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Acoustic hearing can be preserved after cochlear implant (CI) surgery, allowing for combined electric-acoustic stimulation (EAS) and superior speech understanding compared to electric-only hearing. Among patients who initially retain useful acoustic hearing, 30–40 % experience a delayed hearing loss that occurs 3 or more months after CI activation. Increases in electrode impedances have been associated with delayed loss of residual acoustic hearing, suggesting a possible role of intracochlear inflammation/fibrosis as reported by Scheperle et al. (Hear Res 350:45–57, 2017) and Shaul et al. (Otol Neurotol 40(5):e518–e526, 2019). These studies measured only total impedance. Total impedance consists of a composite of access resistance, which reflects resistance of the intracochlear environment, and polarization impedance, which reflects resistive and capacitive properties of the electrode–electrolyte interface as described by Dymond (IEEE Trans Biomed Eng 23(4):274–280, 1976) and Tykocinski et al. (Otol Neurotol 26(5):948–956, 2005). To explore the role of access and polarization impedance components in loss of residual acoustic hearing, these measures were collected from Nucleus EAS CI users with stable acoustic hearing and subsequent precipitous loss of hearing. For the hearing loss group, total impedance and access resistance increased over time while polarization impedance remained stable. For the stable hearing group, total impedance and access resistance were stable while polarization impedance declined. Increased access resistance rather than polarization impedance appears to drive the increase in total impedances seen with loss of hearing. Moreover, access resistance has been correlated with intracochlear fibrosis/inflammation in animal studies as observed by Xu et al. (Hear Res 105(1–2):1–29, 1997) and Tykocinski et al. (Hear Res 159(1–2):53–68, 2001). These findings thus support intracochlear inflammation as one contributor to loss of acoustic hearing in our EAS CI population. [ABSTRACT FROM AUTHOR]

Objective: Hearing aid technology can allow users to "geo-tag" hearing aid preferences using the Global Positioning System (GPS). This technology assumes that listening environment characteristics that affect hearing aid benefit change little in a location over time. The purpose of this study was to investigate whether certain characteristics (reverberation, signal type, listening activity, noise location, noisiness, talker familiarity, talker location, and visual cues) changed in a location over time. Design: Participants completed GPS-tagged surveys on smartphones to report on characteristics of their listening environments. Coordinates were used to create indices that described how much listening environment characteristics changed in a location over time. Indices computed in one location were compared to indices computed across all locations for each participant. Study sample: 54 adults with hearing loss participated in this study (26 males and 38 females; 30 experienced hearing aid users and 24 new users). Results: A location dependency was observed for all characteristics. Characteristics were significantly different from one another in their stability over time. Conclusions: Listening environment characteristics changed less over time in a given location than in participants' lives generally. The effectiveness of GPS-dependent hearing aid settings likely depends on the accuracy and location definition of the GPS feature. [ABSTRACT FROM AUTHOR]