something important, I like to receive confirmation that I've been heard and understood. A former Significant Other and I once agreed that when she said "I hear you," that meant that she understood what I said. She didn't necessarily agree with me, but the message had (apparently!) been received. Until we agreed on this convention, I would often repeat myself in an attempt to generate some reaction other than her just looking at me, which only annoyed her.
To improve your communication effectiveness, be sensitive to the communication styles of the people with whom you interact. Discuss how much detail is appropriate in status reports or meeting summaries. Agree on which communications should be written, which are suitable for email, and which need to be handled face-to-face. Read the body language of people with whom you speak, to detect when someone is thinking (a furrowed brow or distant gaze) or getting ready to speak (an audible intake of breath).
Consider taking a listening skills class, which teaches ways to hear what people say more effectively and to provide feedback that indicates the message is coming through. If a discussion led to a decision or commitment, summarize the agreement to ensure that all participants share the same understanding. Sometimes a written summary of the key points reveals that not all participants really agreed on the discussion's outcome. Recognize that communication style preferences reflect personality differences, and learn to communicate effectively with people whose natural style might be very different from yours. Remember that they're also wondering why you're talking to them in such a strange way.