Google Mail Notification Sound is an add-on for the Chrome browser that enhances the functionality of the Google Mail Checker extension. It plays a notification sound whenever new, unread emails are fetched, providing an audible alert to users. Additionally, it displays the number of unread email messages within the extension's icon, allowing users to easily see how many new emails they have without opening their inbox.

With Google Mail Notification Sound, users can stay updated on their email activity without constantly checking their inbox. The notification sound provides a convenient way to be alerted to new messages, even if the browser window is not in focus. The number badge on the extension's icon serves as a visual reminder of the unread emails, ensuring that important messages are not missed.

Overall, Google Mail Notification Sound is a useful add-on for Chrome users who want to enhance their email experience with audible notifications and a visible indicator of unread messages.