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:As Caldwell and Nittrouer (2013) note, voicing contrasts for consonants may be relatively more resistant to hearing loss than other phonemic distinctions, a fact that has likely contributed to the results we found regarding how well bilingual children with CIs were able to match their peers’ productions when it came to initial stop voicing.
Category: