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

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 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

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

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