That depends on how reverberant or "live" the room acoustics are, and how loud the background noise is. The PZM-11LL can pick up speech from 50 feet away outdoors on a quiet day. If the mic is indoors in a very echoey or reverberant room, and the background noise is high, you might be able to understand speech only if it is within 5 feet or so from the PZM-11LL. In a fairly quiet, dead room like a living room with carpet, the PZM-11LL should pick up intelligible speech from about 15 feet. The farther away the talker is from the mic, the more room acoustics and background noise you hear, and that makes it harder to understand what the person is saying. The same is true of any microphone.
If you need to pick up voices all over a large room that is acoustically live and noisy, you would probably need to install more than one PZM-11LL so that each mic would be close to the people speaking. Ideally these mics would feed into an automatic (gated) mixer, which turns on only one mic at a time. That makes the speech clearer.