331 research outputs found
Towards a Knowledge Graph based Speech Interface
Applications which use human speech as an input require a speech interface
with high recognition accuracy. The words or phrases in the recognised text are
annotated with a machine-understandable meaning and linked to knowledge graphs
for further processing by the target application. These semantic annotations of
recognised words can be represented as a subject-predicate-object triples which
collectively form a graph often referred to as a knowledge graph. This type of
knowledge representation facilitates to use speech interfaces with any spoken
input application, since the information is represented in logical, semantic
form, retrieving and storing can be followed using any web standard query
languages. In this work, we develop a methodology for linking speech input to
knowledge graphs and study the impact of recognition errors in the overall
process. We show that for a corpus with lower WER, the annotation and linking
of entities to the DBpedia knowledge graph is considerable. DBpedia Spotlight,
a tool to interlink text documents with the linked open data is used to link
the speech recognition output to the DBpedia knowledge graph. Such a
knowledge-based speech recognition interface is useful for applications such as
question answering or spoken dialog systems.Comment: Under Review in International Workshop on Grounding Language
Understanding, Satellite of Interspeech 201
Directionality of THz emission from photoinduced gas plasmas
Forward and backward THz emission by ionizing two-color laser pulses in gas
is investigated by means of a simple semi-analytical model based on Jefimenko's
equation and rigorous Maxwell simulations in one and two dimensions. We find
the emission in backward direction having a much smaller spectral bandwidth
than in forward direction and explain this by interference effects. Forward THz
radiation is generated predominantly at the ionization front and thus almost
not affected by the opacity of the plasma, in excellent agreement with results
obtained from a unidirectional pulse propagation model
Two-Staged Acoustic Modeling Adaption for Robust Speech Recognition by the Example of German Oral History Interviews
In automatic speech recognition, often little training data is available for
specific challenging tasks, but training of state-of-the-art automatic speech
recognition systems requires large amounts of annotated speech. To address this
issue, we propose a two-staged approach to acoustic modeling that combines
noise and reverberation data augmentation with transfer learning to robustly
address challenges such as difficult acoustic recording conditions, spontaneous
speech, and speech of elderly people. We evaluate our approach using the
example of German oral history interviews, where a relative average reduction
of the word error rate by 19.3% is achieved.Comment: Accepted for IEEE International Conference on Multimedia and Expo
(ICME), Shanghai, China, July 201
CHORUS Deliverable 4.5: Report of the 3rd CHORUS Conference
The third and last CHORUS conference on Multimedia Search Engines took place from the 26th to the 27th of May 2009 in Brussels, Belgium. About 100 participants from 15 European countries, the US, Japan and Australia learned about the latest developments in the domain. An exhibition of 13 stands presented 16 research projects currently ongoing around the
world
3D numerical simulations of THz generation by two-color laser filaments
Terahertz (THz) radiation produced by the filamentation of two-color
pulses over long distances in argon is numerically investigated using a
comprehensive model in full spacetime resolved geometry. We show that the
dominant physical mechanism for THz generation in the filamentation regime at
clamping intensity is based on quasi-dc plasma currents. The calculated THz
spectra for different pump pulse energies and pulse durations are in
agreement with previously reported experimental observations. For the same
pulse parameters, near-infrared pump pulses at 2 m are shown to generate a
more than one order of magnitude larger THz yield than pumps centered at 800
nm
3D numerical simulations of THz generation by two-color laser filaments
Terahertz (THz) radiation produced by the filamentation of two-color pulses over long distances in argon is
numerically investigated using a comprehensive model in full space-time resolved geometry.
We show that the dominant physical mechanism for THz generation in the filamentation regime at
clamping intensity is based on quasi-dc plasma currents. The calculated THz spectra for different pump
pulse energies and pulse durations are in agreement with previously reported experimental observations.
For the same pulse parameters, near-infrared pump pulses at 2~m are shown to generate a more
than one order of magnitude larger THz yield than pumps centered at 800 nm
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