Sound Insulation: Underlay is highly effective at reducing both impact noise (the sound of footsteps) and airborne noise. This is particularly important for multi-story homes, apartments, and commercial buildings to minimize noise transfer between floors.
Comfort and Cushioning: A good underlay adds a soft, springy layer underfoot, making the floor more comfortable to walk on. This cushioning effect can be especially noticeable with hard flooring types like laminate and wood.