Hood and sounds

[Kin]

Recently i made an experiment with my wetsuit hood. I punctured small diameter 3mm holes just in the center of my ears so i can hear whats going on at the bottom. The cold water flowing made me dizzy so i pluged and glued the holes and tried something different. I punctured with a needle many smaller holes in all the ear lobe area. The cold water transfered more gradualy to the inside of the hood and also the equalization was alot easier but i didn't had any great sucess on hearing better underwater. In summer when diving without a wetsuit sometimes, i find very usefull the fact that i can hear very sharply and It helps me locate places where fish are feeding from the souds they make.
Any suggestions on a winter solution that will not ruin the wetsuit.

edit: already thought gluing a thiner piece of neoprene at those locations (tested it with a very thin hood) but still can't hear clearly.

 

[blaiz]

To be honest the only time I feel like I cant hear well is on the surface. Talking to my buddies can be difficult and hearing boats approaching is a little harder but on the bottom It seems to be loud and clear. Maybe our waters are just real noise.

 

[Lazuli]

I have heard some strange stuff underwater like crackling and popping sounds (not my ears popping!!). Odd sounds that seem to have no immediate explanation. I figure it is crabs or the beaks of Wrasse doing their thing. Once I was convinced I heard a dolphin or cetacean behind me, like a squeal or whine - really spooked me as I could see nothing around. Sometimes I get my hearing in U-Boat hydrophone mode and can make out someone hammering on a tanker parked offshore, or the faint thud of a diesel turning over. Part of me wonders whether the hood may enhance hearing underwater. Personally I've never noticed a problem except for equalising.

 

[blaiz]

Our waters hear are filled with noise. We have these little shrimp called snapping shrimp and you can hear them everywhere. Sounds like someone breaking a pencil. During whale season it is incredible how much noise there is. It seems the deeper you go, the louder it gets. Lately the singing has been so loud that you get this feeling like you swallowed someone's pager and its vibrating in your chest.

Plus, a lot of our fish species grunt and snap. Some fish you will hear before you will ever see them, and thats if you see them at all.

 

[Kin]

Right now due to cold weather and waters i can't try to dive without hood to test if there is any difference in sounds, but i remember that when i did it, there was a significant difference. Anyone that hunts in warm waters without hood but can try a hood also could post the relation.

edit:

It seems the deeper you go, the louder it gets.

I wonder if the reason for this is the compressing neoprene that becomes thiner alowing sounds to pass trough or the increased water pressure.

 

[Kin]

This site answered some of my questions.
http://library.thinkquest.org/28170/36.html
so without neoprene over your ears you can hear alot better just as in air.
I thing i will punchture the hood with two large holes, about 1.5cm and cover them with an insulating cloth with neoprene glue. That way will be thin and allow vibrations to pass trough. Also a i tried to compress a piece of neoprene so it gets thin but i couldn't make it more than 2mm. I guess the cloth with the glue on it will be thiner.

edit: My thought on "thinning" or completely removing the interior neoprene off the wetsuit leaving the outside lining soaked with neoprene glue making it water tight. Just want some opinions before i try.

 

[stuckinsurrey]

I have seen a lot of wetsuit hoods (separate to wetsuits) with perforated ear sections. I have always assumed that it is so that the water does not flush the hood through yet improving your ability to hear noise. There are lots on the surfing shop websites etc. The link below mentions better balance and noise transfer so I guess that could suggest that it would be easier to equalize. Looks just like a piece of neoprene with holes cut in it - so like what you were trying anyway! Good luck!

Stealth Hood - www.aldersportswear.com

 

[Erik]

You could keep the holes in the hood and use Doc's Proplugs, which eliminate water transfer against your eardrum.

 

[Kin]

Finaly i liked the idea of grinding and thining the neoprene at the ear spot, than making a hole to it. I used a dremel with a soft sandpaper like material to grind it down safely to the lining without eating it away completely
The result was not so good looking but it got thiner more smoothly than a simple hole. Will try the results tomorrow. Hope didn't ruin my hood.

 

[Drejcha]

I have heard some strange stuff underwater like crackling and popping sounds (not my ears popping!!). Odd sounds that seem to have no immediate explanation. I figure it is crabs or the beaks of Wrasse doing their thing. Once I was convinced I heard a dolphin or cetacean behind me, like a squeal or whine - really spooked me as I could see nothing around. Sometimes I get my hearing in U-Boat hydrophone mode and can make out someone hammering on a tanker parked offshore, or the faint thud of a diesel turning over. Part of me wonders whether the hood may enhance hearing underwater. Personally I've never noticed a problem except for equalising.

I don't think it was the hood, probably you just pased the termocline - the "big aerial":

...the thermocline is characterized by a negative sound speed gradient, making the thermocline important in submarine warfare, because it can reflect active sonar and other acoustic signals. Technically, this effect stems from a discontinuity in the acoustic impedance of water created by the sudden change in density.

At the beginning I borowed the suit with hood. It was too painfull for my ears - result was I bought one without hood. Otherwise I can't equalise. If I had the hood, my ears would be cut out

Maybe would be a nice solution if you glue a thin noncompressible membrane over the hole in the hood. I'm guessing, thin plastic like that stuff beach balls are made of or something like that.

The catch is, every material that is a good heat isolator is a good sound isolator too (usually). It's hard to have them both.

 

[Kin]

Tested it today and the results where good. Outside of the water on surface i can hear now crystal clear, including the superfast boats aproaching to my head. This is a very good safety measure as i would have killed mysef in the past if i hadn't opened my hood to listen a 12meter inflatable boat aproaching at 40 knots on me.
When i submerged my head under the surface i couldn't hear much probably because it was somewhat windy day and there was small waves that made interference with marine life sounds.
Thermal isolation on surface is perfect because the cavity is filled with air all time (probably the reason for poor hearing just under the surface). When diving deeper than 3m the air must somehow migrates from the neoprene cavity due to compression (feeling a slight cold sensation to ears).
I noticed that at that depth i could hear some of the cracking sounds that i only heard on summer wihout suit.
I wasn't sure if there was a sound improvement since i had a long time away from sea.
A second test i made was to wave the speargun right and left and guess what, i could hear it! A very low pitched sound but i could hear it.
Also the cavity empties itself from water when taking my head above the suface about ear level.
Didn't had the oportunity to dive deeper and make more tests because the water had realy poor viz today.
After all i got something extra for grinding away that small portion of neoprene from my suit.


Also found a speargun at the bottom and this!

 

[podge]

Nice one Kin, doesn’t look like that Bass heard you coming.

 

[Erik]

If you allow air to stay between the suit and your ears, you will damage yourself at deeper depths- something to consider. Initially easier equalising and you can hear better, but very bad consequences if you start pushing depths.
Cheers,
Erik

 

[jimy286]

Personally I would rather the warmth then extra sound.

If you go real real deep the narcosis allows you to hear what the fish are saying and talk back!

 

[Kin]

If you allow air to stay between the suit and your ears, you will damage yourself at deeper depths- something to consider. Initially easier equalising and you can hear better, but very bad consequences if you start pushing depths.
Cheers,
Erik

When diving deeper than 3m the air must somehow migrates from the neoprene cavity due to compression (feeling a slight cold sensation to ears).

The air does not stay there after the dive starts. Even the ear cavity keeps air inside but it fills slowly with water as long as you keep head underwater. The cold sensation to the ears is an indication that there is no air and the thin membrane contacts only with water inside. Being thin it is a bad insulator so the cold water takes up the heat from the water inside. If it was air then it wouldn't feel cold. At least thats what i think. Note that the suit is watertight, there are no holes, just thin walls.

 

[Erik]

If you use a suit with open rubber on the inside, the hood would usually seal around the ear and the air will compress as you dive. During shallow dives probably not a problem. But during deeper dives you would see or feel the suit pushing in against your head. Many divers actually cut the holes to make sure this doesn't happen on a deep dive. I have squeezed externally quite severely in the past, but I prefer to not have cold water pumping past my eardrum, so I have a regular sealed hood and make sure there is water between the hood and my eardrum when the day starts.

Eric Fattah also had a very bad squeeze due to this, and used to dive with small straws leading from outside the hood beside his face to the ear area underneath the hood.

 

[Kin]

Thanks for the info i will check that. The seal around the ear is something that never hapened to me but i heard some stories with barotraumas on the way back to surface (i thing you are referring to that right?).
I don't consider air in ear cavities durin dive a common thing, else everybody would have to fill the hood of the open cell suits with water before the dive.
Many times i weared my summer suit without filling the hood with water and dived pretty deep without feeling any air in my ears. So i belive the water atomaticaly displaces air in the suit. Some air traped in my back but as soon as i dived down the air left the suit.