What is the most effective material type for preventing sound transmission?

The most effective material type for preventing sound transmission is drywall with insulation. This combination works well because the insulation material within the wall cavity significantly reduces the transmission of sound waves. Insulation absorbs sound, helping to diminish its travel through walls and ceilings, thereby minimizing noise issues between rooms or from external sources.

While other options might offer some degree of soundproofing, they do not effectively combine the properties necessary for optimal sound reduction to the same extent. For instance, a cavity wall can provide a barrier to some noise due to the air space within, but it lacks the added absorption capabilities that insulation offers. Similarly, while a double wall can create a more substantial barrier, it often requires careful design to ensure air gaps do not negate its benefits. Gypsum board itself has limitations in soundproofing when used alone, as it does not provide the same level of sound absorption as drywall combined with insulation does.

Overall, the combination of drywall and insulation addresses both mass and absorption, which are critical factors in soundproofing, making it the most effective choice in this context.