Even though the interest in rhetoric does still not recline today and even though the orator's performance was considered the most important element of oratory in antiquity, there has been no detailed piece of research on the voice of the orator in ancient rhetoric so far. This book aims at closing this gap. To achieve this, we need a multi-faceted approach because our sources are extremely disparate, have come down to us in very different contexts and are to some part poorly transmitted. This is why our two main sources - the Auctor ad Herennium, who writes in late Republican times (1st century BC), and Quintilian (1st century AD) - have to be explained in a detailed commentary. Additionally, our shorter rhetorical texts must not be neglected and have to be complemented by texts belonging to different scientific discourses such as medicine, philosophy and grammar. Thus, this book offers two approaches. First, it presents chronologically all the relevant texts dating from the 5th century BC to the 8th century AD and explains them (chapter 2 and 3). Second, it analyses the rhetorical main sources with regard to content, grammar and style (chapter 4). Therefore, depending on the readers' interests this book can be read from a philological, a historical or an interdisciplinary perspective (chapter 5).