In this verse, the heavens, as dwelling place of God, are called upon first, to praise the Lord.
After that, the call goes out to the heavens, such as we speak of when we, for example, say, The sun is high in the sky/heavens.
Then you may think of the firmament or of the clouds in the sky. We see a connection here with Psalm 19:1–5: The heavens declare the glory of God.
God also speaks
via creation, that is, created reality. Paul also points to this in Romans 1:20.
4 Praise him, you highest heavens, and you waters above the heavens!