SOME NEW SOUNDS have been heard across the land this week: the voices of members of Congress in House debate. Until Monday, citizens outside the Capitol galleries had no way to hear proceedings on the House floor. They had to rely on broadcasters' summaries or statements that lawmakers recorded elsewhere. Now Speaker Thomas P. O'Neill (D-Mass.) is letting broadcasters use the sound carried on the official system that transmits floor proceedings to members' offices. Some networks and stations have already carried excerpts from this week's debates.

The new system is a welcome first step. But it has practical limitations. The microphones do not pick up the background sounds that convey a real sense of the chamber's atmosphere. More important, reporters may broadcast only from a gallery off the floor, where they cannot see what is going on. In contrast, the Senate, during its Panama debates, allowed National Public Radio to broadcast from a balcony. The correspondent could watch events, identify all speakers instantly, describe roll calls and inform listeners of off-mike events such as quick conferences among senators. That kind of on-the-spot, gavel-to-gavel coverage is practically ruled out in the House so far.

The system also embodies Mr. O'Neill's view, affirmed by the House on Wednesday, that Congress itself should operate the mikes and, in the future, television cameras. As a matter of principle, we and most broadcasters object to that. What remains to be seen is how much day-to-day difference House control will make. If the House does provide first-class technical services and grants broadcasters enough access and flexibility, the public will certainly gain. We trust that Mr. O'Neill will move quickly to expand broadcast opportunities so people everywhere can hear and eventually see more of their representatives at work.