If the application has no sound, there could be several reasons why this is happening. 

Android 

• To ensure that your device’s audio is working properly, it’s important to verify that your volume settings are correctly configured. Simply touch the volume buttons on your device to check that it’s not silent or in vibration mode. 
• Additionally, if your device has a “do not disturb” option, make sure it’s turned off in the settings section of your phone, as this can also limit the sounds of applications. It’s particularly important to pay attention to the settings for multimedia sounds, as these may require specific configurations.
• Be sure to review the audio settings based on the brand and model of your device to ensure the best possible audio experience.

iOS

• When accessing the app, please be sure to turn the Ring/Silent switch to ring

iOS 15 and later

• Access the Control Center by swiping downward from the upper-right corner of the Home or Lock screen.
• For the iPhone with Touch ID, access the Control Center by touching the bottom of any screen then dragging upward.

• Tap Focus
• The Control Center screen may vary slightly depending on the device model

• Tap Do Not Disturb to turn on or off.
• Do Not Disturb is on when the icon is highlighted.