Analysis Of The Oldenburger Satztest

To optimally investigate the thesis hypothesis and normalize performance of NH and HI participants, on the first day of measurements the Oldenburger Satztest (OLSA) {Wagener:1998wh} was conducted to establish an individual speech-reception threshold (SRT) of each participant. The OLSA test is an adaptive speech-in-noise test, similarly to the procedure used by Mackersie and colleagues (2015). The OLSA matrix test, contains 120 sentences with a constant grammatical structure in the form "name verb numeral adjective object" (e.g., "Peter has five red cars"). The sentences were presented to the participants inside a soundproof booth over inserted earphones (E-A-RTONE 3A). Participants listened to 20 sentences in each of the 3 consecutive sentence
For that, participants were required to wash their hair and were afterwards seated in a comfortable chair in a sound-attenuated room with a screen placed approximately 1m in front of them. An EEG cap was fitted on the participant using the regular EEG cap preparation procedures. Firstly, the participant's skin was prepared with an abrasive gel and alcohol, whereafter a mobile 24 channel EEG cap was put on the head. A little amount of electrolyte gel (Abralyt HiCl, Easycap GmbH, Germany) was inserted into the silver chloride (Ag/AgCl) electrodes to reduce the contact impedance, which was maximally at 20 kΩ for the majority of the participants. One of the cap sensors (CPz) was extracted from its usual position on the cap and was instead attached on the participant's lower left back, with a purpose of recording ECG activity. It was attached by Leukosilk tape (Beiersdorf AG, Germany), supposing to prevent the electrode from moving. All the sensors were connected to a wireless mobile 24-channel direct current EEG amplifier (SMARTING, mBrainTrain, Serbia) attached at the back of the head. EEG and ECG data were obtained with 24 bit resolution and 500 Hz sampling rate, against a reference (FCz) and a ground electrode (Fz) and wirelessly sent to a recording computer via Bluetooth connection. Additionally, participants were equipped with the eye-tracking glasses, measuring pupil diameter (SMI, Teltow, Germany) with a sampling rate of 30 Hz. Its signals were transmitted to the same recording computer as EEG and ECG measures through a wired connection. All three measurement methods plus the marker stream were, then, integrated utilizing the 'lab streaming layer' package, which unifies and time synchronizes incoming measures (see Fig.