阅读下面的短文，然后从A-F选项中，为每一小段选择合适的标题, 并把答案写在答案卷上。

A. The most common problem is a “wandering” mind B. Selective listening is also a mental barrier C. Listening isn’t an easy skill to master D. Attitude can also influence good listening E. Noise and background music makes listening more difficult F. Listening is also related to the level of the listener’s knowledge

_____________
Listening is not as easy as someone thought. Even good listeners may recall only fifty percent of what they hear. Retention, the ability to remember and recall information, decreases about twenty to twenty-five percent after a few days. So no matter how well you listen in class, you’re always going to have to refresh your memory before a test! Unfortunately, many people have poor listening habits, and little listening training. To improve your listening skills, it’s important to understand what causes poor listening.
___________
If you find it difficult to concentrate solely on what a speaker is saying, there’s a good reason. The mind processes information much faster than a speaker can speak. The brain can process over 500 words per minute, while the average speaker talks at a rate of 124 to 250 words per minute. That means the mind can hear what’s being said and can think about something else at the same time.
____________
If you have a negative idea about the speaker or the topic, you’ll find it difficult to listen attentively. Hostile or captive audiences often have more difficultly listening than do favorable or voluntary ones.
____________
If a speaker speaks “above the heads” of an audience, people find it difficult to concentrate. Speakers who use unfamiliar words or who use incomplete explanations make it more difficult to listen. Speakers who “speak down” to audiences, failing to acknowledge what the audience already knows, also create mental blocks.
___________
When people listen selectively, they simply block out what they don’t want to hear. For instance, many people have habits that are dangerous to their health, like smoking. However, they often choose to block out what a speaker says about health risks. They may listen to a speech and think that the speaker’s message applies to other people, not them. In other words, they hear what they want to hear and ignore what they don’t want to hear.