*2.4. Data Extraction*

All study characteristics and outcomes were extracted by S.A.I. and P.R. independently. The primary outcome was the difference between pre- and post-operative evaluation of tinnitus on validated multi-item tinnitus distress questionnaires and/or objective evaluation measurements. Additional outcomes were also extracted including hyperacusis, sound hypersensitivity, speech perception, sound localisation, word recognition, quality of life, work performance, and psychosocial comorbidities.

#### **3. Results**

#### *3.1. Search Strategy and Study Selection*

A total of 474 records were retrieved, and 31 studies were included in the systematic review (Figure 1). Post-implantation tinnitus suppression was analysed in 479 patients using various assessment methods. These studies were divided into two groups; 14 studies in which the primary complaint was tinnitus, and 17 studies in which tinnitus was not the primary complaint. Some studies had an overlap in their population samples [54–57].

**Figure 1.** PRISMA 2020 flow chart diagram for updated systematic reviews which included searches of databases and study selection. Last date of search is December 2021. From: Page M J, et al. [52]. *\* not relevant to the topic, \*\* Full text not found*.
