How sound travels underground

[mrodoc]

Another query. Some of you may have been reading the QWUH reports by the OR. Currently we have two dig locations. One is a dig downwards in a faulted boulder filled rift and some distance away round several corners and vertically above is another in a loose boulder strewn unstable bedding (theme developing there eh?). Last week somebody in he top dig reported hearing people mumbling in the lower dig and a bat has flown into it a couple of times. Now, I think that suggests there must exist a clear airspace for much of the distance between the two locations and it is not the route we take that goes round several awkward corners often in low crawling passage and upslope as well. What do others think? I think there must be a chamber or largeish passage existing between the two locations for sound to carry.

 

[Cantclimbtom]

Wouldn't a bat indicate clear airspace exists for all of the route (assuming of course it hadn't followed your crawl?)

Could this be answered by 2 or 3 people. One in the bottom chamber loudly mumbling (or some other sound generation method but a person is better as they can make loud sounds and quieter ones as needed), a person listening for the sound in the top chamber and someone halfway on the crawl route.
If the half way person hears nothing but the top chamber listener can hear the bottom chamber then that would prove a connection that isn't your crawl way?

 

[Cantclimbtom]

Or pipe tobacco (or similar ) smoked in the lower chamber

 

[mrodoc]

Another query. Some of you may have been reading the QWUH reports by the OR. Currently we have two dig locations. One is a dig downwards in a faulted boulder filled rift and some distance away round several corners and vertically above is another in a loose boulder strewn unstable bedding (theme developing there eh?). Last week somebody in he top dig reported hearing people mumbling in the lower dig and a bat has flown into it a couple of times. Now, I think that suggests there must exist a clear airspace for much of the distance between the two locations and it is not the route we take that goes round several awkward corners often in low crawling passage and upslope as well. What do others think? I think there must be a chamber or largeish passage existing between the two locations for sound to carry.

That is what I was thinking of doing next time.

 

[mrodoc]

The bat issue is interesting as it has relevance to another cave. When we entered the Frozen Deep we noticed how draughty it was and also piles of bat guano at certain points in the chamber plus bat remains in the same areas. The chamber is 100m vertically from the surface and only one entrance is known and to get from there to the Frozen Deep involved the opening of a number of solid chokes. I have been glibly told that bats can crawl through tiny spaces but I cannot see them crawling more than a few metres and they need a reasonable space to fly in. I have always assumed there is more passage to be found in Reservoir Hole if we dug at the right point. Perhaps we need to attach a very fine thread to a bat's leg and then follow that! To back up my views about how far bats can crawl I found this reliable information:"
. In adapting to hang by their feet horseshoe bats, unlike other bat species,have lost the ability to crawl well. This means that horseshoe bats need to fly into their roosts, " Also: "They need access points of 30cm (width) x 20cm (height) for lesser horseshoes and 40cm (width) x 30cm (height) for greater horseshoes.

 

[The Old Ruminator]

To help out. Here is the plan. The sound travels by one of the yellow routes. Top though areas yet to be found or bottom the long way around through the open route.