The auditory perceived quality of hands-free telephones: Auditory judgements, instrumental measurements and their relationship

In this paper quality evaluation procedures for hands-free telephones are described with reference to some examples. The paper shortly describes the hearing tests conducted in order to investigate the auditory perceived quality in single talk condition. The parameters found to be most relevant in this situation are listed. Special tests were conducted in order to evaluate the conversational quality of the systems. The parameters found to be most interesting are listed as well. Instrumental measurements, showing procedures for instrumental evaluation are shown using the examples of the different hands-free telephones. As a consequence from the auditory evaluation a classification of different types of hands-free telephones is proposed. For each class of hands-free telephones the relevant instrumental measurement parameters are listed.