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I came to the US about a year ago. I changed my employer 3 months ago. The technical lead is American, and the 4 developers are Indian. They have all been with this employer for around 2 years, and hence, have a better understanding of the project and the work involved.
The other developers always speak in another Indian language which I do not understand, and thus, I cannot participate in their conversation. I speak Hindi (native language of India).
They always speak in English when the technical lead is around. I do not bother about their personal conversation, but they also do this for work-related conversations, which impacts my work.
I have tried having a good relationship with them, but I don't see it happening from their end. I work the whole day without talking to people, which is frustrating. I have never had this kind of work environment earlier, and have started talking to people from other teams.
I have requested them to talk in English once, but I can't keep reminding them about it all the time. Sometimes they say they are talking about something else. How am I supposed to know what they are talking about? I don't want to spoil team/work environment by asking them to talk in English every time or by complaining to the Manager.
Update: Regarding comments about forcing someone to use the language he/she is not fully comfortable in, note as I said, they all speak with the technical lead in english. we have team meetings/discussion where english is used. All the team members are comfortable in english.
Side note: Most of the I.T guys from India they all know english well, they have studied in english and successfully cleared the interview in english.