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What’s the Difference Between ASL Interpreters and Certified Deaf Interpreters?

Deaf interpreter signing

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We all know American Sign Language (ASL) interpreters, but what are Certified Deaf Interpreters (CDIs) and how are they different?

Hearing vs. Deaf

The first major difference is that ASL interpreters are typically hearing individuals whereas CDIs are born deaf or hard of hearing. ASL interpreters must go through extensive training to become professional interpreters for the deaf community. CDIs on the other hand are already part of the deaf community and have a strong sense of deaf culture as a result of their upbringing.

Second Language vs. Native Language

For ASL interpreters, sign language is their second language. For CDIs, sign language is their native language. As is often the case for non-native speakers, working long hours in your second language can lead to mental and physical exhaustion, which can impact interpretation accuracy. CDIs are of course not affected by that additional cognitive strain.

Linguistic & Cultural Expertise

Because CDIs are native in sign language and deaf culture, they can communicate more easily and clearly with deaf individuals. CDIs specialize in the use of interpreting, gestures, miming, incorporating props, drawings, and other tools to provide detailed deaf communication. As ASL interpreters are focused on translating spoken language into sign language, their signing may not always be as accurate.

Interpretation Service

It should be clear by now that CDIs do not provide the same service as ASL interpreters. A CDI is an expert in signed language, but they obviously cannot interpret spoken language like ASL interpreters can. As a result, ASL interpreters and CDIs often work in tandem to produce more accurate interpretation. The ASL interpreter will interpret spoken language into ASL for the CDI, who then interprets it for the deaf individual. In turn, the deaf person will sign to the CDI, who interprets into ASL for the ASL interpreter, who then interprets it into the spoken language.


In a perfect world, a CDI should always be present to interpret for deaf individuals, especially in high-risk situations such as doctor’s appointments, court hearings, banking appointments, or when the deaf person is a minor or a senior citizen. Unlike ASL interpreters, however, there is a substantial shortage of CDIs because not enough deaf people are getting certified. Among thousands of deaf people, there may only be one or two CDIs. Many organizations are also hesitant to pay for both an ASL interpreter and a CDI, which does not help alleviate the shortage.

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