The MacBook Pro's speakers are in a different league.
The 14-inch MacBook Pro has substantially better built-in speakers than the MacBook Air. It’s not close.
The Air’s speakers are fine for web calls and background music. They get loud enough and sound clear for what they are. But they’re thin. No bass. At higher volumes, they get strained and a bit tinny.
The Pro, on the other hand, has a bigger chassis and Apple’s best speaker system. It uses force-cancelling woofers that actually produce real bass. Dialogue in movies sounds full. Instruments have separation. You can watch a movie or listen to a podcast without reaching for headphones.
If audio matters even a little, the Pro is worth the upgrade.