Hearing-Impairment Clinical Trial
Official title:
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.
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.
New bluetooth-enabled hearing aids allow for direct transmission of the telephone signal to
the hearing device. As the direct transmission is expected to improve signal-to-noise ratio,
speech comprehension is tested in patients with bluetooth-enabled hearing aids for 4
different scenarios: 1. conventional telephony without bluetooth device 2. conventional
telephony with bluetooth device 3. VoIP telephony without bluetooth device 4. VoIP telephony
with bluetooth device
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.
Bluetooth connection is a well-established wireless technology transmitting at 2.4 gigahertz
at distances up to approximately seven meters. The wireless technology is the same for most
of bluetooth and Wireless Local Area Network (WLAN) devices. According to the Swiss federal
health office the electromagnetic radiation of the bluetooth device as intended to be used in
the proposed study fulfils the requirements of the European Committee for Electrotechnical
Standardization (CENELEC).
Several previous studies demonstrated a significantly increased conventional telephone speech
perception with the Cochlear Wireless Phone Clip than without this device. On the other hand,
speech perception in hearing impaired people using internet telephony is improved compared to
conventional telephony. However, speech perception using the phone clip in connection to
internet telephony has not been studied to this date and remains unknown.
The purpose of the proposed study is to quantify VoIP vs. conventional telephone speech
comprehension in individuals with or without application of bluetooth phone clip. Potentially
better speech comprehension due to the application of the phone clip could alleviate the
handicap of communication in individuals with hearing aids. As a consequence the social life
and contacts of the affected individuals such as worsening of mental state and dependency in
the everyday life could be ameliorated only by using a simple device.
The goal of this study is to measure speech comprehension of individuals with hearing aids
using a bluetooth paired phone clip and VoIP telephony. To quantify a potential benefit of
this, speech comprehension has to be tested with and without the phone clip for VoIP and
conventional telephony in the same individuals. Speech comprehension will be quantified with
a signal/noise ratio of the HSM- sentence test (Hochmair, Schulz, Moser)
Upon agreement to participate, patients are invited to the audiological department at
Inselspital in Bern. After remaining questions are clarified, the patient has to sign a
written informed consent. The investigation will take approximately two hours and takes place
in the sound-proof hearing test chambers of the audiological department.
Four different speech comprehension scenarios are tested:
1. Conventional telephony without bluetooth device
2. Conventional telephony with bluetooth device
3. VoIP telephony without bluetooth device
4. VoIP telephony with bluetooth device
To evaluate speech comprehension, the HSM (Hochmair-Schulz-Moser) sentence test is used. This
is a test mainly applied to evaluate the speech comprehension in patients with cochlear
implants and consists of 30 lists each including 20 short sentences. After initial
presentation of exercise sentences without background noise, additional noise is added while
the speech signal is kept at a constant volume level. The percentage of speech comprehension
is determined by the quantity of correctly understood sentences at a certain signal-to-noise
ratio (S/N Ratio). In this study a S/N Ratio of 10dB, with a signal at 70dB and noise at
60dB, will be analysed.
For representativeness of speech comprehension results, participants will use their hearing
aids with their daily use volume settings. The phone clip will be programmed for a 1:1
transmission of the telephone conversation and the ambient noise. At the end, the patient has
to evaluate the subjective perception of the speech sound quality by means of the Mean
Opinion Score (MOS).
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