ETSI TR 103 225 provides a review of existing test methodologies to assess speech intelligibility, quality and listening effort.

It should be noted that most test methods (for quality or intelligibility) have been developed with normal hearing people and that there is a lack of data for hearing impaired people.

Some clauses of the present document provide a review of existing methods or test results that take into account couplings between phones and listener's ears (acoustical coupling), and coupling between phones and hearing aids (inductive, acoustical or via radio links). Different hearing impairments affecting the listening performance are also considered.