Speech analysis with Praat
Paul Trilsbeek
DoBeS training course
June 2007
Sources used
• Sidney Wood’s “Praat beginners’
manual”
• Pascal van Lieshout’s “Praat short
tutorial”
• Links for both on www.praat.org
Outline
• First half: theoretical overview
– What is Praat
– General Praat interface
– Several kinds of analyses
– Creating graphical output
• Second half: practice
– Hands-on experience with some exercises
What is Praat? (1)
• “Praat” = “speak” (Dutch)
• “Doing phonetics by computer”
• Analysis and reconstruction of speech
signals
• Developed by 2 phoneticians from the
University of Amsterdam, Paul Boersma
and David Weenink
What is Praat? (2)
• Program running on most operating
systems (Windows 95 to XP, Mac OS
9/X, Linux, several kinds of Unix …)
• Available for free from www.praat.org
under GNU General Public License (inc.
source code)
General Praat interface
• Praat objects window
– List of praat ‘objects’: sounds, analyzed
sounds, synthesized sounds …
– Buttons for editing, viewing, applying
analyses, etc.
• Praat picture window
– For creating and manipulating graphical
output
General Praat interface
Getting help
• Praat help menu
• Praat web site (same content)
• 2 tutorials mentioned before (see
praat.org)
• Praat discussion list
Recording a sound
Loading a sound
• Long vs. short sound file: memory
• Extract part
• Extract segments from annotated long
sound
Annotating a sound
• Create text annotations on different
levels
• Praat objects can be created from
segments
Annotating a sound
Praat Edit window
•
•
•
•
Waveform display
Segment play buttons
Zoom buttons
Several other views of analyses
– Spectrogram
– Pitch analysis
– Intensity analysis
– Formant analysis
– Pulses
Praat Edit window
Spectral analysis
• Fourier theorem: “any given signal can
be constructed by addition of an infinite
number of sine waves with specific
frequencies, amplitudes and phases”.
• Fourier analysis: “ finding out the
frequencies, amplitudes and phases of
these sine waves for a given signal”
Spectral analysis
Spectral analysis
Spectrogram
• Spectrum with a third dimension
added: time.
Pitch analysis
• Shows fundamental frequency where
one can be detected
• Not always correct, octave jumps often
occur, depending on the quality of the
signal. Can be corrected manually.
Pitch analysis
Intensity analysis
• Shows the intensity contour of a signal
Intensity analysis
Formant analysis
• Frequency bands with higher acoustic
energy caused by resonances in the
vocal tract, mouth and nose cavities
• Different vowels and fricative
consonants have different formant
structures
Formant analysis
Manipulation
• Add or delete pulses
• Modify duration (timing)
• Modify pitch contour
Manipulation
Picture window
• Clicking “draw” button will draw graphic
into picture window
• Some modifications can be done in the
picture window
• Text can be added
Picture window
Picture window
• Export picture as EPS (Encapsulated
PostScript) for further use in media to
be printed. Adobe Illustrator can be
used to further edit the EPS file
• Export picture as Windows Meta File
(Windows only) for media to be shown
on screen (PowerPoint presentation)
Picture window
• EPS output:
0.6564
0
–0.5085
0
1.76992
Time (s)
Picture window
• WMF output:
0.6564
0
-0.5085
0
1.76992
Time (s)
Exercises