I don't know the teaching well enough to explain the reasoning behind the understanding that reading is considered the same as hearing, that you are actually using the same faculties to 'listen' when you're reading than you do when you're just 'looking' or 'seeing.' So, the summary is that listening to something is the same as reading something. The teaching involved a lesson that, when considering a potential spouse, it is better to speak to them on the phone a few times rather than in person because our sight gets in the way of 'hearing,' but this is not the case when actually just listening. Advertising relies on this reality and throws images into their message to take advantage of the better odds of persuading you through the use of images and if you only listened to the message, you'd be less inclined to being deceived.