Your hours are renewed with each payment and are shared between all profiles. This means that if you listen or read for two hours, and another profile for three hours, you will have used up five hours together.
If you listen to an audio book at normal speed (x1) for one hour, one hour will be deducted from that period. If you play the book faster, e.g. at a speed of 1.5, the time is consumed 1.5 times faster. For example, listening for 1 hour at a speed of x2 counts as 2 hours. If you play the book more slowly, the time is consumed more slowly.
For e-books, a certain number of characters counts as one hour. This means that it does not matter how fast or slow you choose to read. Turning pages quickly or jumping between chapters does not count as time either.
If you read or listen to the same segment of a book more than once in the same period, time is only counted the first time.