This Recommendation1 describes test signals that are applicable for several purposes in telephonometry. A wide variety of test signals is given@ starting with low complexity test signals up to test signals with a high degree of complexity incorporating many typical parameters of speech. Besides technical signals@ such as sine waves or noise@ more speech-like signals are described. The overview of typical applications of the test signals described is a guideline giving general application rules. The detailed description of the application@ however@ should be found in individual Recommendations describing the measurement procedures for specific applications. To avoid difficulties when creating the test signals described@ all these signals are freely available for download from the ITU-T test signals database: http://www.itu.int et/itu-t/sigdb/genaudio/Pseries.htm.