Clinical Single Centre Cohort Study Comparing Telephone vs. Voice Over Internet Protocol (VoIP) Speech Comprehension for Acoustical and Bluetooth Speech Signal Transmission in Hearing Aided Subjects.

Speech comprehension of hearing impaired individuals is limited in telephone conversations due to the limited acoustic spectrum transmitted by conventional analogue telephones, such as background noise, interferences with the hearing aid and the absent possibility of lip-reading. This can provide an impact on quality of life as better speech comprehension reduces exclusion from social interactions as well as potential professional occupations. Furthermore, in elderly population an impaired hearing function is associated with a higher risk of dementia, mortality rate and dependency in the daily activities.

Mantokoudis et al. recently demonstrated that the larger acoustic spectrum of internet telephony (Voice over Internet Protocol [VoIP]) results in superior speech comprehension of individuals with hearing aids compared to conventional telephones. Low signal quality during internet telephony does not significantly attenuate speech understanding. Another study revealed that internet telephony combined with a webcam further improves speech comprehension as additional lip reading was possible.

New bluetooth audio streaming devices allow for pairing with smart phones or other devices supporting bluetooth technology such as computers for direct routing of the audio signal to the hearing aid. Current state of research shows significant benefits for hearing impaired individuals using this technology for telephone conversations. The speech comprehension and subjective satisfaction can be improved due to a better sound quality and accuracy and less noise interference.

However, speech comprehension of these new bluetooth devices has not been investigated in combination with internet telephony (VoIP) and it remains unclear whether hearing impaired individuals could benefit of this possibility. This study investigates, whether bluetooth audio streaming devices paired to hearing aids/implants combined with internet telephony improves speech comprehension in hearing impaired individuals.

VoIP and conventional telephone speech comprehension will be compared with and without a wireless bluetooth phone clip (Cochlear Wireless Phone Clip, Cochlear Ltd., 1 University Avenue, Macquarie University, New South Wales 2109, Australia). The phone clip is capable to directly connect to other bluetooth-enabled devices and transmits the audio signal directly to the sound processor of the hearing implant. A microphone in the phone clip enables to record and transmit the user's spoken words to the mobile phone therefore a hands-free use is possible.