ORIGINAL ARTICLE
GAIN AND MAXIMUM OUTPUT OF IMPLANTABLE HEARING DEVICES IN PATIENTS WITH MODERATE TO SEVERE SENSORINEURAL HEARING LOSS
Joost W. Zwartenkot 1, 2  
,   Ad F. M. Snik 1, 2,   Martin Kompis 3,   Christof Stieger 3, 4
 
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1
Department of Otorhinolaryngology & Head and Neck Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
2
Centre for Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
3
Department of ENT, Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland
4
ARTORG Center for biomedical engineering research, University of Bern, Bern, Switzerland
CORRESPONDING AUTHOR
Joost W. Zwartenkot   

Joost W. Zwartenkot, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, e-mail: j.zwartenkot@kno.umcn.nl
Publication date: 2012-09-30
 
J Hear Sci 2012;2(3):35–40
 
KEYWORDS
ABSTRACT
Background:
To determine the dynamic range and the maximum output of three current middle ear implants and to discuss optimal candidacy for middle ear implantation.

Study Design:
Clinical study

Material and Methods:
Gain and output measurements were compared for three types of middle ear implants: the Otologics middle ear transducer (MET), the Vibrant Soundbridge (VSB), and the Direct Acoustic Cochlear Stimulator (DACS). The performance of these selected implants in users with severe, predominantly sensorineural, hearing loss (50–65 dB HL) was studied. Patients with chronic external otitis and sensorineural hearing loss used either a MET (n=9) or a VSB (n=9) implant. Patients with a predominantly sensorineural hearing loss after surgically treated otosclerosis used a DACS (n=4). Patients were selected from two different implant teams but evaluated with the same protocol. The relative gain at threshold level was determined, viz. the bone-conduction threshold minus the aided soundfield threshold, divided by the bone-conduction threshold. Input–output measurements were performed with the devices in linear amplification mode and with unlimited output. In this latter data set, the maximum output and the input dynamic range of the devices were determined.

Results:
The relative gain for each of the three implants was comparable; however, the values were slightly lower than the generally accepted target values. The input dynamic range of the devices varied, with the widest range for the DACS and Otologics devices.

Conclusion:
The results from this study indicate that the first generation DACS device is a good option for patients with moderate/severe sensorineural hearing loss and surgically treated otosclerosis who require a hearing implant.

 
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