computer science

Spoken dialog system

Spoken dialog system is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Spoken dialog system rather than just read about it. In short: A spoken dialog system (SDS) is a computer system able to converse with a human with voice. It has two essential components that do not exist in a written text dialog system: a speech recognizer and a text-to-speech module (written text dialog systems usually use other input systems provided by an OS).

Key takeaways

Spoken dialog system belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Spoken dialog system to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Spoken dialog system from memory before moving on to harder problems.

Reference excerpt

A spoken dialog system (SDS) is a computer system able to converse with a human with voice. It has two essential components that do not exist in a written text dialog system: a speech recognizer and a text-to-speech module (written text dialog systems usually use other input systems provided by an OS). It can be further distinguished from command and control speech systems that can respond to requests but do not attempt to maintain continuity over time.

Components An automatic speech recognizer (ASR) decodes speech into text. Domain-specific recognizers can be configured for language designed for a given application. A "cloud" recognizer will be suitable for domains that do not depend on very specific vocabularies. Natural language understanding transforms a recognition into a concept structure that can drive system behavior. Some approaches will combine recognition and understanding processing but are thought to be less flexible since interpretation has to be coded into the grammar. The dialog manager controls turn-by-turn behavior. A simple dialog system may ask the user questions then act on the response. Such directed dialog systems use a tree-like structure for control; frame- (or form-) based systems allow for some user initiative and accommodate different styles of interaction. More sophisticated dialog managers incorporate mechanisms for dealing with misunderstandings and clarification. The domain reasoner, or more simply the back-end, makes use of a knowledge base to retrieve information and helps formulate system responses. In simple systems, this may be a database which is queried using information collected through the dialog. The domain reasoner, together with the dialog manager, maintain the context of interaction and allows the system to reflect some human conversational abilities (for example using anaphora). Response generation is similar to text-based natural language generation, but takes into account the needs of spoken communication. This might include the use of simpler grammatical constructions, managing the amount of information in any one output utterance and introducing prosodic markers to help the human participant absorb information more easily. A complete system design will also introduce elements of lexical entrainment, to encourage the human user to favor certain ways of speaking, which in turn can improve recognition performance. Text-to-speech synthesis (TTS) realizes an intended utterance as speech. Depending on the application, TTS may be based on concatenation of pre-recorded material produced by voice professionals. In more complex applications TTS will use more flexible techniques that accommodate large vocabularies and that allow the developer control over the character ("personality") of the system.

Varieties of systems Spoken dialog systems vary in their complexity. Directed dialog systems are very simple and require that the developer create a graph (typically a tree) that manages the task but may not correspond to the needs of the user. Information access systems, typically based on forms, allow users some flexibility (for example in the order in which retrieval constraints are specified, or in the use of optional constraints) but are limited in their capabilities. Problem-solving dialog systems may allow human users to engage in a number of different activities that may include information access, plan construction and possible execution of the latter. Some examples of systems include:

Information access: Weather, trains schedules, stock quotes, directory assistance. Transactional: credit card and bank enquiries; ticket purchases. Maintenance: Technical support including documentation access and diagnostic testing. Tutoring: For education, such as physics or math, and language learning. Entertainment and chatting

History Pionieers in dialogue systems are companies like AT&T (with its speech recognizer system in the Seventies) and CSELT laboratories, that led some European research projects during the Eighties (e.g. SUNDIAL) after the end of the DARPA project in the US.

References The field of spoken dialog systems is quite large and includes research (featured at scientific conferences such as SIGdial and Interspeech) and a large industrial sector (with its own meetings such as SpeechTek and AVIOS).

The following might provide good technical introductions:

Michael F. McTear, Spoken Dialogue Technology Gabriel Skantze, Error Handling in Spoken Dialogue Systems, 2007: chapter 2, Spoken dialogue systems. Pirani, Giancarlo, ed. Advanced algorithms and architectures for speech understanding. Vol. 1. Springer Science & Business Media, 2013. ISBN 978-3-540-53402-0

Worked examples

Example 1 — a first encounter with Spoken dialog system

Start with the simplest possible case. Write down what Spoken dialog system claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Spoken dialog system before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Spoken dialog system ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Spoken dialog system

In research: Spoken dialog system appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Spoken dialog system in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Spoken dialog system is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computational linguistics, Multimodal interaction, Speech recognition, so understanding it makes those chapters shorter.
In everyday life: Look for Spoken dialog system outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Spoken dialog system in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Spoken dialog system means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Spoken dialog system out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Spoken dialog system in simple terms?

Why does Spoken dialog system matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Spoken dialog system?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Spoken dialog system.