National Geographic Readers: Day and Night Readers Ser. by Shira Evans 0 Copyright Year: 2016 ISBN-13: 9781426324703 Available format(s): VOICEText (H) Log in to read What's an Audio Format Audio format refers to the way an audiobook is recorded. Not all audiobooks have the same formats. Classic Audio: A human reading an audiobook without the text displayed. VOICEtext (H): Human narrator with text that you can follow along with as it reads. VOICEtext (S): Synthetic voice with text you can follow along with as it reads.