No sound notifications are received on the website

Clear your browser's cache. How to do this using Chrome (Windows) as an example: 

1. go to Settings > Additional> Privacy and Security > Clear History;

2. select the required time range and tick the box next to "Images and other cached files";

3. or use the CTRL+SHIFT+DEL key combination.

In Google Chrome, there may be no audible notification when the page is refreshed until some action is perfomed on the page (e.g. a mouse click).

1. To understand that there is no sound due to browser limitations, you need to open the Developer“s Console and click the Console tab (F12 key).
2. The console will display the line «The AudioContext was not allowed to start. It must be resumed (or created) after a user gesture on the page. https://goo.gl/7K7WLu».

       It may be at the top of the page instead of  at the very bottom.

3. The sound notifications play differently for different users based on their browsing behaviour. This is a limitation of the browser itself, more details here: https://developer.chrome.com/blog/autoplay/#new-behaviors