1. Syllables and Stress, part II
March 3, 2014

2. Where Things Stand Your mid-terms are still being graded.
Your first production exercises are, too.
The mid-terms will hopefully be back by Wednesday…
And the production exercises some time after that.
For the next couple of weeks, we’ll be focusing on acoustics.
Note: acoustics is hard.
The final exam has been scheduled!
Tuesday, April 29th, 3:30 – 5:30 pm
Location TBA

3. Intensity Two related concepts are acoustic power and intensity.
Power is just the square of amplitude.
P = A2
The intensity of a sound is its power relative to the power of some reference sound.
Intensity is usually measured in decibels (dB).
Decibels is a measure of intensity with reference to the quietest sound human ears can hear.

4. Some Numbers
The intensity of a sound x can be measured in bels, where a bel is defined as:
= log10 (x2 / r2)
r2 is the power of the reference sound
x2 is the power of sound x.
A decibel is a tenth of a bel.
Some typical decibel values:
30 dB Quiet library, soft whispers
40 dB Living room, refrigerator
50 dB Light traffic, quiet office
60 dB Normal conversation

5. Numbers, continued Some typical decibel values:
70 dB Vacuum cleaner, hair dryer
80 dB City traffic, garbage disposal
90 dB Subway, motorcycle, lawn mower
100 dB Chain saw, pneumatic drill
120 dB Rock concert in front of speakers, thunderclap
130 dB Pain threshold
140 dB Gunshot blast, jet plane
180 dB Rocket launching
Bold = sustained exposure can cause hearing damage
Red = pain, immediate damage

6. Intensity Interactions
Perceived loudness depends on frequency, as well as amplitude.
Mid-range frequencies sound louder than low or extremely high frequencies.
100 Hz
250 Hz
440 Hz
1000 Hz
4000 Hz
10000 Hz

7. An Interesting Fact Some vowels are louder than others
dB of different vowels relative to (Fonagy, 1966):
: 0.0
[e] : -3.6
[o] : -7.2
[i] : -9.7
[u] :
Why?

8. Another Interesting Fact
Some vowels are inherently longer than others.
Data from Swedish (Elert, 1964):
long short
high [i y u] 140 msec 95
mid
low
Why?

9. Frequency and Vowels
In the mystery tone language exercise, you may have noticed that the fundamental frequency of [i] was slightly higher than that of [a], for the same tones

10. “Intrinsic” Pitch
It’s been observed that F0 is usually higher for high vowels than for low vowels
[i] 183 Hz
[e] 169
[æ] 162
[a] 163
[o] 170
[u] 182
Data from Lehiste & Peterson (1961) for American English

11. The “Tongue Pull” Hypothesis (Honda, 2004):
Raising the tongue for high vowels also raises the larynx
The cricoid cartilage rises up and around the spine…
Thus stretching the vocal folds
and increasing longitudinal tension.

12. An Intrinsic Summary High Vowels Low Vowels Intensity Less More
Duration Shorter Longer
F0 Higher Lower
A word of caution:
All of these factors (intensity, duration, F0) factor into perceived prominence and stress.

13. Sonority Loudness is also a highly context-dependent measure.
Can vary wildly within speaker, from speaker to speaker, from room to room, and across speaking contexts.
However, all things being equal, some speech sounds are louder than others.
Course in Phonetics:
“The sonority of a sound is its loudness relative to that of other sounds with the same length, stress and pitch.”

14. From Ladefoged

15. A Sonority Scale low vowels high vowels glides high sonority liquids
nasals
fricatives
stops
high sonority
low sonority
Write this on the board

16. Sonority and Syllables
An old idea (e.g., Pike, 1943): syllables are organized around peaks in sonority.
This is the Sonority Sequencing Principle (SSP).
Example: [bæd] is a well-formed syllable in English.
[æ]
[b] [d]
high sonority
low sonority

17. Sonority and Syllables
An old idea (e.g., Pike, 1943): syllables are organized around peaks in sonority.
This is the Sonority Sequencing Principle (SSP).
Example: [blænd] works well, too.
[æ]
[l] [n]
[b] [d]
high sonority
low sonority

18. Technical Terms sonority peak [æ] [l] [n] [b] [d] high sonority
low sonority

19. Technical Terms The sonority peak forms the nucleus of the syllable.
[æ]
[l] [n]
[b] [d]
nucleus
high sonority
low sonority

20. Technical Terms The sonority peak forms the nucleus of the syllable.
The sounds that precede the nucleus form the syllable onset.
[æ]
[l] [n]
[b] [d]
onset
high sonority
low sonority

21. Technical Terms The sonority peak forms the nucleus of the syllable.
The sounds that precede the nucleus form the syllable onset.
The sounds that follow the nucleus form the syllable coda.
[æ]
[l] [n]
[b] [d]
coda
high sonority
low sonority

22. Technical Terms The sonority peak forms the nucleus of the syllable.
The sounds that precede the nucleus form the syllable onset.
The sounds that follow the nucleus form the syllable coda.
Together, the nucleus and coda form the syllable rhyme.
[æ]
[l] [n]
[b] [d]
rhyme
high sonority
low sonority

23. Some basic principles
Onsets must rise in sonority towards the syllable peak.
Examples:
stop - {liquid/glide} ‘play’ ‘quick’
fricative - {liquid/glide} ‘fling’ ‘thwack’
[s] - {liquid/nasal/glide} ‘slide’ ‘snow’ ‘sweet’
What onset clusters should be ruled out?
Can you think of any English examples where this principle might not work?

24. Some basic principles
Codas must drop in sonority away from the syllable peak.
Examples:
nasal - {fricative/stop} ‘tenth’ ‘hand’
liquid - {fricative/nasal/stop} ‘help’ ‘helm’ ‘heart’
fricative - stop ‘test’
What coda clusters should be ruled out?
Can you think of any English examples where this principle might not work?

25. Other Problems The Sonority Sequencing Principle doesn’t always work.
How can we define a “syllable”?
An alternative idea: each syllable is a “chest pulse” (Stetson, 1951)
It turns out this doesn’t work, either.
Chest muscles don’t necessarily contract for each syllable (Ladefoged, 1967)
Any better ideas?

26. Interesting Patterns Check out the following words: Atlantic atrocious
America arcade
astronomy arthritic
When is the first vowel a ?
Is there a difference between the /t/ in ‘atrocious’ and the /t/ in ‘Atlantic’?
Why?

27. Syllables “defined”
“Syllables are necessary units in the organization and production of utterances.” (Ladefoged, 1982)
The construct of a “syllable” can account for a variety of interesting phonological patterns:
Vowel reduction in unstressed syllables in English.
Fricatives and stops devoice at the end of syllables in German, Russian (and many other languages)
Place contrasts disappear in coda position in Japanese (and many other languages)
Voiceless stops are aspirated at the onset of stressed syllables in many Germanic languages.

28. Back to Stress
Stress is a suprasegmental property that applies to whole syllables.
Stressed syllables are higher in pitch (usually)
Stressed syllables are longer (usually)
Stressed syllables are louder (usually)
Stressed syllables reflect more phonetic effort.
The combination of these factors give stressed syllables more prominence than unstressed syllables.

29. Stress: Pitch
(N)
(V)
Complicating factor: pitch tends to drift downwards at the end of utterances

30. Stress: Intensity (N) (V)
Perception of stress is highly correlated with the area under the intensity curve

31. “Phonetic Effort”
Voiceless stops are more aspirated at the onset of stressed syllables in English
Vowels are often reduced to in unstressed syllables in English.
There is less coarticulation across syllable boundaries in stressed syllables.
X-Ray microbeam study (deJong et al., 1993); two utterances:
I said put the TOAST on the table, not the napkins!
I said PUT the toast on the table, don’t throw it!

32. X-ray microbeam data

33. Varying Levels of Stress/Prominence
English has both primary and secondary stress.
Example: “exploitation”
vowel X X X X
full vowel X X X
stress X X
tonic accent X