Non-PRO Chinese to English Science Education / Pedagogy Grammatical Analysis

Sentence: 他定計劃的時候，老喜歡對別人說：「請你們不要大聲說話好嗎？」

1st Attempt: When deciding a plan he enjoys telling others, "Is there some need to talk so loudly?"

Question: What is the meaning of 老 in this sentence. Is it an abbreviation for 老師, 老時, or something else altogether?

As always you are welcome to comment on other parts of the sentence, as well.

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