This Standard is to be used for testing the speech intelligibility of text-to-speech systems, providing a measure of human listeners’ recovery of words that correspond to the intended phonemic content of speech created by the system. Listeners are tasked to record the words or sentences they hear. Scoring may be either at the word or segment level. A normalized edit distance of the response from the intended message is the measure of the system’s speech intelligibility. This Standard specifies methods for selecting test material, which may depend on the purpose and constraints of the test. The Standard also specifies methods for selecting and training the listeners; for designing, controlling, and reporting the test conditions; and for analyzing and reporting the test results. The Standard also provides background material, important for designing the test. Informative software is provided to assist the user in creating stimuli and scoring the test results. Use of the software is not mandatory.