If your Windows computer is making notification sounds when sleeping, restart it and see if it helps. At times, the issue is nothing but a glitch that can be resolved by rebooting. In case the issue ...

Is the Outlook (new) app not sending notifications on your desktop? Several users have reported that they are not receiving notifications for new emails, despite having enabled notification settings.

After updating to iOS 15, a number of users have discovered that they are no longer hearing notification sounds for the Mail app. To fix this issue, you may need to adjust your Mail notification ...