Subvocalization is the act of silently pronouncing words as you read or think. It can be a major obstacle to reading fluency and comprehension, as it can slow you down and make it difficult to focus on the meaning of the text. There are a number of things you can do to avoid subvocalization, including:
Using a finger or a pointer to follow along with the text as you read. This will help you to keep your focus on the words and avoid the temptation to subvocalize.