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Anatomy and physiology of human respiration and phonation

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									Anatomy and physiology of human respiration and phonation
Paper Li9 Foundations of Speech Communication Rachel Smith October 14 2005

Aims
1. To outline principles of muscle behaviour and speech anatomy and physiology, with main focus on breath control and phonation 2. To explore consequences of these principles for aspects of linguistic form

Control of muscles in the body
• Muscles are made up of lots of fibres, each one of which has its own nerve endings • A muscle fibre contracts when the neuron (single nerve fibre) that innervates it fires; and relaxes when the neuron stops firing • Muscle fibres in a single muscle are organised into groups (motor units) each innervated by a single neuron Nerve fires once  motor unit twitches once Faster firing  more continuous (tetanic) contraction Too much firing for too long  cramp-like state

Using muscles to move parts of the body
• For most voluntary movement, muscles move one part of the body relative to another because each muscle is attached to two different solid structures, e.g. two bones, across a joint.
– origin of muscle is on one bone (usually stays fixed during contraction) – insertion is on the other (usually moves)

3 types of movement
1. Movements of fixation
– opposing groups of muscles (agonistic and antagonistic) hold a part of the body in position
 2 opposing muscle groups work in synergy the movement consists of a single contraction of the agonist muscle group, with the antagonist group(s) relaxed. It is impossible to change the course of the movement once it is started. The antagonist group(s) normally contracts to terminate it.

2. Controlled movements
– –

3. Ballistic movements

The respiratory pump
• The spongy lungs can be likened to two balloons that are inflated and deflated as if by a bicycle pump. • The basis for the action of the respiratory pump is the way the lungs are linked to the ribcage (thoracic cavity) and abdomen by two pleurae (membranes). A layer of fluid between the pleurae allows them to move freely and provides suction to maintain the linkage. • The consequence of the linkage is that the lungs expand and contract as the ribcage and abdomen move around
EI
R abdominal muscles led by Rectus abdominus D diaphragm

II D R

EI external intercostal muscles II internal intercostal muscles

The respiratory pump
1. Because volume and pressure are related, altering the lung volume changes the air pressure in the lungs (Pa, Psg)
– Increasing lung volume (e.g. by pushing the ribcage or abdomen outwards) lowers air pressure Decreasing lung volume raises air pressure
pressure

EI
R abdominal muscles led by rectus abdominus D diaphragm

II D R

–

EI external intercostal muscles II internal intercostal muscles

volume

The respiratory pump
2. Air flows from regions of higher to lower pressure, so air flows into the lungs when pressure decreases below atmospheric level, and out when pressure increases above atmospheric level
pressure

EI
R abdominal muscles led by rectus abdominus D diaphragm

II D R

EI external intercostal muscles II internal intercostal muscles

volume

The respiratory pump
3. INspiration (breathing IN) normally involves muscular effort: contracting EXternal intercostal muscles (to elevate ribs) and diaphragm (which lowers as it contracts, expanding volume of thorax).
EI
R abdominal muscles led by rectus abdominus D diaphragm

II D R

EI external intercostal muscles II internal intercostal muscles

The respiratory pump
4. EXpiration (breathing out) can use muscular control (mainly contraction of INternal intercostal muscles). But in quiet breathing, expiration is normally passive: the elastic recoil of the lungs does most of the work.
EI
R abdominal muscles led by rectus abdominus D diaphragm

II D R

EI external intercostal muscles II internal intercostal muscles

Some terminology
Total lung capacity Insp. reserve volume Vital capacity Resting tidal volume (TV) TV during activity

Exp. reserve volume

Residual volume

Breathing for speech
1. Speech requires much more muscular control than quiet breathing, to sustain the correct pressure over the long vocalisations that humans typically produce. Without adequate breath control, the air goes out too fast.
-60 -30 0 30 60

% vital capacity

100 ‘relaxation pressure’ (no muscular effort)

pressure needed for utterance

0

alveolar pressure (cm H2O)

Breathing for speech
1. Speech requires much more muscular control than quiet breathing, to sustain the correct pressure over the long vocalisations that humans typically produce. Without adequate breath control, the air goes out too fast.
-60 -30 0 30 60

100

‘relaxation pressure’ (no muscular effort)

pressure needed for utterance

Shaded blue areas: amount of extra contribution from muscular effort needed to sustain correct pressures over utterance

% vital capacity 0

alveolar pressure (cm H2O)

Breathing for speech
2. Therefore: • At the start of an utterance, the flow of air out of the lungs is braked by using the inspiratory muscles (external intercostals and/or diaphragm) to keep lung volume high • Once the resting expiratory volume has been reached, the expiratory muscles (internal intercostals) are used to push more air out until the end of the utterance.
-60 -30 0 30 60

% vital capacity

‘relaxation pressure’

utterance

alveolar pressure (cm H2O) % vital capacity muscular pressure (cm H2O): inspiratory expiratory

Differences between speech breathing and life breathing
• Young children’s lungs are smaller than adults’. Their airways are also more resistant to airflow. But they need to generate approximately the same airflows as adults do. Therefore, they need more muscular effort (esp. expiratory) to achieve the right pressure. Consequences e.g. shorter breath groups. • Neuropathology can affect breathing for speech: e.g. trying to impose metabolic breathing on speech; sufferers from anarthria sometimes take a breath between each word

Structure of the larynx
• 3 main cartilages:
– large, semicircular thyroid (Adam’s apple) (connected upwards to hyoid bone by thyrohyoid muscle/ligament – smaller, solid cricoid with ‘signet ring’ shape: higher at back than front – 2 small, pyramid-shaped arytenoids sitting on top of posterior surface of cricoid

• Vocal folds connect vocal process of arytenoids to inner front of thyroid cartilage

Front view

Rear view

Side view

View from top

Vertical structure of the vocal folds during one vibratory cycle
The folds are threedimensional, and they vibrate in three dimensions. The pattern of vibration is like a ‘wave’ travelling up them. The lower sections part first, and come together first. 2 5 ‘Cover’ (outer layers) and ‘body’ (inner layers) of folds are often distinguished. 3 6 After Stevens (1998) Acoustic Phonetics

1

4

Starting and stopping voicing
voicing in stops: differences in voice onset time (VOT)
clo rel

clo = closure
rel = release = voicing = voicelessness

[ɑtʰɑ] voiceless aspirated
clo rel

[ɑtɑ] voiceless unaspirated
clo rel

[ɑdɑ] voiced

Starting and stopping voicing

Front view

Rear view

Side view

• Abduction: arytenoids rotated backwards and apart (posterior cricoarytenoid muscle) • Adduction: arytenoids moved together (interarytenoid, lateral cricoarytenoid muscles)

Starting and stopping voicing

Front view

Rear view

Side view

• Abduction: arytenoids rotated backwards and apart (posterior cricoarytenoid muscle) • Adduction: arytenoids moved together (interarytenoid, lateral cricoarytenoid muscles)

Starting and stopping voicing

Front view

Rear view

Side view

• Abduction: arytenoids rotated backwards and apart (posterior cricoarytenoid muscle) • Adduction: arytenoids moved together (interarytenoid, lateral cricoarytenoid muscles)

Starting and stopping voicing

Front view

Rear view

Side view

• Abduction: arytenoids rotated backwards and apart (posterior cricoarytenoid muscle) • Adduction: arytenoids moved together (interarytenoid, lateral cricoarytenoid muscles)

Pitch control

Front view

Rear view

Side view

• Increasing pitch: contracting cricothyroid muscle: pulls front of cricoid up towards thyroid, so back of cricoid moves down and back, taking arytenoids with it and stretching/tensing vfs  vibrate faster • vocalis – shortens and tenses vocal folds

Pitch control

Front view

Rear view

Side view

• Increasing pitch: contracting cricothyroid muscle: pulls front of cricoid up towards thyroid, so back of cricoid moves down and back, taking arytenoids with it and stretching/tensing vfs  vibrate faster • vocalis – shortens and tenses vocal folds

Pitch control

Front view

Rear view

Side view

• Increasing pitch: contracting cricothyroid muscle: pulls front of cricoid up towards thyroid, so back of cricoid moves down and back, taking arytenoids with it and stretching/tensing vfs  vibrate faster • vocalis – shortens and tenses vocal folds

How does breath control and help to shape the prosody of speech?

Prosody in speech
• Commonly used to refer to a range of phonetic features, such as pitch, loudness, tempo, and rhythm.

• To describe the prosody of speech, we need to think about levels of organisation larger than the phonetic segment, e.g.
– syllable – foot

Syllable structure
Syllable (σ) Syllable (σ)

Onset

Rhyme

Onset

Rhyme

Nucleus

Coda

Nucleus

Coda









 

Foot structure
Accent group

Foot

Foot

σ strong

σ weak

σ strong

not

to-

day

Stress and focus
• Different kinds of prominence borne by syllables: • Lexical stress e.g. below [] vs. billow []

• Sentence stress (focus)
a) (Does Deb love Bob?) No, BEV loves Bob b) (Does Bev love Rob?) No, Bev loves BOB

What is the respiratory contribution to speech prosody?
A separate muscular contraction for every syllable? Classic work by Stetson (1951) proposed that: 1. The syllable is constituted by a ballistic movement of the intercostal muscles. 2. This movement is terminated either by a consonant constriction (which checks airflow) or by contracting the inspiratory muscles 3. Longer-term prosodic units (foot, breath group) are defined by contractions of the abdominal muscles.

What is the respiratory contribution to speech prosody?
• • Pressure, flow and movement data seemed to support Stetson’s view. But work in the 1950s using electromyography and other techniques (e.g. Draper, Ladefoged and Whitteridge 1959, Ladefoged 1967) discredited it. They argued that the respiratory system contributes to stress, but does not define syllables. Others proposed a role for the laryngeal muscles in regulating intensity (loudness – an important part of stress).

•

•

What is the respiratory contribution to defining speech prosody?
• • But DLW’s results are also in question now. Finnegan et al. (2000) measured tracheal pressure, laryngeal muscle activity, and airflow. They showed that the respiratory system contributes much more than laryngeal muscle activity to both short-term and long-term changes in intensity.

•

What is the respiratory contribution to defining speech prosody?
• Messum (2003) returns to an account like Stetson’s, but based around the foot rather than the syllable (for stress-timed languages like English and German). On his account, each foot is produced by a single, invariant pulse of effort from the muscles of the chest. Speculative, but promising…

Example
…because it could go some way to explaining why other phonetic properties pattern in the way they do e.g. tense and lax vowels in English:
• only tense vowels can occur in open syllables e.g. English / iː ɔː ɑː uː / as in bee bore bar boo (They can also occur in closed syllables e.g. bead) lax vowels can only occur in closed syllables e.g. English / ɪ ɛ æ ɒ ʌ ʊ / as in bid bed bad bod bud Buddha

•

•

…perhaps because lax vowels involve a greater airflow than tense ones, so the air would be lost too fast if the airflow wasn’t checked by a consonant?

Reading
Suggested reading • LIEBERMAN, P. and BLUMSTEIN, S.E. (1988) Speech Physiology, Speech Perception, and Acoustic Phonetics. Cambridge: Cambridge University Press. Chapters 2 and 6. • CLARK, J., and YALLOP, C. (1995/1990). Phonetics and Phonology. Oxford: Blackwell. (2nd/1st ed.) Chapter 2 (1990 edition) or Chapters 2 and 6 (1995 edition). • LAVER, J. (1994). Principles of Phonetics. Cambridge: CUP. Chapters 6 & 7. Advanced reading • KELSO, J.A.S. and MUNHALL, K.G. (eds.) (1988). R.H. Stetson’s Motor Phonetics: A Retrospective Edition. Ch.3. • LADEFOGED, P. (1967). Three Areas of Experimental Phonetics. Ch. 1. • MESSUM, P. (2003). Invariance of effort in child speech breathing as a ‘fast and frugal’ heuristic for the acquisition of phonetic phenomena in stress-accent languages. Proceedings of ICPhS 2003, Barcelona. [RB] • HIXON, T.J. (1987). Respiratory Function in Speech and Song. London: Taylor and Francis. [UL 303:2.c.95.1420]. Ch.1 only. Also published as MINIFIE, F.D., HIXON, T.J., & WILLIAMS, F. (eds.) (1973). Normal Aspects of Speech, Hearing, and Language. Englewood Cliffs, NJ: Prentice-Hall Inc. Chapter 3 (Hixon). [Detailed, dry.]

Anatomy colouring books • KAPIT, W. and ELSON, L.M. (2002/1993/1977). The Anatomy Coloring Book (3rd/2nd/1st edition). [Photocopy relevant pages e.g. larynx, pharynx, tongue, face, structure of muscle, nervous system, and colour them in!] [RB]


								
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