The effect of the language proficiency of bilingual adults on the Canadian Digit Triplet Test

Background — Bilingualism or multilingualism is present in all parts of the world and the Canadian population is no exception to this situation, creating a need for effective clinical tools and guidance in the speech audiometry area. For example, the performance of bilingual or multilingual listeners on a speech test may be lower than the monolingual normative data because of their proficiency in the language of the test being used. It is then difficult to determine if the lower scores are related to the language competencies or indicative of a hearing deficit. The Digit Triplet Test (DTT) was first introduced in Dutch as an automatic self-screening test (Smits et al., 2004). Since then, it has been developed in many different languages. A Canadian English and French version of a digit triplet test (CDTT) has recently been developed (Ellaham et al., 2016) as a measure of speech understanding in noise. Normative data for monolingual adults have been collected for each version of the test. As there are some indications that closed-set speech tests, such as the CDTT, are more effective in evaluating basic speech recognition abilities in noise with bilingual populations than open-set tests, this study aimed at exploring the effect of the language proficiency of bilingual and multilingual adults on the Canadian Digit Triplet Test.

Methods — One hundred (120) adults with normal hearing thresholds were tested with both versions of the CDTT. A questionnaire about the linguistic experience was also completed by all the participants to determine the relative proficiency level in both languages, as well as the language dominance.

Results — Regardless of language proficiency levels, bilingual adults performed similarly on the Canadian English and Canadian French versions of the CDTT, and their performance is at par with that of monolingual individuals (based on previous findings).

Conclusions — Therefore, in a clinical setting, the CDTT can be carried out in the preferred language of the client.