In the case of interviewing people who do not speak dominant languages (for Latin America, Spanish or Portuguese), or if the interviewee is bilingual but wants to pick up his second language (eg some non-dominant, official or non official, indigenous or minority language), it is necessary to have the assistance of an interpreter. Here it is necessary to emphasize a fundamental difference: the one who translates the spoken word, interprets; the one who does it in writing, translates.
It is advisable to record the interviews using the original language (or dialectal variety), as it expresses unique sounds and words, and ideas for which there is no direct translation. In this case, a simultaneous interpreter can be used (if the language is not understood) or a translator may be found, to perform his work at a later stage (the transcription).
When looking for people for this task, it should be considered an important fact: that a person is bilingual does not mean that s/he is a good interpreter. Many feel uncomfortable repeating what another person says. Others do not interpret everything the interviewee says. Others will answer the questions for themselves rather than ask them.
The interviewer should look for someone who is friendly, and not aggressive. In this sense, the community itself can advise. It is convenient to have more than one interpreter: times and translations / interpretations can be handled better. The more they know about the project, the more they can help. It should be explained to them how they should interpret (the whole sentence, at the end, during a pause...). The young interpreters of the community itself are not adequate: languages have degenerated over the years, and therefore the elders handle many more words and other speeches. It is preferable, therefore, an adult who is respected by his/her own people.