Described herein are techniques for determining corresponding positions between different representations of a textual work. In some of the techniques, portions of one or more representations may be processed. A determination of a corresponding position may be made in response to a request received from a user, such as a reader that desires to switch between representations. The request may indicate a position in one representation and the representation to which the user would like to switch. In response to receiving the request, one or more portions of one or more representations of a textual work may be processed. In some techniques, a corresponding position between different representations may be determined without processing the entirety of one or more representations of the textual work. For example, a corresponding position may be determined without processing an entire audio representation.