Hi shspainhour,
If you haven't done so yet, restart your iPhone. Although simple, this step can help correct some unexpected issues. It's also a good idea to make sure your iPhone is running the latest iOS version, since this can help with overall performance: Update your iPhone or iPad
If an update is available, be sure to create a backup before installing it.
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see more than one software update option available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
There are some additional steps that may be helpful here: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker
If the issue continues, you may want to consider getting them inspected at an Apple Store or Apple Authorized Service Provider. You can find stores here: Choose Your Country or Region
Or, if you'd prefer, you can reach out to Apple Support directly so they can look into this with you further. They can be contacted here: Get Support or by calling the most applicable phone number from this list: Contact Apple for support and service.
Regards.