I have these wireless headphones from Sony which worked flawlessly until recently. Now, when they turn on, intermittent hissing is heard, combined with a very short hiss every two seconds. This happens regardless of the position from the transmitter.
To be on the safe side, I took mu headset to my sister's as she too has the same model of headphones and the hiss is not heard when connected to her base/transmitter. So it must be my transmitter that is sending this hiss sound. Also, when I turn the transmitter off, I can turn the headphones Tune knob and pick some local radio stations which sound normal and without hiss. So the headset seems to work fine and must be receiving the hiss from the transmitter.
I didn't find the right solution from the Internet