Mrs Hughes: I don't know. Maybe.(0.5 seconds) Sometimes.
(Down ton Abbey Season1 Episode1)
Within-turn silence refers to silence last 0.3 seconds and 0.2 seconds. The former silence means Mrs Hughes is organizing her utterance while the latter one is used to remind Mr Carson that he could have his own dream of living a different life in the future. Therefore, pause is usually been used as one of the rhetorical means in speech to emphasize the tone or the meaning. Silence last 2.0 seconds is gap, one of the Inter-turn silence which come into being when Mr Carson, the selected next speaker fails to start his turn.

Third, "Turn-silence" , as what can be see in the process of 1(a), means silence which the selected party as N(next speaker) keeps when C(current speaker) gives an end to the current Turn. Besides, being able to function independently as a turn at talk, turn-silence is also called significant silence because it carries conversational implicature. Here is an example:
Example2:
Jan: Dave, I'm going to the store.
Dave: (2.0)
Jan: Dave?
Dave: (2.0)
Jan: Dave-is something wrong?
Dave: What? What's wrong?
Jan: Never mind.

In the example 1, Jan calls Dave at the beginning which indicates that she selects him as the next speaker. After she finishes her sentence, Dave is suppose to start a new turn. However, Dave gives no reply but keeps silent even after Jan calls him twice, which is typical turn-silence. It is natural for Jan to wonder why he remains silent and doubt his true intentions. In this case, Dave's silence is full of implications to Jan such as his objection of Jan's going shopping. 英汉会话语篇中沉默的认知语用探析(4):http://www.751com.cn/yingyu/lunwen_8927.html