With financial support from Sanders and Hubbard, Bell hired Thomas Watson as his assistant,[N <answer>1</answer>5] and the two of them experimented with acoustic telegraphy. On June 2, <answer>1</answer>875, Watson accidentally plucked one of the reeds and Bell, at the receiving end of the wire, heard the overtones of the reed; overtones that would be necessary for transmitting speech. That demonstrated to Bell that only one reed or armature was necessary, not multiple reeds. This led to the "gallows" sound-powered telephone, which could transmit indistinct, voice-like sounds, but not clear speech.
How many reeds did Bell conclude he needed?
1