Sudden burst from Headphones

[habb]

My 4 or 5 year old Sennheiser HDR120 wireless headphones have been very satisfactory but now they will suddenly send out a deafening burst of sound that is shocking and almost painful. This happens after about 2 minutes or so of a continuous quiet part of, say, a film. One answer to this is to turn the volume up and move the headphones away from the ears, which should not be unnecessary.
The tuning is ok and I have fitted new rechargeable batteries, so I suspect the transmitting system.
I am surprised at the price of replacements: do 'open' ones really leak much sound?
Are these present HDR120 ones 'open'?
Sennheiser again, for about £100?
Advice welcomed.

 

[fireberd]

I have those headphones. I bought them for use in my recording studio but they didn't work out. They are very susceptible to the least little movement away from the base transmitter. They have sat on a shelf "collecting dust" for at least 5 years.

I would suggest considering wired type headphones. Or if you must have wireless, consider Bluetooth types.