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<Paper uid="N04-3002">
  <Title>ITSPOKE: An Intelligent Tutoring Spoken Dialogue System</Title>
  <Section position="3" start_page="0" end_page="0" type="metho">
    <SectionTitle>
2 Application Description
</SectionTitle>
    <Paragraph position="0"> ITSPOKE is a speech-enabled version of the Why2-Atlas (VanLehn et al., 2002) text-based dialogue tutoring system. As in Why2-Atlas, a student rst types a natural language answer to a qualitative physics problem.</Paragraph>
    <Paragraph position="1"> In ITSPOKE, however, the system engages the student in a spoken dialogue to correct misconceptions and elicit more complete explanations.</Paragraph>
    <Paragraph position="2"> Consider the screenshot shown in Figure 1. ITSPOKE rst poses conceptual physics problem 58 to the student, as shown in the upper right of the gure. Next, the  user types in a natural language essay answer (as shown in the essay box in the middle right of Figure 1), and clicks SUBMIT. ITSPOKE then analyzes the essay, after which the spoken dialogue with the student begins. During the dialogue, the system and student discuss a solution to the problem relative to the student's essay explanation, using spoken English. At the time the screenshot was generated, the student had just said free fall. After each system or student utterance, the system prompt, or the system's understanding of the student's response, respectively, are added to the dialogue history (as shown in the dialogue box in the middle left of Figure 1).1 At some point later in the dialogue, the system will eventually ask the student to edit the typed essay explanation. The system will then either express satisfaction and end the tutoring for the current problem, or continue with another round of spoken dialogue interaction and typed essay revision. Upon completing the problem, the student is presented with an example of an ideal essay.</Paragraph>
    <Paragraph position="3"> Another excerpt with ITSPOKE is shown in Figure 2.</Paragraph>
  </Section>
  <Section position="4" start_page="0" end_page="0" type="metho">
    <SectionTitle>
3 System Architecture
</SectionTitle>
    <Paragraph position="0"> The architecture of ITSPOKE is shown in Figure 3. Student speech is digitized from microphone input and sent to the Sphinx2 automatic speech recognizer. Sphinx2's best hypothesis is then sent to Why2-Atlas for syntactic and semantic analysis (Ros*e, 2000), discourse and domain processing (Jordan et al., 2003), and nite-state dialogue management (Ros*e et al., 2001). The tutor's text output is sent to the Cepstral text-to-speech system, and played through a speaker or headphone.</Paragraph>
    <Paragraph position="1"> ITSPOKE is implemented in Python and acts as a proxy server between the Why2-Atlas server and client.</Paragraph>
    <Paragraph position="2"> ITSPOKE monitors the XML being sent between the two and decides what text should be spoken and when to listen. After speech recognition, ITSPOKE submits what it thinks the student said to Why2-Atlas (as if the student had typed it). Sphinx2's C API is tied into Python by using SWIG to generate a Python wrapper API. Cepstral's speech synthesis engine is currently run out of process using a fork/exec, but we plan to use SWIG to tie its C API into Python in the future. For speed, we have in-ITSPOKE: I didn't understand. What force acts on all objects within close proximity to earth? STUDENT: uh the force of gravity ITSPOKE: Fine. Besides the Earth's gravitational force, are there any other forces acting on the person, keys, and elevator after the release? STUDENT: no ITSPOKE: Yep. Thus, keep in mind that after the release, the only force on the person, keys, and elevator is the force of gravity. If gravity is the only force acting on an object, will it be moving or staying still? STUDENT: it will be moving ITSPOKE: Fine. Not only are the person, keys, and elevator moving, they have only gravitational forces on them. When an object is falling and has only gravitational force on it, it is said to be in what? STUDENT: freefall ITSPOKE: Good. Thus, after the release the only force on the keys and man is the downward force of earth's gravity, so they are in freefall. Before the release, what is the relationship between the man's velocity and the keys' velocity? STUDENT: they're equal  stalled Sphinx2 and Cepstral on the ITSPOKE machine.</Paragraph>
    <Paragraph position="3"> The dashed line in the gure re ects that Why2-Atlas can be installed on a different machine, although we are currently running it on the same machine.</Paragraph>
  </Section>
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