How do I fix poor sound quality on my iPhone 16 Pro?

The speaker can have hardware issues, yes

1. Turn off Silent mode:

• If your device has a Ring/Silent switch, move the switch forwards – towards the device’s display – so the orange section isn’t showing. If you’re using an iPhone with an Action button or an iPad, you can also swipe down from the top right-hand corner to open Control Centre and make sure Silent mode is turned off. Find out how to access Control Centre on your iPhone or your iPad.
• 
  
  • 
    
  • If your iPhone has an Action button and it’s set to Silent mode, press it. You can also change the feature that the Action button controls.

1. Open Settings > Focus > Do Not Disturb and make sure Do Not Disturb is off.
2. Remove all screen protectors, films or cases from your device. 
3. Check the opening of the speaker to see if it’s blocked or dirty. On iPhone only, make sure the receiver isn’t blocked or dirty. 
4. If necessary, clean the speaker or receiver opening with a small, soft-bristled brush. Make sure the brush is clean and dry.
5. Go to Settings > Sounds (or Settings > Sounds & Haptics) and drag the Ringtone and Alerts slider back and forth a few times. If you don’t hear any sound, or if your speaker button on the Ringtone and Alerts slider is dimmed, your speaker may need a service.
6. If you can hear sound, try making a call with your iPhone and turn on speakerphone. On iPad or iPod touch, make a FaceTime call. If you still can’t hear anything, or you hear static or crackling, then your network or reception could be the issue. Try calling again later or from a different location.

Get service

If your device still has sound issues, you may need a service. Get a service.