Apr 1999 CO230: Cognitive Science (Question 5)

(a)	Language modeling is a very complex task. Therefore, linguists have defined seven levels of analysis to manage the complexity. Describe five of these levels.	[10]
	One level is prosody which deals with the rhythm and intonation of language. It is an area which is not explored deeply. Its strength can be seen in the creation of poems and religious chants. Another level is phonology, which deals with the sounds that combine to make up language. This area of analysis is important in the development of speech recognition and speech synthesis. Another level is syntax, which deals with the rules that govern the combination of words into meaningingful phrases and sentences and also in the parsing and generation of words and sentences. Another level is pragmatics, which analyses the ways in which languages is used and its effects on the listener. Another level is morphology which analyses the individual components of words that make up a language. It is interested in how prefixes ( un, in, anti, etc) modify the meanings of words and sentences.
(b)	Text-to-speech synthesis often uses templates in a process resembling those used for word recognition. However, there are some disadvantages of using template. Briefly describe two such shortcomings.	[4]
	One shortcoming is that it requires a large amount of memory to store the templates for a small vocabulary of words. Different templates are required for different forms of the same word, e.g. play, played, playing, etc. Another shortcoming is that templates combined to form sentences will not sound natural. Each template is store naturally and do not reflect the various intonations of language e.g. screaming, exclamation, whispering, etc. Moreover, due to the neutral way templates are stored, it will be different to listen unless they are played slowly.
(c)	Natural language analysis is a complex task which is generally broken down into three stages to make natural language easier to understand. Briefly describe the three stages.	[6]
	The firs stage is parsing. In parsing, the syntactic structure if the text is analyzed to ensure that it is well-formed. Its linguistic structure is determined as well. This linguistic structure provides a framework for the next step - semantic interpretation. In semantic interpretation, the text is analyzed to present a semantic representation of it. Knowledge about the words and sentences are employed to aid in the process. Often, the semantic meanings of the text are represented on conceptual graphs. The last stage is world knowledge representation. Knowledge from the knowledge base are added into the internal representation of the text. The result is a representation of the full meaning of the text in the world context.