I think the ability to make sound depends on both the strength of the stream and the architecture of the pussy, both of which vary with individuals. The same individual may hiss at times, for example when her need to pee is urgent, and pee completely silently, at other times. The sharpness of the hiss, whether it sounds like "ssssshhh" or "sssss" also seems to vary with individuals, due to pussy architecture and strength of stream, and even with the same individual, at different times. In some women, the sound is more high-pitched, and almost melodious, sometimes enhanced by a porcelain toilet