What makes a window quiet
Sealing: gaskets and the seal around the frame often matter more than the glass itself.
Glass: laminated or insulated glazing generally blocks more noise than a single pane.
Opening type: a closed casement usually seals better than a sliding window.
Advice
Tell the member firm where and when the noise comes from, ask for a suitable glass and window type, and get the glass make-up and thickness written into the quotation. Replacing external windows is usually minor works and must be done by a qualified contractor.
Official sources
This page is general guidance, not legal advice. If rules change, the government department's information prevails.