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There are as many types of corpora as relevant factors which can be
used to define them: speakers, texts, speech type, recording
conditions, tasks and so on. Among this wide range of possible
corpora, we may characterise them according to their intended use:
- 1. Experimental research:
- These corpora are widely used
for speech technology development and assessment. Much of the
basic material was collected several years ago, and more recent
technology requires more advanced materials.
- 1.1 Basic material:
- Numbers, Words, Sentences, Logatoms
- Number of speakers: medium (100--500)
- Several repetitions.
- 1.2 Advanced material:
- Continuous speech, passages, situated dialogue.
- Number of speakers: small to medium (10--200)
- Recently the trend has been to increase the number of speakers in such corpora
- 1.3 Specific databases:
- multi-sensor corpora (Lx), articulatory, acoustic, video databases.
- Number of speakers: small
- These corpora tend to be relatively expensive to collect and
may require sophisticated recording facilities and sensors, as well as
specialised operators.
- 2. General-purpose Telephone corpora:
- These used for speech recognition and coding over the telephone.
These type of corpora are relatively easy to obtain (the speaker only
needs to call a specified telephone number) and relatively cost
effective. However, with advances in communication technology, some of
the problems currently posed by the limited bandwidth and noisy
communication channel of today's telephones can be expected to
disappear.
- Material: word lists, numbers, spelled names
- Number of speakers: large (several hundreds to several thousands)
- 3. Application-oriented corpora:
- For specific tasks and/or environments (many of which involve the
telephone network). By essence of their application specificity, many of
these corpora are not easily reused for other applications.
- Domains: Information retrieval -- travel inquiry (train and flight
information and reservation), leisure activities, telephone services. \\
Vocal dictation -- medical, legal and insurance areas.
- Adverse environments: Car database, Handicap applications.
- Number of speakers: variable (small to medium)
The two extremes in corpus type are on one side very specific corpora
for fundamental research, which may require complex recording
conditions with multi-channel recordings, and a low number of
speakers, and at the other application-specific corpora which may be
recorded over the telephone with a large number of speakers. In
addition to the recorded speech signal, we must highlight the
importance and effort required to ensure that the appropriate
associated information is provided. This associated information
depends heavily on the type of corpus, but at a minimum must include
revelant speaker information, transcriptions (at a miminum an
orthographic transliteration), prompt material in the case of
read-speech corpora, lexica, noise or channel characteristics and
details of the recording configuration.
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Actors in speech resource
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Criteria for assessment of
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Criteria for assessment of
EAGLES SWLG SoftEdition, May 1997. Get the book...