Ah, "the right-click the number" part did it for me. I always had went about right till the properties tab. I never thought to right-click it. Thank you. :-) But I observe that lowering the decibel value is not very different from lowering the percentage. Both of them pare down the amplitude of the signal. And then I get a really low signal, which I have to amplify. But the hiss is completely gone, even in the amplified signal. So, thank you very much. :-)

Thank you. I don't see a Gain control in my Sound control panel applet against the properties of the microphone. Where should I be looking?