Speech analysis with Praat

Paul Trilsbeek

DoBeS training courseJune 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:

Picture window

• WMF output:

Exercises