How to mute or amplify wavesurfer 7 left or right channel?

Question

I spend lot of time to amplify channel audio or mute one channel left or right but no luck. some answer here Unable to mute one channel in wavesurfer.js

    function playLeft() {
        wavesurfer.backend.buffer.copyToChannel(left_zeros, 0);
        wavesurfer.backend.buffer.copyToChannel(right_data, 1);
    }

    function playRight() {
        wavesurfer.backend.buffer.copyToChannel(left_data, 0);
        wavesurfer.backend.buffer.copyToChannel(right_zeros, 1);
    }```

in wavesurfer 7 wavesurfer.backend.buffer is not prasent and 


wavesurfer.setFilters([splitter, leftGain, merger]);    wavesurfer.loadDecodedBuffer(buffer)

these funtions are not in current version wavesurfer 7.

How can i amplify or mute ony of channel?