Marlin Johansson

PhD student

About me

I am a PhD student in medicine, audiology, at the ENT-division at CLINTEC, Stockholm, with a background in clinical audiology. I have a special interest in hearing devices, psychoacoustics, newborn hearing-screening, neuroplasticity, children and unilateral sensorineural hearing loss.

Research description

The overall aim of my PhD project is to study the causes and mechanisms underlying congenital unilateral sensorineural hearing loss (uSNHL) and the effects of intervention.

In the first PhD publication (Ear & Hearing, 2020) we studied hearing aid outcomes in school-aged children with congenital uNSHL and demonstrate both hearing aid benefit and dis-benefit (n = 6). The statistically significant benefit was found in one-to-one communication, based on child and parent questionnaires. Hearing aid dis-benefit was found for sound localization measured with eye-tracking in sound field. Neither significant hearing aid benefit nor dis-benefit existed for speech understanding in background noise/speech (sound field and questionnaires) or reverberation (questionnaires). A close relationship between neural maturation and aided sound localization was also found, indicating that hearing aids may be more efficient if fitted earlier in development, before the brain adapts to asymmetrical hearing.

In the second PhD publication (Hearing Research, 2020) we studied heredity of transient evoked otoacoustic emissions (TEOAEs), that are recorded as part of the universal neonatal hearing-screening program. Before the study, one publication had estimated TEOAE heritability based on young adult twins’ TEOAEs. In a large consecutive sample of neonatal twins (n = 454), we found that the TEOAEs at birth are largely inherited, perhaps more than for young adult twins. Additionally, we found that sex and ear differences existed at birth, and that the twin testosterone transfer hypothesis, that female twins with male co-twins would have masculinized TEOAEs, was not supported for neonatal twins.

We are currently inviting all children with congenital uSNHL born in Region Stockholm to evaluate early hearing abilities, hearing loss progression, and the outcomes of very early hearing aid intervention longitudinally. Furthermore, we study the etiology as a factor in children with congenital uSNHL’s hearing development. The project will run over a few more years.

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