Probably yes, in the end up to the DM
The full quote for what is crossing the entrance is:
Spells cannot be cast across the extradimensional interface, nor can area effects cross it. Those in the extradimensional space can see out of it as if a 3-foot by 5-foot window were centered on the rope. The window is present on the Material Plane, but it’s invisible, and even creatures that can see the window can’t see through it.
So the only thing explicitly excluded from passing in or out are spells and area effects. However, if it behaved just like a normal opening in all other ways, then it would have been sufficient to just state the dimensions. As the spell does not say if it block sound or not, in the end the DM will have to decide so.
In our case, we play it to allow sound, and that has not caused issues. The main point I think for not allowing sound is that it becomes harder to co-ordinate actions between party members on the inside and on the outside. For example, a spotter outside you cannot just shout when the right time has come for the rest of the party to spill out and ambush a foe -- that spotter then would have to be visible from the entrance, and give some visual sign. It may also have some advantages, for example you can cast spells inside, without some enemies outside hearing you and possibly detecting your hideout.