Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Instruments to evaluate the impact of hearing loss on QoL Assessment of QoL deterioration due to hearing loss can be achieved through several instruments, as reported in different studies in the literature.(8,9) These can be divided into hearing-related QoL instruments (Table 1) and generic QoL instruments.
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