This Recommendation¹ describes test signals that are applicable for telephony and other speechbased applications. A wide variety of test signals are given, starting with low complexity test signals, continuing through test signals with a high degree of complexity incorporating many typical parameters of speech. In addition to technical signals, such as sine waves or noise, more speech-like signals are also described.

The overview of typical applications of the described test signals should be considered a guideline in terms of general application rules. However, detailed descriptions of each application should be obtained from the individual Recommendations describing the measurement procedures for each specific application.

To avoid difficulties when creating the described test signals, all of these signals are freely available from the ITU-T test signals database:

¹ This Recommendation includes an electronic attachment containing the set of freely-available test signals described within the Recommendation.