Why does Rambam mean when he said that G_d didn’t speak at Mt Sinai

In his book Guide to the perplexed Rambam says that G_d does not speak. Then why is it said that everyone heard G_d speak at Mt Sinai.

Did G_d really speak at Sinai ? Was his voice heard ? What was Rambam really trying to say ?

Thank You

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Edit – I meant —–> What* does Rambam mean in the title.