Speech quality evaluation of hands-free terminals

This paper describes a new methodology for the speech quality assessment of hands-free terminals and discusses the results of a pilot study performed in 1996 at the Berlin laboratories for speech quality assessment at the Technology Centre of Deutsche Telekom. Up to now, critical speech quality aspects of hands-free terminals are usually assessed with conversational tests. With the test method proposed here, much more efficient listening only tests can be applied to evaluate various speech quality aspects of hands-free terminals. In the pilot study, a series of conversational tests, specific double talk tests and listening only experiments were performed. The paper descibes the recording environment and equipment, the auditory test methodology and the results of the listening only experiments.