I installed enginered hardwood on a slab and do not have the hollow sound at all. Mine is glued down w/ Bostics best 100% urethane glue. Your slab needs to be nearly flat, and if not...a floor leveler used to make it nearly flat. I used weights (sand bags) on the planks to insure a good bond to the slab during the installation. Its all in the installation!!!.. I have seen many floating floors and do know the feeling/sound you describe.. I have also seen it on glued down floors where the floor was not level and the glue and plank seperated leaving that area of the floor with the hollow sound.. good luck with the new house

you can use different underlayments that may muffle the hollow echo standard floating floor systems with foam underlayments have.

Cork Underlayment may give a slghtly more solid sound, but they are a higher cost than the foams.

The best in my opinion is the fiber Floor Muffler Underlayment, which may give a significant improvement to the hollow echo, but its also way up there in terms of cost. Other benefits include:

• Reduces both reflective sound noise and through the floor sound transmission
• Designed to provide a sound similar to that of traditional wood floors
• Suitable for use over both concrete and wood subfloors
• Exceeds recommended moisture permeability ratings for installation over concrete slabs
• Optimal thickness for both comfort and stability
• Helps to eliminate subfloor imperfections
• Mold and mildew resistant as well as non allergenic
• Adds R Value to help insulate floors
• Strong enough for the most demanding commercial installations

No floating floor underlayment will give you the solid sound and feel of a nailed or glued hardwood system, but on varying levels somewhere in between.

Those are marketing gimmicks if you ask me, from "real world" trials and tribulation, experiences.

The sound resonance and feel, will never come close to the solid feel of gluedown.

Use of those products does have an effect on sound and feel.

We use them all the time when customers are concerned about sound and echo.

They do work as intended.

If you had experience with use of those underlayments, you would realize this.

Yes, the underlayment does make a considerable difference. But this is really a whole process of using a good sturdy product, proper underlayment and the flattest substrate you can achieve. Flatness is taken for granted by many installers and DIYers. I spend more time and work prepping something than I do installing over it.

Amen, Jerry.

Too many installers simply never check for height tolerance when its required before isntalaltion of almost any flooring product.

It will certainly add to the hollow and echo.

Does the hollow sound mean that those areas are likely to cup, when the wood expands because those pieces are not down securely?

hollow sound and cupping are totally unrelated. Cupping is due to moisture. The hollow sound is because the floor is floating. Even with floating floors engineered generally 'sounds' better than with a plastic laminate.

Sorry, I was unclear. I meant the hollow sounds on a glue down installation. Are those areas likely to cup when the wood expands since it is not secured to the concrete?

not unless there is excessive moisture present to warp (cup) the wood.

a floating floor expands as a panel vs individual boards so there is no need for it to be secured to the floor.