Ecommerce Solution Architect @Sitecore, music lover and photography enthusiast. Opinions are my own.
In other words, moderate audio inputs help keep our idea gateway open during the generative phase of creative problem solving so as to maximize the opportunities for reaching a final solution in the convergent phase.
As a point of reference, 70db is the rough equivalent of the din at a bustling restaurant or coffee shop. It also approximates the loudness of a running shower, which is probably one reason why we so often get good ideas while under the spigot.