HEARING WHITE NOISE? Since September 2018, the Chrome browser occasionally starts to play white noise on WebSDR sites.
As a workaround, muting and unmuting usually restores normal audio.
Chromium engineers are looking into the problem.
Alternatively, use a different browser, like Firefox.
NO AUDIO? If you use Chrome and have no audio,
the workaround is to switch off Chrome's new autoplay policy, by typing chrome://flags/#autoplay-policy
in the navigation bar and changing this setting from "Default" to "No user gesture is required"
(and restarting the browser).