Sensory Neuroengineering

Tobias Reichenbach
Friedrich-Alexander-University (FAU) Erlangen-Nuremberg

EEG setup My group works on the biophysics of hearing and neuroscience, at the interface of science, technology and medicine.

We use ideas from theoretical physics, mathematics, and computer science in combination with ear and brain imaging to investigate principles of human auditory signal detection and processing. Together with clinical collaborators we also investigate auditory and language impairments.

We aim to apply our findings in novel bio-inspired technology as well as in novel technology diagnosing and rehabilitating hearing and communication impairments.

The group is part of the Department Artificial Intelligence in Biomedical Engineering at the Friedrich-Alexander-University (FAU) Erlangen-Nuremberg.


Drug transport in the cochlea through steady streaming

neurostimulation and speech

The mechanosensitive hair cells in the inner ear, or cochlea, are vulnerable to overstimulation, which can cause damage to the cells and sensorineural hearing loss. Pharmacological treatments to prevent hair cell damage or to restore the cells' function after impairment are currently being developed. However, transporting the drugs to the hair cells has remained a major problem because the function of the cells relies on the intact encasing in the hard temporal bone. Here we show that steady streaming, a physical phenomenon that accompanies propagating waves, can be employed to transprt drugs from an entry point near the middle ear to the hair cells inside the cochlea.

L. Sumner, J. Mestel, T. Reichenbach
Steady Streaming as a method for drug delivery to the inner ear,
Scientific Reports (2021) 11:57. [pdf]

Webpage on auditory illusions

neurostimulation and speech

Auditory illusions are fascinating for they show us how easy our sense of hearing can be deceived. As an example, a Shephard's tone sounds as if it consisted of a single frequency that was, eerily, constantly rising! With a group of students we have developed a webpage on auditory illusions. The webpage contains audio demonstrations of a variety of such illusions, explanation of their origin, as well as further background research. By understanding how our sense of hearing can go wrong, we can learn more about the way our ears and brains sense and perceive acoustic stimuli.

Enhancement of speech-in-noise comprehension through neurostimulation

neurostimulation and speech

Transcranial current stimulation can influence neuronal activity. As a striking example, current stimulation paired to a speech signal, with the current following the speech envelope, can influence the comprehension of speech in background noise. The speech envelope is thereby a slowly-varing signal with frequency contributions that lie mostly in the delta and in the theta frequency bands. Here we show that the modulation of speech comprehension results from the theta band, but not from the delta band. Moreover, we find that the theta-band stimulation without an additional phase shift improves the speech comprehension as compared to a sham stimulus.

M. Keshavarzi, M. Kegler, S. Kadir, T. Reichenbach,
Transcranial alternating current stimulation in the theta band but not in the delta band modulates the comprehension of naturalistic speech in noise,
Neuroimage (2020) 210:116557. [pdf]

Measuring speech comprehension from EEG recordings

comprehension decoding

If hearing aids could measure how well a wearer understands speech, they might be able to optimize and adapt their signal processing to enable the best user experience. Hearing aids can potentially measure brain responses to speech from electrodes, but how this can inform on speech comprehension has remained unclear. Here we report significant progress on this issue. By combining machine learing with an experimental paradigm that allows to disentable lower-level acoustic brain responses from neural correlates of the higher-level speech comprehension, we show that speech comprehension can be decoded from scalp recordings.

O. Etard and T. Reichenbach,
Neural speech tracking in the theta and in the delta frequency band differentially encode clarity and comprehension of speech in noise,
J. Neurosci. 39:5750 (2019). [pdf]

Decoding attention to speech from the brainstem response to speech

ear eeg

We are often faced with high noise levels: in a busy pub or restaurant, for instance, many conversations occur simultaneously. People with hearing impairment typically find it difficult to follow a particular conversation, even when they use hearing aids. Current aids do indeed amplify all the surrounding sounds, not only the target. If a hearing aid could know which speaker a user aims to listen to, it could amplify that voice in particular and reduce background noise. Here we show that a hearing aid can potentially gain knowedlege of a user's attentional focus from measuring the auditory brainstem response from surface electrodes. We show in particular that short recordings, down to a few seconds, and a few scalp electrodes suffice for a meaningful decoding of auditory attention.

O. Etard, M. Kegler, C. Braiman, A. E. Forte, T. Reichenbach,
Real-time decoding of selective attention from the human auditory brainstem response to continuous speech,
Neuroimage 200:1 (2019). [pdf] [bioRxiv]

Tobias Reichenbach joins eLife's Board of Reviewing Editors

I am excited to join the Board of Reviewing Editors of eLife. eLife is a non-profit journal that is led by scientist, and is committed to publishing life-science research of high quality and importance in an open-access manner. I look forward to working with the eLife team and the academic community to further the journal's mission of providing a publication platform that helps scientists to accelerate discovery.