Subjective and Objective Performance With the SONNET2EAS

Candidacy criteria for cochlear implantation include adults with normal-to-moderate low-frequency hearing and severe-to-profound high-frequency sensorineural hearing loss. A cochlear implant system includes two parts: 1) the internal electrode array that is surgically implanted into the cochlea, and 2) the external audio processor that picks up the acoustic signal. The external audio processor sends the converted acoustic signal to the internal device, which is presented as electrical pulses via individual electrodes and interpreted by the brain as sound. When acoustic hearing in the implanted ear is preserved postoperatively, cochlear implant recipients are fit with an electric-acoustic stimulation (EAS) device. An EAS device combines acoustic and cochlear implant technology into a single device to provide acoustic amplification of the aidable low-frequency hearing region and electric stimulation of the mid-to-high frequency region. Cochlear implant recipients demonstrate a significant improvement when listening with EAS as compared to listening with acoustic or electric stimulation alone on measures of speech understanding and subjective benefit. The benefit is thought to be due to the addition of acoustic low-frequency cues. The MED-EL SONNETEAS system was approved for commercial use in 2017 for adults (MED-EL, Innsbruck, Austria). Recently, the SONNET2EAS was approved and is currently MED-EL Corporation's newest EAS audio processor. While processing with the SONNET2EAS is currently the similar to that of the SONNETEAS, updated "front-end features", including improved artificial intelligence, are available within the device but have not been approved for commercial use. Front-end processing occurs in the external audio processor prior to the coding of the signal. This processing is intended to optimize signal perception in variable environments (e.g. complex, noisy listening conditions). Currently, the SONNETEAS and SONNET2EAS have two microphones receiving the incoming signal, which are then manipulated to allow for wind noise reduction (WNR) and directional processing. These features are included within the currently approved "Automatic Sound Management (ASM) 2.0" and primarily seek to improve speech perception in the presence of noise. ASM 3.0 may offer cochlear implant listeners an improvement in speech understanding, specifically in complex or noisy listening situations, and potentially improve ease of listening in a dynamic environment. Listeners of devices with front-end processing demonstrate similar or improved performance than with devices without this technology - dependent on the listening situation. The aim of the present investigation is to compare objective and subjective outcomes with the new front-end features to the current generation in EAS device users, using a within subject design.