About
Section 1
Section 2
Created by Amanda Shultz
Section 3
Links
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Target
Audience
Objectives
Orientation
Help
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• This individualized instruction in PowerPoint was created for
graduate students and instructors with a background in
phonology and phonetics who want to learn more about
acoustic analysis.
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• After using this instructional tool, you will:
• Have a better understanding of what acoustics is and how it relates to
phonology and phonetics
• Know how to use the basic functions of Praat
• Know how to measure voice onset time (VOT)
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• This instructional tool may best be used with two computer monitors, one to view
PowerPoint and the other to download the necessary items and use Praat.
• Note that there are links to websites. Once you click on a website link, a window will
appear with the website. You will need to click on the PowerPoint screen again to return to
this instructional tool.
• There are three sections to this instructional tool:
• Section 1: Background Information
• Section 2: Using Praat
• Section 3: Measuring Voice Onset Time (VOT)
• You can access the three sections from the main menu.
• To access the main menu from any page, click the “Main” button in the lower left corner.
• Each section has its own page.
• To access the section page of the section you are currently viewing, click the “Sec” button in
the lower left corner.
• Each page has navigation buttons.
• Click the “Prev” button to view the previous page.
• Click the “Next” button to view the next page in the progression of this instructional tool.
• Click the “Back” button to view the last page you saw.
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Need Help?
• If you are experiencing problems with this
instructional tool, feel free to email Amanda
at shultz1@purdue.edu.
• If you feel like you need more background
information, check out the links page here.
• You can also access a helpful Praat
beginners’ guide here.
• For technical Praat questions, you can search
the Praat manual by clicking the “Help”
button, which is located in the object window
as shown in the screen shot below.
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What you
should know
Praat
VOT
Helpful Links
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• Since this instructional tool
is geared to those who
already have an
understanding of phonetics
and phonology, you should
be familiar with:
• The International Phonetic
Alphabet
• The difference between
phonetics and phonology
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• To put it simply, acoustics is the study of waves. To people interested
in speech, acoustics is the study of the sound waves created by human
speech.
• For the purposes of this instructional tool, Praat is an acoustic analysis
computer program, which is free off the internet. You can use Praat
to take acoustic measurements (e.g., pitch of a sound wave) from
audio files of speech and to make markings within a text file to label
and keep track of the contents of the audio file.
• Praat was designed by Paul Boersma and David Weenick.
• You can access their website for Praat here.
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Definitions needed to understand voice onset time (VOT):
• Phonation (Voicing)—vibration of the vocal folds
which produces a periodic waveform
• Sound—a vibration that produces a periodic wave
form (phonation/voicing creates a sound)
• Noise—a vibration that lacks periodicity (aspiration
creates noise)
• Burst—a pressure impulse that can be seen in the
waveform after the release of a stop/plosive
Putting it all together:
• VOT—the time that elapses between the burst of a
plosive and the onset of phonation.
We will focus on the VOT of the plosives /b/ and /p/.
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• Voiced Stops:
• If the onset of phonation occurs first and the burst occurs second, then the VOT
will have a negative value or if the phonation occurs at the burst then VOT
would be 0 milliseconds (ms). During the time between the onset of phonation
and the burst, there should be some periodicity (sound).
• Voiced Stops: VOT ≤ 0
• E.g., Spanish /b/
• Voiceless Stops:
• If the burst occurs first and the onset of phonation occurs second, then the VOT
will have a positive value. During the time between the burst and the onset of
phonation, there may be some noise from aspiration, but there should not be
any periodicity (sound).
• Short Lag/Unaspirated Stops: 0 ms < VOT < 30 ms
• E.g., Spanish /p/
• Long Lag/Aspirated Stops: VOT > 30 ms
• E.g., English /p/
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• This diagram represents a
timeline in which the
mouth closes (“blockage”)
and releases.
• The zigzag represents the
timing of the voicing.
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Instructions
Video 1
Video 2
Assessment
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1) Go to Praat’s website and download the program on your
computer.
2) Go to this website and download the sound file labeled “Plosive1”.
3) Save “Plosive1” to your computer in a location that you will
remember.
4) Open Praat. The download should have created a shortcut on your
desktop.
5) Close the “Praat Picture” window; we will not be using this.
6) In the “Praat Objects” window, click “Read.” Then click “Read from
file.”
7) Find “Plosive1” in the place where you just saved it. Click on
“Plosive1” in the window and then click “Open.”
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8) “1. Sound Plosive1” will appear in the Objects list as the first item.
9) Click the “Annotate” button located to the right of the Objects list. Then
click “To TextGrid…”
10) A window entitled, “Sound: To TextGrid” will appear. Just click “OK”. (We
will save naming tiers for another time.)
11) “2. TextGrid Plosive1” will appear in the Objects list as the second item.
12) Highlight both the sound file and the TextGrid within the objects window.
(Do this by holding shift while clicking or click and then drag your mouse.)
13) Click the “Edit” button located to the right of the Objects list.
14) Now you will see a new window appear. This shows the waveform and
spectrogram of the sound file as well as the TextGrid which, right now,
includes three tiers, labeled 1, 2, and 3 along the left side of this window.
Congratulations, you have now officially opened a sound file/TextGrid in Praat!
See the “Beginning Praat Video” on the next page for a
demonstration of these instructions.
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“Beginning Praat Video”
• Click the “VIDEO” button above
to see a demonstration of the
previous set of instructions for
using Praat.
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“Praat Functions Video”
• Click the “VIDEO” button above
to see a demonstration of some
of the basic functions in Praat.
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Click to begin the activity!
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Instructions
Diagram
Video
Assessment
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1) Find the word that contains the initial stop consonant that you
want to measure.
2) Zoom in on the beginning of the word to find the burst of the
stop.
•
Remember that the burst will make an impulse in the wave at the
beginning of the word.
3) Place a boundary where the pulse begins to move from the
dotted blue (zero) line.
4) Zoom out to see where the periodicity of voicing begins.
5) Zoom back in to see exactly where the periodicity does begin.
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6) If you are not sure, you can listen to a selection of the speech that
you think should be between the burst and the onset of voicing.
Listening with a good pair of headphones is a good way to double
check your work.
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If VOT is positive, then the onset of voicing should be noise, while the
following vowel should be a periodic sound.
If VOT is negative, then you have a waveform before the burst.
7) Place a boundary at the onset of voicing.
8) Click on the space between the two boundary lines and record the
duration. This is the VOT. Remember:
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•
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If the burst comes before the onset of voicing, then VOT is positive.
If the burst comes after the onset of voicing, then VOT is negative.
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This means that you would have to put a negative sign in front of the
duration that Praat calculated between the onset of voicing and the
burst. (There is no reason for Praat to record a negative duration.)
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Praat Screen Shot
• The above screen shot of Praat
has arrows that point to
important features.
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“VOT Video”
• Click the “VIDEO” button above
to see a demonstration of how to
measure VOT in Praat.
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Click to begin the quiz!
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Praat Website
Sample Sounds
Beginning
Praat Video
Praat Functions
Video
Praat VOT
Video
Beginners’
Guide to Praat
Wikipedia:
Acoustics
Wikipedia:
VOT
How to read a
spectrogram
Mystery
Spectrogram
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• If I wanted to upload a sound
file into Praat, what would I click
first?
Section 2: Using Praat
Click on the picture in
response to the question.
Next Question
• If I wanted to view just the
part highlighted in pink, what
would I click?
Section 2: Using Praat
Click on the picture in
response to the question.
Next Question
• If I wanted to view the Praat
manual, what would I click?
Section 2: Using Praat
Click on the picture in
response to the question.
Next Question
• Click on the part of the screen
that shows the duration of the
part of the sound that is
highlighted.
Section 2: Using Praat
Click on the picture in
response to the question.
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1. Approximately, what is the
VOT for the word “Bat” in the
“Plosive1” sound file?
Section 3:
Measuring VOT
a.
b.
c.
d.
1ms
4 ms
12 ms
51 ms
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2. Approximately, what is the
VOT for the word “Pat” in the
“Plosive1” sound file?
Section 3:
Measuring VOT
a.
b.
c.
d.
88 ms
62 ms
54 ms
10 ms
Next Question
3. Approximately, what is the
VOT for the word “Bit” in the
“Plosive1” sound file?
Section 3:
Measuring VOT
a.
b.
c.
d.
85 ms
72 ms
35 ms
13 ms
Next Question
4. Approximately, what is the
VOT for the word “Pit” in the
“Plosive1” sound file?
Section 3:
Measuring VOT
a.
b.
c.
d.
89 ms
95 ms
109 ms
125 ms
Click to see helpful links
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