 Despite modern hearing aids such as cochlear implants, speech comprehension during telephone conversation is challenging for hearing-impaired patients. On the one hand, conventional telephones transmit a limited spectrum of the acoustic signal compared to a normal conversation. On the other hand, lip reading during a phone call is generally not possible. As a result, speech comprehension during a telephone conversation is reduced. In previous studies, the authors demonstrated an improved speech comprehension for hearing-impaired patients using voice-over internet protocol VoIP telephony Skype compared to conventional telephony. 