel through solids by causing vibration. The more mass the solid has, the harder it is to move, thus reducing the amount of vibration and sound that is transferred.
Between a piece of acrylic and a piece of glass that are both the same thickness, the glass will be denser and weigh more. The glass will provide better soundproofing since it’s harder to vibrate and thus harder for sound to transfer.
STC stands for sound transmission class. It’s a measurement of how well different materials block sound from transferring. The higher a product’s STC rating, the more effective it is at soundproofing.
Laminated glass has a higher STC Rating than the equivalent thickness of acrylic so it will provide lower sound transmission or better noise reduction at all thicknesses.
A more resilient material will last longer and provide years of worry-free service. Laminated Glass is both break resistant and scratch resistant and it is installed with heavy-duty aluminum window frames. Acrylic is plastic so it tends to scratch easily and it is usually installed with simple magnets.
Laminated glass is, therefore, more resilient and durable than acrylic.
Windows are designed to provide light and ventilation.
Laminated glass is installed with actual windows that operate like your existing windows. They are designed and built to match the existing windows. They are easily open and close. Acrylic is generally large fixed panels attached over existing windows with magnetic tape. They do not operate.
Laminated glass windows allow much greater use of your existing windows than acrylic.
Overall Acoustical Laminated Glass is the best choice for maximum soundproofing.