Help!! I have lived in my home for 10 years. All of a sudden , when I flush my toilet (guest bathroom) I can hear the water echo in the tub (in the same room) I figured that I don't use the bathtub that much so I ran the water in case there wasn't enough in the trap.
I flushed the toilet again after that & I didn't hear the echo of the water, but a day later when I flushed the toilet I heard the water echo in my tub again. Do I have a leaky trap or is it something else? HELP what to do... Never had this before in any of my other homes... I did have this problem in the master bath a few years ago. I flushed the toilet and heard water echo in my tub. I don't use it since I have a separate shower so I ran water like I did in the guest bath.. I have NOT heard that noise since.. So what's up with the guest bathroom?? Why do I still hear water echoing in the tub area when I flush my toilet?? I really don't want to have to break up my floor if I don't have to. My house is on a slab unfortunately...

Your trap may be leaking or you could have a blocked vent that cases the trap to be siphoned. Do you have an access panel to reach the supply and drain pipes to the tub?

No I have nowhere to get to anything... Is this something I need to worry about??
The tub is only used when we have guests, which maybe 1 - 2 times a year. For a week
At each stay... Would I have to break up the floor or the wall behind the tub to find this out?

If the trap is leaking water will be dripping onto something like a sub floor or into you foundation. It would only be about 2 cups so no huge damage. Usually you will get sewer gas if the trap is dry. Try this for a possible cure since you do not use this room often, pour 2 cups of corn oil down into the tub drain. The oil will not evaporate and is more difficult to siphon. After a week or so flush the toilet and tell us how its going.

Thank you for your help I will try your suggestion. Was I right though about the water echoing in the tub area. That it's the trap? Could it be something else?

The echo is caused by the trap being empty of water, the sound of your toilet water going down the drain could be heard in the absence of trap water, so yes you were 100% correct.