Establishing a sound connection with insufficient people....

tim.rose2

Active member
As the title says really.  Anyone got any tried and tested methods of testing for sound connections between caves when you've insufficient people to have somebody each side?  I'm thinking along the lines of...
1. Enter cave 1, leave device making noise and exit cave.
2. Enter cave 2 and see if you can hear it.

The 'device' will need to be loud (i.e. equivalent of someone shouting) and be able to make said noise for a couple of hours to give time to get between the locations.  It will need to be cave proof (but not waterproof) and not matter if I leave it for a week or two should I not bother to go back into cave 1 on the same day to retrieve it.  A bonus would be if the device also emitted light, though obviously leaving a torch shining is the obvious solution to this.  Ideally something dirt cheap.

All ideas welcome though I'm particularly interested to hear from anyone who's had success doing this sort of thing.

Cheers in advance.
Tim
 

Fishes

New member
I've seen this kind of thing used in the past.

https://portek.co.uk/portfolio/double-bang-banger-ropes/

They can make quite a bit of smoke though and probably aren't bat friendly.
 

Bob Mehew

Well-known member
I would recommend snow avalanche transmitter & receiver, although the signal is radio rather than sound.  We managed to get proof of limited distance even though there was only solid rock between us.  And they kept going for days.  Otherwise possibly a rape alarm.  But you will have to mod it to put in a bigger battery to get the life time you want.  (That should not be to difficult and at ?10 for one it should be worth a punt.)
 

pwhole

Well-known member
I would hazard a guess that whatever you use to transmit will need to be low-frequency to have a chance of traveling through the rock - you may end up feeling it rather than hearing it, but that's fine. I've heard Hope Cement Quarry letting off a blast a few times inside Peak Cavern now, but I never heard the warning siren five minutes before!

If it wasn't for the possibility of leaving it in for a week, I'd suggest a boom-box playing drum n'bass. Alternatively, still leave a boom-box playing drum n'bass in, but also include some well-fed hippy dude and a UV light and tell him to keep changing the batteries until you return the next weekend ;)
 

ChrisJC

Well-known member
A piezo sounder / buzzer, at about 2kHz (where human hearing is at its most sensitive). They take very little power, so a decent lead acid battery and it would  last for ages.

Chris.
 

tim.rose2

Active member
There's two places I'd like to do this.  Both are likely to be 'open' passage through too tight rift so I don't think (hope) it'll need to penetrate solid rock.  Could be a few meters though.  When we tested Rumble to Grove Cliff Fissure it was around 20 m with some height variation involved and that was the limit of being able to shout at each other.  I'd hope both of these are less than 10 m and possibly only a couple so it might turn out loud is not required.

My first thought was some of Phil Collins finest work, a very cheap MP3 player and speaker but that won't be very loud. 

The piezo sounder idea looks perfect.  I know bugger all about electronics something like this + a 9 volt battery?
https://www.ebay.co.uk/itm/Piezo-Buzzer-Sounder-3-12V-DC-85Db-BUY-TWO-GET-A-THIRD-FREE/122923029230?hash=item1c9ec892ee:g:3IIAAOSw42JZI-~~

Would that work?  How long would it last?
 

ChrisJC

Well-known member
I was thinking something like this:
https://uk.rs-online.com/web/p/piezo-buzzer-components/1367925/
and a 12V battery like this:
https://ebay.us/hbxVni

The buzzer takes 50mA, and the battery is 7Ah, so that would last for about 140 hours. Enough time to place it, exit, pop into the Hunters for a beer, then go somewhere else and have a listen.

Chris.

 

tim.rose2

Active member
Thanks Chris looks like a great idea.  As a really cheap and smaller option would this work?
https://www.amazon.co.uk/WMYCONGCONG-Electronic-Sounder-Continuous-Connector/dp/B07J6Q6QMT/ref=sr_1_4?crid=39P4UKIZCD9KL&dchild=1&keywords=piezo+buzzer&qid=1617137148&sprefix=piezo+bu%2Caps%2C171&sr=8-4
Plus a 9v battery?
Looks like a 9v battery is 500 mAh so at 15mA should last 30 hrs.  Would only need a couple of hours.

 

mrodoc

Well-known member
The avalanche radio concept as Bob suggests seems to work and has been used successfully in Scotland on a link dig/
 

ChrisJC

Well-known member
tim.rose2 said:
Thanks Chris looks like a great idea.  As a really cheap and smaller option would this work?
https://www.amazon.co.uk/WMYCONGCONG-Electronic-Sounder-Continuous-Connector/dp/B07J6Q6QMT/ref=sr_1_4?crid=39P4UKIZCD9KL&dchild=1&keywords=piezo+buzzer&qid=1617137148&sprefix=piezo+bu%2Caps%2C171&sr=8-4
Plus a 9v battery?
Looks like a 9v battery is 500 mAh so at 15mA should last 30 hrs.  Would only need a couple of hours.

That would work. It would be quieter - I guess you could built it and see if you think it's loud enough.
In fact, those ones will also work at 12V for more loudness if 9V is not enough.

Chris.
 

tim.rose2

Active member
They can be when the caves are as shit excellent as those on Portland.  Been trying to doing this since the Autumn.  A mixture of lockdowns, poor weather and inability to get the right people together has led me to explore alternatives.
 

Leclused

Active member
mrodoc said:
The avalanche radio concept as Bob suggests seems to work and has been used successfully in Scotland on a link dig/

We have been using avalanche beepers (arva's) with suc6 in several occasions. Also walkie- talkies can be used  in some cases they work really good.

We pinpointed this summer a point post S6 in the Rigotte Cave (France) where the divers found a spot only 4.9m beneath the surface :)

 

zzzzzzed

Member
A few more suggestions:

A smoke alarm with a battery that?s going flat will beep every few minutes for several days.

You could also leave a fully charged head torch pointing down the rift.

If you are convinced it is a short distance you could push some drain rods through and leave them in place (with a reflective strip on the end because the connection may not be where you expect it to be).


Or, you could ask on this forum if anybody would like to help.
 
My first thought was some of Phil Collins finest work, a very cheap MP3 player and speaker but that won't be very loud. 


Doors ?break on through? on repeat?
 

Pitlamp

Well-known member
A carbide powered repeating crow scarer?

(But any snoozing bats wouldn't appreciate it, at this time of year, of course.)
 

Pitlamp

Well-known member
Or . . . would it be simpler just to advertise on here for someone with good hearing to visit the destination cave whilst you initiate the sound at the source cave? (This forum works really well for this sort of thing, as with many other thhngs.)

Or - isn't there some way of data logging sound levels? That would record the timing of any pulses of sound released, giving absolute confirmation of any connection.
 

Leo

New member
Pitlamp, your idea on recording the sound levels is surely the way to go. That way you can be the one making the noise! I use digital sound recorders often which would pick up anything you can hear with your own ears. Even the microphones on a modern iPhone can record deep sounds around 100 Hz, although not with great sensitivity.
 

tim.rose2

Active member
The sound recorder idea is a brilliant one.  I've everything needed to give that ago when the need arises again.

We actually used the piezo buzzer / 9v battery idea.  Unfortunately we didn't get a sound connection in either location I'd started this thread about but have since tried it again elsewhere and did.  Much of our problems getting enough people related the lockdowns - pleased to say we're regularly getting 4 + people on digging trips again now and with out a doubt people both sides is definitely the best option.



 

TheBitterEnd

Well-known member
tim.rose2 said:
Thanks Chris looks like a great idea.  As a really cheap and smaller option would this work?
https://www.amazon.co.uk/WMYCONGCONG-Electronic-Sounder-Continuous-Connector/dp/B07J6Q6QMT/ref=sr_1_4?crid=39P4UKIZCD9KL&dchild=1&keywords=piezo+buzzer&qid=1617137148&sprefix=piezo+bu%2Caps%2C171&sr=8-4
Plus a 9v battery?
Looks like a 9v battery is 500 mAh so at 15mA should last 30 hrs.  Would only need a couple of hours.

As a battery discharges the voltage drops so it would get quieter over time, also with most battery types you cannot discharge its full nominal capacity so you will probably get 10h or less of useful output but that sounds (  ;)  ) like more than enough for what you need
 
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