1. A method performed by a computer processor executing computer program instructions tangibly stored on a first computer-readable medium to perform a method comprising steps of: (A) deriving, from a region of a document and a corresponding region of a spoken audio stream, a likelihood that the region of the document correctly represents content in the corresponding region of the spoken audio stream; (B) selecting a measure of relevance of the region of the spoken audio stream, the measure of relevance representing a measure of importance that the region of the spoken audio stream be brought to the attention of a human proofreader; and (C) deriving, using the processor, from the stored representation of the likelihood and the stored representation of the measure of relevance, an emphasis factor that modifies emphasis placed on the region of the spoken audio stream when played back, wherein (C) comprises: (C)(1) identifying a rule that identifies the emphasis factor based on the identified likelihood and the identified measure of relevance; and (C)(2) applying the rule to the identified likelihood and the identified measure of relevance to derive the emphasis factor; where (C)(2) comprises: (C)(2)(a) identifying a first weight associated with the identified likelihood; (C)(2)(b) identifying a second weight associated with the measure of relevance; and (C)(2)(c) deriving the emphasis factor from a combination of the identified likelihood and the measure of relevance weighted by the first and second weights, respectively.