Experiencing no sound for Android notifications, or encountering strange characters in those notifications, can be incredibly frustrating. Let's break down the common causes and solutions for both problems.

No Notification Sound

A silent phone can lead to missed important alerts. Here's a systematic approach to troubleshooting:

1. Volume Checks: The Obvious, but Essential

First, ensure the obvious: that your media volume isn't muted or set too low. Separate volume controls exist for media, ringtones, and notifications. Use the volume buttons on the side of your phone and check if the notification volume is up. Also, check the volume settings within the sound section of your phone's settings app.

2. Do Not Disturb (DND) Mode

Do Not Disturb silences all notifications by default. Access the quick settings panel (usually by swiping down from the top of the screen) and confirm that DND is turned off. If it's on, tap the DND icon to disable it. Also, check the DND settings for any scheduled rules that might be inadvertently silencing notifications at certain times.

3. Notification Settings (App-Specific)

Android allows granular control over notifications for individual apps. Go to Settings -> Apps & notifications (or Apps) -> Select the app experiencing issues -> Notifications. Ensure that "Show notifications" is enabled and that sound is enabled for the specific notification categories. Some apps have multiple notification channels (e.g., 'General,' 'Promotions,' 'Updates'), each with its own sound setting. Verify that a sound is selected for each relevant channel.

4. Default Notification Sound

Android has a default notification sound that might be set to "silent." Go to Settings -> Sound & vibration -> Default notification sound. Choose a sound from the list. Sometimes, simply changing the sound and then changing it back can resolve the issue.

5. System Updates

Bugs in the Android operating system can sometimes cause notification sound problems. Check for and install any available system updates. Updates often include bug fixes that address these issues.

6. Battery Optimization

Aggressive battery optimization can sometimes prevent apps from sending notifications on time, or at all, including the sound. Go to Settings -> Apps & notifications (or Apps) -> Select the app experiencing issues -> Battery -> Battery optimization. Select "Don't optimize" to prevent the system from restricting the app's background activity.

7. Custom ROMs or Modified Systems

If you are using a custom ROM or have modified your Android system, there might be compatibility issues or settings that are interfering with notification sounds. Consider consulting the ROM's documentation or community for solutions.

Strange Characters in Notifications

Seeing strange characters instead of legible text usually indicates an encoding issue. Here's how to tackle it:

1. App-Specific Encoding

This is often an issue specific to a particular app. If it's limited to one app, investigate its settings for language or encoding options. If such settings exist, try changing them.

2. System Language and Locale

Ensure your system language and locale settings are correct. Go to Settings -> System -> Languages & input -> Languages. Verify that your preferred language is set correctly. Incorrect locale settings can sometimes lead to encoding errors.

3. Update the App

Outdated apps might have encoding bugs. Check for and install any available updates for the affected app.

4. Reinstall the App

If updating doesn't work, try uninstalling and reinstalling the app. This will ensure you have a clean installation of the latest version.

5. Contact the App Developer

If the problem persists, contact the app developer and report the issue. They may be aware of the problem and working on a fix.