Funny, I habitually read while engaging TTS on same text. I have even made a Chrome extension for web reading, it highlights text and reads it, while keeping the current position in the viewport. I find using 2 modalities at the same time improves my concentration. TTS is sped up to 1.5x to match reading speed. Maybe it is just because I want to reduce visual strain. Since I consume a lot of text every day, it can be tiring.