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Topic 3c: Respiration

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Learning Objectives• Posses a knowledge of respiratory anatomy sufficient to understand

basic respiratory physiology and its relation to speech sound generation.

• Describe how physical laws help explain how air is moved in and out of the body

• Outline the functional subdivisions of the lung volume space• Compare and contrast characteristics of speech breathing and

metabolic/vegetative breathing• Use the pressure-relaxation curve to explain the active and passive

forces involved in controlling the respiratory system• Describe how various respiratory impairments can lead to

diminished speech production abilities

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Learning Objectives

• Posses a knowledge of respiratory anatomy sufficient to understand basic respiratory physiology and its relation to speech sound generation.

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• Why do we breathe?

• How does breathing help us speak?

Speech Breathing

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• Primary functional goal

• Surface features

• Mechanisms underlying action

Life and Speech Breathing ARE DISTINCT PROCESSES in terms

of

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Role of breathing in speech

• Respiratory System is a Variable Power Source• Aerodynamic power needed to generate sound

sources– Phonation, frication, bursts, aspiration

• Must be able to vary power to allow for– Intensity variation (phonation & obstruent production)– Fundamental frequency variation

• Must also meet metabolic needs of speaker

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Structure and Mechanics of Respiratory System

• Pulmonary system– Lungs and airways

• Upper respiratory system• Lower respiratory system

• Chest wall system– “Houses” pulmonary system– Structures on which muscle activity is generated

• Pulmonary system & chest wall are linked (pleural linkage)

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Pulmonary system: lower respiratory tract

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Pulmonary system: lower respiratory tract

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Chest wall system

• Rib cage

• Abdomen

• Diaphragm

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Chest wall-Lung relation

• Lungs not physically attached to the thoracic walls• Lungs: visceral pleura• Thoracic wall: parietal pleura• Filled with Pleural fluid

• Ppleural < Patm - “pleural linkage” allows the lungs to move with the thoracic wall

• Breaking pleural linkage Ppleural = Patm - pneumothorax

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Thorax

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Abdomen

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Diaphragm

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Learning Objectives

• Describe how physical laws help explain how air is moved in and out of the body

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Physics of Breathing

Key Quantities• Pressure (P)• Volume (V)• Flow (U)

Boyle’s Law

• V=k/P or V P=k• As V ↑ P↓• As V ↓ P ↑

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Flow (U)

A B

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Moving air within respiratory system

Vthoracic = Palv

Palv < Patm (- Palv)

P differential = density differential air molecules flowing into lungs = inspiration

Vthoracic = Palv

Palv > Patmos (+ Palv)

P differential = density differential air molecules flow out of lungs = expiration

Patm: atmospheric pressure Palv: alveolar pressure* Vthoracic : thoracic volume

P = k/V: Boyle’s Law

*pressure in lungs typically described as alveolar pressure

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Changing thoracic volume (Vthoracic): two degree of freedom model

Requires• Muscular forces• Elastic forces

Strategies• ∆ Length• ∆ Circumference

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Changing length of thoracic cavity

Diaphragm

Abdominal wallmuscles

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Changing circumference of thoracic cavity

Rib cage elevation(e.g. external intercostals m.)

Rib cage lowering(e.g. internal intercostals m.)

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Summary: Changing lung volume ( Vlung)

• pleural linkage: Vthoracic = Vlung

Vthoracic is– raising/lowering the ribs (circumference)

• Raising: Vthoracic = inspiration

• Lowering: Vthoracic =expiration

– Raising/lowering the diaphragm (vertical dimension)• Raising: Vthoracic =expiration

• Lowering: Vthoracic =inspiration

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Learning Objectives

• Outline the functional subdivisions of the lung volume space

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Measuring Lung Volume: Spirometry

Lu

ng

Vo

lum

e

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Measuring Lung Volume: Spirometry

Time

Lun

g V

olum

e

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Selected volumes, capacities and levels

Tidal Volume (TV)– Volume of air inspired/expired during rest breathing.

Expiratory Reserve Volume (ERV)– Volume of air that can be forcefully exhaled, “below” tidal volume.

Inspiratory Reserve Volume (IRV)– Volume of air that can be inhaled, “above” tidal volume.

Vital Capacity (VC)– Volume of air that can be inhaled/exhaled (i.e. VC=IRV +TV+ERV)

Residual Volume (RV)– Volume of air left after maximal expiration. Measurable, but not easily so.

Total Lung Capacity (TLC)– Volume of air enclosed in the respiratory system (i.e. TLC=RV+ERV+TV+IRV)

Resting End Expiratory Level (REL)– Location in lung volume space where tidal breathing typically ends (35-40 % VC in

upright position)

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NOTE

• Some authors use the term FRC (functional residual capacity) instead of REL (resting end-expiratory level)

• Behrman uses resting lung volume (RLV)

• Refers to equivalent “place” in the lung volume space

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Some typical adult values

Typical Volumes & Capacities

Vital Capacity (VC) 4-5 liters

Total Lung Capacity (TLC)~ one liter more than VC

Resting Tidal Volume (TV)~ 10 % VC

Resting expiratory end level (REL)

~ 35-40% VC when upright

Typical Rest Breathing Values

Respiratory rate12-15 breaths/minute

Alveolar Pressure Palv+/- 2 cm H20

Airflow~ 200 ml/sec

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Learning Objectives

• Compare and contrast characteristics of speech breathing and metabolic/vegetative breathing

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Speech vs. Life Breathing

Rest Breathing

Volume10 % VC at rest

Alveolar Pressure Palv +/- 2 cm H20

Average Airflow100-200 ml/sec

Ratio of inhalation to exhalation

~40/60 to 50/50

Speech Breathing

Volume20-25 % VC @ normal loudness (note this varies by utterance

length)40 % loud speechAlveolar Pressure Palv + 8-10 cm H20 on expiration

Average Airflow100-200 ml/sec

Ratio of inhalation to exhalation

~ 10/90

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Respiratory System Mechanics• It is spring-like (elastic)

• Elastic systems have an equilibrium point (rest position)

• What happens when you displace it from equilibrium?

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Learning Objectives

• Use the pressure-relaxation curve to explain the active and passive forces involved in controlling the respiratory system

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equilibrium Longer thanequilibrium

Displacement away from equilibrium

Restoring force back to equilibrium

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equilibriumShorter thanequilibrium

Displacement away from equilibrium

Restoring force back to equilibrium

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equilibriumShorter thanequilibrium

Longer thanequilibrium

Displacement away from equilibrium

Restoring force back to equilibrium

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RELLung VolumeBelow REL

Lung VolumeAbove REL

Displacement away from REL

Restoring force back to REL

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Is the respiratory system heavily or lightly damped?

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Respiratory Mechanics: Bellow’s Analogy

• Bellows volume = lung volume• Handles = respiratory muscles• Spring = elasticity of the respiratory system

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REL: Respiratory System Equilibrium

• No pushing or pulling on the handles ~ no exp. or insp. muscle activity

• Volume in bellows at rest ~ REL

• Patmos = Palv, therefore no airflow

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muscle force

muscle force

elastic force

pull handles outward from rest V increases ~ Palv decreases Inward air flow INSPIRATION

Shifting Lung Volume away from REL

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muscle force

muscle force

elastic force

push handles inward from rest V decreases ~ Palv increases outward air flow EXPIRATION

Shifting Lung Volume away from REL

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Respiratory Mechanics: Bellow’s Analogy

Forces acting on the bellows/lungs are due to • Elastic properties of the system

– Passive– Always present

• Muscle activity– Active– Under nervous system control (automatic or voluntary)

• Moving to a volume other than REL requires an external force– Muscle activity (inspiratory or expiratory)– Mechanical assistance (mechanical ventilator)

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Characteristics of System Elasticity

• Since elastic recoil forces will have the effect of exerting a pressure within the respiratory system, the effect is termed the relaxation pressure

• Magnitude of relaxation pressure is roughly proportionate to the amount of displacement from REL

• REL is expressed as a lung volume• This gives rise to a relaxation pressure curve

– Plots relaxation pressure (units Palv) as a function of lung volume

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Relaxation Pressure Curve (as in Behrman)

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Relaxation Pressure Curve(Our version)

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% Vital Capacity

40 0100

0

Alv

eola

r P

ress

ure

(cm

H20

)

20

40

60

-20

-40

-6080 60 20

relaxation pressure REL

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Breathing for Life: Inspiration

pulling handles outward with net inspiratory muscle activity

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Breathing for Life: Expiration

No muscle activity Recoil forces alone returns

volume to REL

50% Vital Capacity

40 0100

0

Alv

eola

r P

ress

ure

(cm

H20

)

20

40

60

-20

-40

-6080 60 20

relaxation pressure

10 %

~ 2 cm

Breathing for Life

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Respiratory demands of speech

• Conversational speech requires– Constant average alveolar pressure

• Generate subglottal and supraglottal pressures for sound production

– Ability to generate quick variations in pressure• Vary intensity• Vary fundamental frequency• For emphatic and syllabic stress, phonetic requirements etc

– Requires a respiration system OPTIMIZED for action

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Respiratory demands of speech

• Conversational speech – Volume solution

• Constant alveolar pressure 8-10 cm H20

– Pulsatile solution• Brief increases

above/below constant alveolar pressure

• Driving analogy– Volume solution

• Maintain a relatively constant speed

– Pulsatile solution• Brief

increases/decreases in speed due to moment to moment traffic conditions

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Example

Time

Pre

ssur

e w

rt a

tmos

pher

e

0

-5

5

10

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Breathing for Speech: Inspiration

pulling handles outward with net inspiratory muscle activity

Rate of volume change is greater than rest breathing

55% Vital Capacity

40 0100

0

Alv

eola

r P

ress

ure

(cm

H20

)

20

40

60

-20

-40

-6080 60 20

relaxation pressure

20 %

Target Palv ~ 8-10 cm

Breathing for Speech

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Breathing for Speech: Expiration

Expiratory muscle activity & recoil

forces returns volume to REL Pressure is net effect of expiratory

muscles (assisting) and recoil forces (assisting)

57% Vital Capacity

40 0100

0

Alv

eola

r P

ress

ure

(cm

H20

)

20

40

60

-20

-40

-6080 60 20

20 % VCchange

Target Palv ~ 8-10 cm

Optimal regionPrelax > 0assists Palv

Add Pexp to Meet Palv

Prelax: relaxation pressurePsg: target alveolar pressurePexp: net expiratory muscle pressurePinsp: net inspiratory muscle pressure

58% Vital Capacity

40 0100

0

Alv

eola

r P

ress

ure

(cm

H20

)

20

40

60

-20

-40

-6080 60 20

20 % VCchange

Target Palv ~ 8-10 cm

Optimal regionPrelax > 0assists Palv

Add Pexp to Meet Psg

Prelax: relaxation pressurePalv: target alveolar pressurePexp: net expiratory muscle pressurePinsp: net inspiratory muscle pressure

Below RELPrelax < 0opposes Palv

Add Pexp to meet Palv

& overcome

Prelax

Prelax > Palv

Requires “braking”Add Pinsp to Meet Palv

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Speech Breathing is VERY ACTIVE

• Modern view of speech breathing (Hixon et al. (1973, 1976)

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Summary: Muscle activityInspirationLife• Active inspiratory muscles

– Principally diaphragmSpeech• COACTIVATION OF

– inspiratory muscles• Diaphragm• Rib cage elevators

– expiratory muscles (specifically abdominal)

• INS > EXP = net inspiration• System ‘tuned’ for quick

inhalation

ExpirationLife• Relaxation pressure• No muscle activitySpeech• Active use of

– rib cage depressors– abdominal muscles

• System “Tuned” for quick brief changes in pressure to meet linguistic demands of speech

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Summary: Muscle activity

No AirflowLife• Minimal muscle

activitySpeech• COACTIVATION of

– Inspiratory: rib cage– Expiratory: abdomen– System ‘balanced’

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Interpretation of information

• Constant muscle activity may serve to “optimize” the system in various ways

For example,• Abdominal activity during inspiration• pushes on, and stretches the diaphragm• Optimal length-tension region of diaphragm• Increase ability for rapid contraction which is

needed for speech breathing

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Interpretation of information

• Constant muscle activity may serve to “optimize” the system in various ways

For example,• Abdominal activity during expiration• Provides a platform for rapid changes in ribcage

volume (pulsatile)• Without constant activity, abdomen would

‘absorb’ the forces produced by the ribcage

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Learning Objectives

• Describe how various respiratory impairments can lead to diminished speech production abilities

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Chest Wall Paralysis

• Remember those spinal nerves…• Paralysis of many muscles of respiration

Speech breathing features• variable depending on specific damage abdominal size during speech control during expiration resulting in difficulty

generating consistent Palv and modulating Palv

• Treatment: Support the abdomen

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Mechanical Ventilation

• Breaths are provided by a machineSpeech breathing features control over all aspects of breath support• Length of inspiratory/expiratory phase• Large, but inconsistent Palv

• Inspiration at linguistically inappropriate places• Speech breathing often occurs on inspiration• Treatment: “speaking valves”, ventilator

adjustment, behavioral training

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Parkinson’s Disease (PD)

• Rigidity, hypo (small) & brady (slow) kinesia

Speech breathing features muscular rigidity stiffness of rib cage abdominal involvement relative to rib cage ability to generate Palv

• modulation Palv

• Speech is soft and monotonous

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Cerebellar Disease

• dyscoordination, inappropriate scaling and timing of movements

Speech breathing features• Chest wall movements w/o changes in LV

(paradoxical movements) fine control of Palv

• Abnormal start and end LV (below REL)• speech has a robotic quality

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Other disorders that may affect speech breathing

• Voice disorders

• Hearing impairment

• Fluency disorders

• Motoneuron disease (ALS)

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Lifespan considerations (Kent, 1997)• Respiratory volumes and capacities

until young adulthood young adulthood to middle age during old age

stature elastic properties muscle mass

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Lifespan considerations (Kent, 1997)• Maximum Phonation Time (MPT)

– Longest time you can sustain a vowel– Function of

• Air volume• Efficiency of laryngeal valving

– Follows a similar pattern to respiratory volume and capacities

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Lifespan considerations (Kent, 1997)• Birth

– Respiration rate 30-80 breaths/minute– Evidence of ‘paradoxing’– Limited number of alveoli for oxygen

exchange

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Lifespan considerations (Kent, 1997)• 3 years

– Respiration rate 20-30 breaths/minute– Speech breathing characteristics developing

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Lifespan considerations (Kent, 1997)• 7 years

– Adult-like patterns– > subglottal pressure than adults– Number of alveoli reaching adult value of 300,000

• 10 years– Functional maturation achieved

• 12-18 years– Increases in lung capacities and volume