Apparently @Samurai asked Dreamweaver about the field on the live chat.
Please see this post.
I would say listening to it 3 times would last at least a few weeks, depending on how quickly the cells renew. Damaged cells repair quicker, so the effect in that case would last a shorter amount of time. Yes, the effect should last until cell death.
According to this article, an average skeletal muscle cell’s lifespan is 10 to 16 years, however, I’m not sure how accurate this information is.