I have a male and is never heard him hiss! I've handled him a few times and he's never hissed, I bought him from someone as an adult and he was rarely handled so its not because of that.
They do hiss, but less often than most other hissers. I guess they're more tolerant of handling. Some others like G. oblongonota will hiss if I just look at them lol.
I've only heard my E. javanica males hiss so far. The females are always silent.
Mine are noisy little things! It's a very high pitch squeaky sound compared to the other hissers I have. It actually reminds me of the sound that little kittens make when they get startled and do that cute little spit-hiss. The Halloweens make me giggle sometimes when I'm in there cleaning and the whole tank suddenly erupts in little spits of noise. It's really comical.