Benefit of Using a Conference Mic with a Cochlear Implant

Question

Answer

Many cochlear implant (CI) users who receive their implant as an adult are very satisfied with the improvement in quality of life.  They report that they manage work and social life better than before they had a CI (Hardeveld, 2012).   Taking part in conversations in quiet surroundings is not difficult. However, speech recognition deteriorates rapidly as the level of background noise increases (Fu & Nogaki, 2005).

Effective communication at work means active participation in discussions or meetings with colleagues who do not have hearing loss. Assisting those who use a CI by passing microphones between speakers can be a challenge that requires discipline and patience from all participants. Discussions are often stilted as conversations pause when speakers wait their turn for the microphone. Placing a conference microphone in the center of seated participants around a table requires no effort, and many users find the meeting more natural.

A recent study examining use of a CI in combination with a Comfort Digisystem conference microphone was conducted at the Institute of Physiology and Pathology of Hearing, Warsaw, and the Institute of Sensory Organs, Nadarzyn, in Poland.  The study was supported by Comfort Audio and conducted under the direction of Olszewski Å . Olszewski, A. Majchrzak and P.H. SkarżyÅ"ski. 

The objective of the study was to measure the effect on speech understanding of using a Comfort Digisystem conference microphone incorporating active Perceptual Speech Enhancement (PSE), in combination with cochlear implants.  PSE is a digital sound processing algorithm that enhances meaningful parts of speech and reduces noise.

In the study, 10 adults who used of cochlear implants were tested. The participants had a range of CI experience from 18 months to 7 years.

Participants were evaluated using the Matrix test in two conditions: using the CI alone, and using the CI in combination with a Comfort Digisystem conference microphone (model DC 20) and neck loop receiver.  The test was performed in an audiometric booth, with the signal coming from a loudspeaker placed 1 meter in front of the user or the conference microphone. The conference microphone was placed between the sound source and subject, as it would be during actual use.

The initial stage of the study was to determine the SNR for the each subject to understand 50% of the words using their CI alone. The results show that the ten CI-users differ considerably in the SNR they needed to meet the critical figure (Figure 1). The lower the SNR, the easier words were understood by the subject.

Figure 1.  SNR required for 50% intelligibility on Matrix test for each subject (n = 10) in the CI-only condition.

The test was repeated in the second condition (CI + Comfort Digisystem conference microphone and neck loop receiver).  Large individual differences were again noted (Figure 2).

Figure 2. SNR required for 50% intelligibility on Matrix test for each subject (n = 10) in two conditions: CI-only (blue) and CI + Comfort Audio DC 20 conference microphone with neck loop (red).

Six of the ten subjects had improved SNR Matrix intelligibility using the conference microphone DC 20. That is, they were able to achieve comparable levels of intelligibility (determined to be 50% for the purpose of testing) at lower SNRs.  The improvement range was 0.7 to 9.0 dB, an average of 4.24 dB. Four subjects did not improve their SNR Matrix intelligibility when using the conference microphone. Results are shown in Table 1, and the type of CI processor used by each participant is also noted.

Table 1. SNR improvement in dB for each subject in the CI + conference microphone condition over the CI-only condition.  The type of CI processor is also noted for each subject.

In answer to your question, yes, conference microphones may help people who use cochlear implants to understand speech although there is individual variability.  There are several possibilities for the variation in outcomes in this study.  The CI-processor could be a factor and suggests further investigation is necessary. Other factors may include familiarity with Comfort Audio Perceptional Speech Enhancement, indicating a period of adaptation may be required, and experience using a conference microphone.

For more information about the Comfort Audio DC 20 conference microphone, and other solutions from Comfort Audio, please visit https://www.comfortaudio.com/us/ or the Comfort Audio Expo Page on AudiologyOnline.

References

Van Hardeveld, R. (2012, November). Quality of life of adult CI-users. Presentation at Independent Information Centre on Cochlear Implants (ONICI) conference, Antwerp, Belgium.

Fu, Q.-J. & Nogaki, G. (2005). Noise susceptibility of cochlear implant users: The role of spectral resolution and smearing. Journal of the Association for Research in Otolaryngology, 6, 19-27.