The effect of early bilingualism on auditory temporal processing ability using time-compressed Persian speech test

Bilingualism is an important phenomenon with different effects on each aspect of language processing. Auditory temporal processing is a major component of the auditory processing ability. Since bilingual and monolingual individual’s brain process are different, and no studies have yet been conducted on the effect of temporal processing on speech recognition performance of Azeri-Persian bilinguals, the purpose of the present study is the comparison of auditory temporal processing between Persian monolinguals and early Azeri-Persian bilinguals. In this cross-sectional study, the Persian version of time compressed speech test was performed with monosyllabic words in three compression rates of 0, 40 and 60 percent in the most comfortable level in each ear, separately. The subjects were 36 Persian monolinguals and 36 Azeri-Persian bilinguals aged from 18 to 30 and were analyzed based on languages’ compression rate and ear factors. The speech recognition scores (SRS) in both groups were decreased by increasing compression rate and a significant difference was shown between mean SRS of the two studied groups (p<0.0001). There was no significant difference between three compression rates by the ear (p>0.05). In compression rate of 40 percent, bilingual group had lower speech recognition ability in comparison with monolingual group. In addition, there was more significant difference when compression rate increases from 40 to 60 percent.