Transcript ACOUSTIC PHONETICS Seeing & Measuring Speech sounds

ACOUSTIC PHONETICS
SEEING & MEASURING SPEECH SOUNDS
Linguistics 187 / Cultural Anthropology 187 / English 187 / ICS 151C
Variety in Language: English in the United States
Duke University
Erin Callahan-Price
Spring 2011
I. WHIRLWIND TOUR OF
ACOUSTIC PHONETICS
Preparation for Vowel Workshop with Dr. Erik Thomas
Remember Vowels?
Our Inventory: American English
What was our
Inventory before?
The Great Vowel Shift
What happened?
What does it look like in articulatory and acoustic “space”?
What Will Our Next “Great Vowel Shift” Be?
Vowel Movements
The Push-Pull Effect
The Northern Cities Shift
bit
i
6
1
bet
e
but
4
v
Contrasting
patterns of
vowel shifts:
oh caught
3
æ
o
2
cat
Southern
Shift vs.
Northern
Cities Vowel
Shift
5
cot
The Southern Shift
iy
beat
bit
i
ey
bet
bait
e
æ
bat
ah
2
ay
bite
Great.
Relevant social
questions
for sociolinguists:
• Where are these shifts
happening, and why?
• What can the distribution
of the shift(s) tell us about
social relationships?
• Who talks to who?
• Who migrates where?
• What happens when non-
native English speakers
acquire English in a
shifted area?
Representative social network diagram aggregating connections from Facebook, LinkedIn, MySpac
(from Rowse (2007)
Great, cont.
Relevant practical
(empirical) question
for sociolinguists:
• How can we accurately
and reliably
quantify/measure/calculate
the acoustic changes
constituted by these
shifts?
Analyzing speech production with spectrograms
A First Look
• The main tool phoneticians/linguists use to measure
speech production is a spectrogram, a visual
representation of sound.
Information in Spectrograms:
Measuring sound through the digitization and Sampling Process
From Power Spectrum to Spectogram
In a power spectrum, frequency in Hz is displayed on the xaxis and amplitude is displayed in dB on the y-axis
From Power Spectrum to Spectogram:
A First Look
In a power spectrum, frequency in Hz is displayed on the xaxis and amplitude is displayed in dB on the y-axis
From Power Spectrum to Spectogram
Measuring vowels as rendered on a spectrogram involves
measuring their component resonances, or formants
(isolated above)
“Zooming In” to Syllable Level
• Vowel Plots are produced when the researcher measures the
F0 (fundamental frequency) as shown on the spectrogram for,
say, ten glottal pulses…
• …and then plots some average of those measurements in a
vowel chart.
Finally! Measuring Vowels:
the trenches
• Formant tracks like this allow us to measure
vowels in the speech stream, and compre them
across speakers.
Finally! Measuring Vowels:
the trenches
• After many samples of ONE vowel are taken, we can
move to the next vowel…
• …and the next…and the next…
Finally! Measuring Vowels:
the trenches
• Until we have a vowel plot!
Homework
• Read C.2
• Download praat:
http://www.fon.hum.uva.86nl/praat/download_win.html
http://www.fon.hum.uva.nl/praat/download_mac.html
• BRING LAPTOPS!
II. USING PRAAT TO
MEASURE VOWELS
Preparation for Vowel Workshop with Dr. Erik Thomas
Steps to Recording & [vowel] audio for
analysis
1. Download & install praat.
2. In “Objects” window:
• New Record mono sound
• Read word list (heed, hid, hayed, head, had, hod, hawed, HUD, hoed, hood, who'd, hold, heard)
• Save to list.
3. Highlight “Sound Untitled” and click “View and Edit”
Analysing your Recording
1. In waveform view, highlight one “chunk” of sound (which
is an individual word):
Analysing your Recording
2. Use shortcuts to zoom to navigate praat:
a. Highlight + CTRL+N= Zoom to selection
b. CTRL+O= zoom out
c. CTRL+I= zoom in
d. Tab= play or stop
Format Settings
3. At appropriate view (around 2-3 words or so):
a. Formants  Show Formants
b. Formants Formant Settings
c. Adjust Formant number from around 4-6 to
calibrate formant tracking: TRIAL AND ERROR
TIPS:
-The goal is for the formant tracking (red lines) to match the sound that
you “see” with your eyes. In other words, you want the computer to see
what you see. This is a modeling task.
-Don’t worry about Formants 3-5+. You’re only measuring 1 and 2.
Measuring the Vowel(s)
4. At appropriate view (around 2-3 words or so):
a. Position cursor about in the middle of the selection.
Getting formant values
5. Measuring formants
a. F1= Get first
formant; F2= Get
second formant
b. Record values on
paper or in Excel
Plotting values
6. Arrange your axes like this and plot your vowels:
Just for Fun
• Manipulating and Synthesizing Sound with praat:
• 1. Low/High Pass
• 2. “Change Gender”
• 3. Pitch Manipulation