No, a computer can not hear people as it's not a living thing (some living things can not hear). However, if you attach a set of head-phones to your computer than it can hear you.
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maybe because your listening to the news on your computer?
check your spekers or your computer.
Computer architecture is not useful for the people whose use the computer for general purposes. Mostly, computer architecture helps those people who are in the manufacturing/development sector.
that is called the moniter with speakers