Speech quality evaluation of hands-free telephones during double talk: New evaluation methodologies

During the past years auditory test procedures-conversational tests, listening tests and double talk tests- have been developed in order to quantify the speech quality of hands-free telephones subjectively. This auditory test results are the basis for instrumental evaluation of hands-free telephones. They allow the creation of test procedures as well as the determination of performance parameters and limits. The following paper describes objective test parameter specifically for the double talk situation which is the most critical one for hands-free telephones and requires the most advanced analysis technique. Using the example of one hands-free telephone, the test methodology is described.