## 3 Materials and Methods  
### Dataset  
This study was approved by the Kaunas Regional Ethics Committee for Biomedical Research (No. BE-2-49). Voice samples were obtained from 104 PD subjects examined in the Lithuanian University of Health Sciences (Lithuania). Serial numbers were assigned to each participant at the time of inclusion to protect their identity. Speech recordings of the phonetically balanced Lithuanian sentence \"Turejo senele zila ozeli\" (The grandmother had a little grey goat') were obtained using a T-series silent room for hearing testing (T-room, CA Tegner AB, Bromma, Sweden) via a D60S Dynamic Vocal (AKG Acoustics, Vienna, Austria) microphone placed 10.0 cm from the mouth with an about 90\({}^{\circ}\) microphone-to-mouth angle. Speech recordings were made at a rate of 44,100 samples per second and were exported as uncompressed 16-bit deep WAV audio files. The phonetically balanced Lithuanian sentence \"Turejo senele zila ozeli\" (The grandmother had a little grey goat') was recorded using a T-series silent room for hearing testing and a D60S Dynamic Vocal (AKG Acoustics, Vienna, Austria) microphone placed 10.0 cm from the mouth with an approximately 90\({}^{\circ}\) microphone-to-mouth angle. Speech was recorded at 44,100 samples per second and produced as uncompressed 16-bit deep WAV audio files. Speech samples were obtained from patients diagnosed with Parkinson's disease at the Lithuanian University of Health Sciences Hospital, Kaunas Clinics by an experienced neurologist according to the UK Parkinson's Disease Society Brain Bank criteria [75]. Only physically independent patients up to stage 3 on modified Hoehn and Yahr scale (H-Y), without any concomitant neurological or hearing disorders, respiratory tract infection, or any voice problems unrelated to PD at the time of the recording, were invited to participate in the study. The time of the recording was adjusted to best suit the schedule of the patient as well as the availability of the examiner, therefore, not all the recordings were made in best \"on\" state of the patients, who took medication for PD. The sample consisted of 61 patients (28 males and 33 females), aged 39-84 (mean age 64.9 (SD 9.7)), with a duration of the disease of up to 14 years (mean 3.6 (SD 3.6)), based on the time of diagnosis. Most participants were in H-Y stage 2 (29.5%), followed by H-Y stage 3 (26.2%), and H-Y stage 2.5 (19.5%). The normal speech subgroup was composed of 43 healthy volunteers who had no present or pre-existing speech, hearing, neurological, or laryngeal disorders and considered their speech as normal. Volunteers were free of upper respiratory infection at the time of the recording. Laryngeal endoscopy was done using the XION EndoSTROB DX device (XION GmbH, Berlin, Germany) with a 70-degree rigid endoscope without topical anesthesia for both the patient and control groups. Subjects with any pathological alterations of the laryngeal fold, such as polyps, granulomas, paralysis etc., were not included in the study. This dataset was used only for the validation of our U-lossian network. For the training of the algorithm we have used the publicly accessible ItalianPVS corpora [76], where each speaker recorded five sustained vowel sounds with two iterations each. These samples were contributed by 22 (10 men and 12 women) healthy volunteers (HC) aged 66-77 years and 28 (19 men and 9 women) patients with PD, aged 40-80 years. The healthy subgroup did not report particular speech or language disorders. The patients reported no speech or language disorders that were not related to their Parkinson's disease. All patients received antiparkinsonian treatment. The disease severity was classified by the specialists as <4 on the modified Hoehn and Yahr scale for 25 patients, stage 4 for 2 patients, and stage 5 for 1 patient. All of the speakers in this corpus were recorded in Bari, Puglia, Italy.