Fig. 4

Experimental procedure. Acoustic therapies were monitored for eight weeks, along with four follow-ups. THI and HADS questionnaires were completed in S2, S3 and S4. EEG signals at resting state (baseline) for six minutes were recorded in S1 and S4. In addition, three minutes of EEG recording was undertaken in S4 when participants were listening to their corresponding acoustic therapy. PM for 2.5 minutes was recorded in all of the four sessions, and AM was recorded from S2 to S4.