You have to click on the "Click To Get Voice Notifications" button once,everytime you open the page.
You will receive a sound after clicking as confirmation.
After clicking, you will receive voice notifications saying, Posted a new call,please refresh
Note 1: If you do not receive notifications,just use CTRL+SHIFT+R and then click on the "Click To Get Voice Notifications" again once.
Note 2 : Its works only when you are online on the intraday page. It does not work when browser is offline.