QuietWalk Sound Absorption and Vapor Barrier 33.34-ft x 3-mm Premium Felt Flooring Underlayment (100-sq ft /Roll) in the Flooring Underlayment department at Lowes.com
How to Soundproof Your Floors
STEICO 3 mm 1/8 Inch Wood Fiber Flooring Underlayment for Laminate Vinyl LVT LVP Hardwood Floor 90 SqFt Natural Sound Insulation Barrier - Amazon.com