Hi, I'm not convinced that laying MDF would be a solution, this could be a lot of work in cutting and trimming and presumebly, you would still be laying carpet with and underlay on this, furthing increasing the cost with no guraentee of reducing the noise signaficantly.
I would opt for a dense crumb underlay which will provide good impact and airbourne sound absorbsion. Try looking at the soundproofing projects on the website.
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