Respiration + Pulmonic Airflow

1. Respiration + Pulmonic Airflow February 4, 2014 These notes are largely adapted from Thomas J. Hixon (1973), “Respiratory Function in Speech”, in Normal Aspects of Speech, Hearing and Language.

2. Taking Care of Business • Production exercises are due on Thursday; • A second one will be sent out afterwards. • Today: • Respiration first • then maybe Phonation • Okay. Everybody take a deep breath!

3. From the Bottom Up • All speech sounds require airflow. • The vast majority of sounds in the world’s languages use a pulmonic egressive airflow. • = out of the lungs • Questions to answer/consider: • How do we make air flow out of the lungs? • How does pulmonic airflow differ in breathing and in speech? • How does pulmonic airflow relate to language? • primarily: suprasegmentals (stress, F0)

4. The Machinery • The human torso (from the neck to the legs) has two major divisions: • The thorax • consisting of the heart and lungs • the “chest” • The abdomen • includes the digestive system and other interesting glands • the “belly”

5. The Thorax • The heart and the pulmonary system are enclosed by the thoracic cage. • the “rib cage” • Ribs are connected by cartilage to the sternum. • The intercostal muscles fill in the gaps between ribs... • and also cover the surfaces of the thoracic cage.

6. Connections • The thorax is split from the abdomen by a dome-shaped structure known as the diaphragm. • The lungs sit on top of the diaphragm. • Two membranes link the lungs to the ribs: • The visceral pleura covers the lungs. • The parietal pleura lines the inside of the thoracic cage.

7. Equilibrium • The linkage between the lungs and the rib cage makes: • The lungs are bigger than they would be on their own. • The rib cage is smaller than it would be on its own. • The linkage tends towards a natural equilibrium point. volume

8. Taking A Step Back • Air flows naturally from areas of high pressure to areas of low pressure. • Q: How do we make air pressure differences? • A: We take advantage of Boyle’s Law. • Boyle’s Law states that: • the pressure of the gas in a chamber is inversely proportional to the volume of gas in the chamber •  The pressure of the gas can be increased or decreased by changing the volume of the chamber. • decreasing volume  increases pressure • increasing volume  decreases pressure

9. Inspiration • A normal breathing cycle begins with inspiration • “breathing in” • Air will flow into the lungs if... • the air pressure inside the lungs is lower than it is outside the lungs • Air pressure can be decreased inside the lungs by... • expanding the volume of the lungs. • Lung volume can be expanded: • In all three dimensions • With two primary muscle mechanisms

10. Expansion #1 • The vertical expansion of the thorax is primarily driven by the contraction of the muscles in the diaphragm. • This bows out the front wall of the abdomen. • Also: diaphragm contraction elevates the lower ribs. •  expands the circumference of the thorax.

11. Expansion #2 • The thorax can also be expanded through the contraction of the external intercostal muscles. • Contraction of each intercostal muscle lifts up the rib beneath it. • Also pulls each rib forward with the sternum. • = expansion in the front-back dimension. sternum

12. Expansion #3 • The thorax can also be expanded through the contraction of the external intercostal muscles. • Contraction of the intercostals elevates the lower ribs more than the upper ribs • Lower ribs lift like a “bucket handle” • Expansion in the side-to-side dimension.

13. Expiration • Air flows out of the lungs whenever air pressure in the lungs is greater than external air pressure. • Note: technical term • alveolar pressure = air pressure inside the lungs • Alveolar pressure may be increased by decreasing lung volume. • Lung volume is decreased through both passive and active forces. • Normally, lungs contract after inspiration due to passive forces alone. • No muscular effort is necessary!

14. Passive Expiration • Thorax + lungs combo contracts back to its equilibrium point without any external impetus. • Relaxation pressure is inherent pressure on the lungs to revert back to the equilibrium point. • Note: relaxation pressure works both ways.

15. Active Expiration • Lung volume can be actively decreased by contracting a variety of muscles which: • Lower the ribs and/or sternum • thereby compressing the thorax in the front-to-back and side-to-side dimensions • Increase abdominal pressure • thereby driving the diaphragm upwards

16. Expiration #1 • The thoracic cage can be compressed by contracting the internal intercostals and the transversus thoracis. • These pull the ribs downward... • effectively the opposite action of contracting the external intercostals.

17. Expiration #2 • The most important muscles for active expiration increase pressure in the abdomen. • These include the rectus abdominis, the external and internal obliques, and the transversus abdominis. • Contracting these muscles drives in the abdomen... • and pulls down the sternum and lower ribs.