Background: Guidelines established by the American Academy of Audiology (AAA) currently recommend behavioral testing when fitting frequency-modulated (FM) systems to individuals with cochlear implants (CIs). A protocol for completing electroacoustic measures on CI sound processors has not yet been established or validated when fitting either FM or digital-modulated (DM) systems, mini microphones, or mini microphones coupled to DM systems. In response, professionals have used or altered the AAA (2008) electroacoustic verification steps for fitting FM systems to hearing aids when fitting FM/DM systems, mini microphones, or mini microphones coupled to FM/DM systems to CI sound processors. Purpose: The purpose of this research is to determine if the electroacoustic verification guidelines established by AAA (2008) for fitting FM systems to hearing aids are feasible and verifiable when fitting mini microphones and mini microphones coupled to DM systems to CI sound processors. Research Design: Electroacoustic measures were conducted on 51 Cochlear Nucleus 6/CP910 sound processors, one Cochlear Wireless Mini Microphone 2+ (MM2+), and one Phonak DM System (one Roger Inspiro transmitter and one Roger X receiver) using an adapted AAA (2008) protocol (Nair et al, 2017). Phonak?s recommended default receiver gain setting was used with the Roger X receiver and adjusted if necessary to achieve transparency. Transparency refers to when the signal output of the device is the same when coupled and when not coupled to remote microphone technology. Study Sample: Electroacoustic measures were conducted on 51 Cochlear Nucleus 6/CP910 sound processors. In this study, the 51 Cochlear Nucleus 6/CP910 sound processors were either streaming to the Cochlear MM2+ or streaming to the MM2+ coupled to a Phonak DM system. Data Collection and Analysis: In a clinical setting, using the AAA (2008) protocol for electroacoustic measurements when fitting FM systems to hearing aids, electroacoustic measurements using various equipment (MM2+ and Phonak DM system) were performed on 51 Cochlear Nucleus 6/CP910 sound processors using the Audioscan Verifit to determine transparency and verify DM advantage, comparing speech inputs (65 dB SPL) in an effort to achieve equal outputs. If transparency was not achieved when the CI sound processor was streaming to the MM2+ coupled to the Phonak DM system at the default receiver gain, adjustments were made to the Roger X receiver?s gain. The integrity of the signal was monitored with the manufacturer?s monitor earphones. Results: Using the AAA (2008) hearing aid protocol, when the Cochlear Nucleus 6/CP910 sound processor was streaming to the Cochlear MM2+, transparency was achieved for 50 of 51 CI sound processors. Again, using the AAA (2008) protocol when the Cochlear Nucleus 6/CP910 sound processor was streaming to the Cochlear MM2+ coupled to the Phonak DM system at Phonak?s recommended default receiver gain, 28 sound processors achieved transparency. After the receiver gain was adjusted, the...

Both protocols were shown to be effective in taking reliable electroacoustic measurements and demonstrate transparency. Both protocols are felt to be clinically feasible and to address the needs of populations that are unable to reliably report regarding the integrity of their personal DM systems.

Forty-six subjects with normal hearing, mean age 20.2 years, were selected from 451 volunteers completing a questionnaire concerning hearing, exposure to noise, experiencing TTS-like symptoms, and speech understanding. Metrics quantifying reports of TTS-like symptoms were constructed from responses to questions concerning hearing immediately after noise exposure. Statistically significant deteriorations in scores on the Speech, Spatial and Qualities of Hearing Scale (SSQ) (Gatehouse & Noble, Int J Audiol 43, 85-99 (2004)) were found with increasing values of TTS metrics for all SSQ questions. Groups reporting TTS-like symptoms (“exposed”), and “controls” (with little / no noise exposure and no reports of TTS-like symptoms), were formed from the subject pool with mean hearing levels differing <2 dB from 250Hz—8kHz. There was no difference in mean word scores between groups in a Modified Rhyme test conducted in speech-spectrum shaped noise. However, the exposed group exhibited a statistically significant deterioration in threshold for detecting 4Hz amplitude modulation of a 500Hz carrier at 10 dB sensation level (SL) compared to controls, and an improvement at 50 dB SL. It thus appears that TTS-like symptoms reported by persons with normal hearing may be associated with subtle suprathreshold changes in auditory performance. [Work supported by NIOSH.]