Determining fitting ranges of various bone conduction hearing aids.

OBJECTIVES: To define fitting ranges for nine bone conduction devices (BCDs) over different frequencies based on the device's maximum power output (MPO) and to validate the assessment of MPO of BCDs in the ear canal. BACKGROUND: Maximum power output (MPO) is an important characteristic when fitting BCDs. It is the highest output level a device can deliver and is one of the major determinants of a device's fitting range. A skull simulator can be used to verify MPO of percutaneous BCDs. No such simulator is available for active and passive transcutaneous devices. DESIGN: The MPO of nine different BCDs was assessed either by real-ear measurements and/or with skull simulator measurements. MAIN OUTCOME MEASURES: MPO and cross-validation of the methods using the Bland-Altman method. RESULTS: Percutaneous BCDs have higher MPO levels compared to active and passive transcutaneous devices. This results in a wide dynamic range of hearing for percutaneous devices. Moreover, the assessment of MPO by real-ear measurements was validated. CONCLUSION: Based on MPO data, fitting ranges were defined for nine BCDs over seven frequencies.

Benefit of contralateral routing of signals for unilateral cochlear implant users.

One way to improve speech understanding in noise for HI with a unilateral hearing loss is by contralateral routing of signals (CROS). Such a CROS-system captures sounds with an additional microphone at the worst hearing ear and transmits these to the better one. The better ear is then provided with a mix of signals originating from both ears. The goal of this study is to quantify the effect of a CROS-system on speech reception thresholds (SRTs) with unilaterally implanted CI-users in diffuse and directional noise as a function of speaker location. Listening tests are performed and an accurate directional intelligibly model is proposed used for further analysis. In diffuse noise it is concluded that the use of a CROS system results in a maximum gain in SRT of 7.9 dB when speech comes from the CROS side compared to a maximum loss in SRT of 2.1 dB when speech comes from the implanted side. In the case of directional noise, the effect of the CROS is symmetric and the maximum loss or gain in SRT was around 9 dB. The study therefore shows a clear potential of using the CROS system in diffuse noise.