Reading your manuscript aloud, before sending it to the publisher, is a good way to self-editing. You can discover spelling or grammatical errors, if any, before anyone else does, and it can give you new confidence in the power of your writing.
After reading my last manuscript aloud, it was the most empowering experience of my writing career. I was experiencing what my readers would experience in reading my work. Reading aloud was easier for me to pinpoint what I hated about my story; Did I like what the characters were saying and doing? Did their actions seem real, and were their actions believable? Was the pacing too fast? Did the story flow over the pages too fast? Would the reader care what happens next in the story?
Most readers don't care how the book is going to end. They want the emotional experience that they get from the tension and conflict that we create. They want an emotional high. If what we create does not grab us, it won't grab our readers.
After reading my manuscript aloud, I have allowed a few influential people, (agents) to read my manuscript, and they've responded with phrase for my work. Hopefully, my readers will do the same.