12 syllables and stress

7/29/2019 12 Syllables and Stress

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Syllables and Stress

October 24, 2011


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Practicalities Review session on Wednesday.

Mid-term on Friday.

Note: well deal with the outstanding transcription

homeworks on Wednesday

(reference transcriptions will be posted to the course

web page)

On Wednesday, well also take a listen to the accents ofEnglish samples (Scottish + Boston)


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Review: Suprasegmentals

Last time, we learned that there were three kinds of

languages:

1. Tone languages (Chinese, Navajo, Igbo)

lexically determined tone on every syllable or word

2. Accentual languages (Japanese, Swedish)

the location of an accent is lexically marked.

3. Stress languages (English, Russian)

its complicated


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What is Stress? Examples of stress in English:

(V) vs. (N)

(V) vs. (N)

Phonetically, stress is hard to define

I.e., it is hard to measure.

It seems to depend on an interaction of three

quantifiable variables:

Pitch

Duration

Loudness

And also: quality


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Loudness

How do we measure how loud a sound is?

Recall: one parameter of a sinewave is its amplitude.

Peak amplitude (for sound) is the highest sound pressure

reached during a particular wave cycle.

peak-to-peak

amplitude


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Amplitude/Loudness Examples The higher the peak amplitude of a sinusoidal sound, the

louder the sound seems to be.


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RMS amplitude

Peak-to-peak amplitude is sufficient for characterizingthe loudness of sinewaves, but speech sounds are more

complex.

Another method of measuring loudness:

root-mean-square (RMS) amplitude

To calculate RMS amplitude:

1. Square the pressure value of the waveform at each

point (sample) in the sound file

2. Average all the squared values

3. Take the square root of the average


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RMS example

pressure 1 0.707 0 -0.707 -1 -0.707 0 0.707 1

sample 1 2 3 4 5 6 7 8 9

A small sampling of a sinewave has the following

pressure values:

It looks like this (in Excel):


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RMS calculationspressure 1 0.707 0 -0.707 -1 -0.707 0 0.707 1

sample 1 2 3 4 5 6 7 8 9

To calculate RMS amplitude for this sound, first square the

values of each sample:

Then average all the squared values

(1 + .5 + 0 + .5 + 1 + .5 + 0 + .5 + 1) / 9 = 5/9 = .555

Then take the square root of the average

RMS amplitude = .745

square 1 0.5 0 0.5 1 0.5 0 0.5 1sample 1 2 3 4 5 6 7 8 9


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Another example What about the RMS amplitude of this sound wave?

It looks like this (in Excel):

pressure 1 1 1 -1 -1 -1 1 1 1

sample 1 2 3 4 5 6 7 8 9


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More Complex Waveforms The following waveforms all have the same peak-to-peak

amplitude:


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Intensity

Two related concepts are acoustic powerand intensity.

Poweris 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.


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Some Numbers The intensity of a sound x can be measured in bels,

where a bel is defined as:= log10 (x

2 / 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


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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


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Intensity Interactions

Perceived loudness depends on frequency, as well asamplitude.

Mid-range frequencies sound louder than low or extremely

high frequencies.

100 Hz

250 Hz

440 Hz

1000 Hz

4000 Hz

10000 Hz


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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] : -12.3

Why?


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Another Interesting Fact

Some vowels are inherently longer than others.

Data from Swedish (Elert, 1964):

long shorthigh [i y u] 140 msec 95

mid 155 103

low 164 111

Why?


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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.


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From Ladefoged


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A Sonority Scale

low vowels

high vowelsglides

liquids

nasals

fricatives

stops

high sonority

low sonority


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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: [bd] is a well-formed syllable in English.

[]

[b] [d]

high sonority

low sonority


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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: [blnd] works well, too.

[]

[l] [n]

[b] [d]

high sonority

low sonority


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Technical Terms

[]

[l] [n]

[b] [d]

high sonority

low sonority

sonority peak


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Technical Terms

The sonority peak forms the nucleus of the syllable.

[]

[l] [n]

[b] [d]

high sonority

low sonority

nucleus


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Technical Terms


The sounds that precede the nucleus form the syllable onset.

[]

[l] [n]

[b] [d]

high sonority

low sonority

onset


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Technical Terms



The sounds that follow the nucleus form the syllable coda.

[]

[l] [n]

[b] [d]

high sonority

low sonority

coda


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Technical Terms The sonority peak forms the nucleus of the syllable.


The sounds that follow the nucleus form the syllable coda.

Together, the nucleus and coda form the syllable rhyme.

[]

[l] [n]

[b] [d]

high sonority

low sonority

rhyme


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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 snowsweet

What onset clusters should be ruled out?

Can you think of any English examples where this

principle might not work?


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Some basic principles Codas must drop in sonority away from the syllable peak.

Examples:

nasal - {fricative/stop} tenthhand

liquid - {fricative/nasal/stop} help helmheart

fricative - stop test

What coda clusters should be ruled out?

Can you think of any English examples where this

principle might not work?


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Other ProblemsThe Sonority Sequencing Principle doesnt always work.

How can we define a syllable?

An alternative idea: each syllable is a chest pulse

(Stetson, 1951)

It turns out this doesnt work, either.

Chest muscles dont necessarily contract for each

syllable (Ladefoged, 1967)

Any better ideas?

12 syllables and stress

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