“…Together with appropriate and consistent auditory-oral therapy they provide severely to profoundly hearing impaired persons with the choice of functioning and interacting in the hearing world more easily. Studies have shown that, provided that the criteria and guidelines for patient selection are observed, they are beneficial for the improvement of voice quality, intelligibility, speech perception and production in prelingually impaired (Tobey, Geers, & Brenner, 1996;Kishon-Rabin et al, 2002;Mildner, Š indija, & Horga, 2003;Calmels et al, 2004) as well as in postlingually deafened children and adults (Matthies & Svirsky, 1996;Ito, Suzuki, Toma, Shiroma, & Kaga, 2002;Välimaa, Määttä, Lö ppö nen, & Sorri, 2002a, b). The effectiveness of cochlear implants is most frequently tested by means of listening and comprehension tests and/or by analysis of the speech of their users (O'Donoghue, Nikolopoulos, Archbold, & Tait, 1999;Richter, Eissele, Laszig, & Lohle, 2002;Houston, Pisoni, Iler Kirk, Ying, & Miyamoto, 2003;Calmels et al, 2004).…”