open-air

Examples of open-air in the following topics:

• Sound Production: Vibrating String and Air Columns

  • They are either open at both ends, or closed at one end and open at the other.
  • Lets start with the tubes that are closed at one end and open at the other.
  • Closed Air Tubes:The maximum displacement of the air occurs at the open end of the tube, and is called the antinode.
  • Open Air tubes:Air tubes can also be open at both ends.
  • All have maximum air displacements at the open end and none at the closed end.

• Standing Waves in Air Columns

  • When a standing wave is formed in a tube, the standing wave has a maximum air displacement at the open end called an antinode.
  • Given that maximum air displacements are possible at the open end and none at the closed end, there are other, shorter wavelengths that can resonate in the tube.
  • Here, f is frequency, vw is speed of sound in air, λ is wavelength, and L is the length of the air column.
  • All have maximum air displacements at the open end and none at the closed end.
  • Identify the type of a standing wave in an air column

• Factors Affecting Pulmonary Ventilation: Airway Resistance

  • Airway resistance is the resistance to flow of air caused by friction with the airways, which includes the conducting zone for air, such as the trachea, bronchi and bronchioles.
  • Therefore the resistance to air in the bronchi is greater than the resistance to air in the trachea.
  • The number of airways also plays a large role in the resistance to air, with more airways reducing resistance because there are more paths for the air to flow into.
  • Emphysema also increases airway resistance because the lung tissue becomes too pliable and it the airways become more difficult to hold open by the flow of air.
  • The air that flows through the lungs varies considerably in the properties of the flow of air.

• Types of Breathing

  • During exhalation, the lungs expel air and lung volume decreases.
  • As the diaphragm relaxes, air passively leaves the lungs .
  • Air flows in one direction from the posterior air sacs to the lungs and out of the anterior air sacs.
  • This directionality of airflow requires two cycles of air intake and exhalation to completely remove the air from the lungs .
  • The air sacs connect to openings in hollow bones.

• Mammalian Systems and Protective Mechanisms

  • As air crosses the surfaces of the mucous membranes, it picks up water.
  • This equilibrates the air to the body, reducing damage that cold, dry air can cause.
  • Particulates in the air are also removed in the nasal passages.
  • The function of the trachea is to funnel the inhaled air to the lungs and the exhaled air out of the body.
  • The cartilage provides strength and support to the trachea to keep the passage open.

• Inspiration

  • Inhalation is the flow of air into an organism which is generated due to pressure difference between the atmosphere and alveolus.
  • In humans it is the movement of ambient air through the airways, and into the alveoli of the lungs.
  • Pressure and volume are inversely related to eachother, so the drop in pressure inside the lung increases the volume of air inside the lung by drawing outside air into the lung.
  • The force of the intrapleural pressure is even enough to hold the lungs open during inpiration despite the natural elastic recoil of the lung.
  • For example,  singers need a lot of air to support the powerful voice production in singing.

• Trachea

  • The trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air.
  • The trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air.
  • The trachea is part of the conducting zone for air into and out of the lungs.
  • The trachealis muscle connects the open ends of the C-shaped rings of cartilage and contracts during coughing, reducing the size of the lumen of the trachea to increase the air flow rate.
  • The epiglottis closes the opening to the larynx during swallowing to prevent swallowed matter from entering the trachea.

• Structures Used in Voice Production

  • Voices produce sounds through a steady flow of air through the larynx, which causes vibrations and creates fluctuations in air pressure.
  • Air Supply: In order for voice to be produced, air must flow through the vocal folds.
  • The speed of air flow also determines the strength and loudness of the voice.
  • Vowels are articulated sounds that do not come from obstruction, and instead come from an open vocal tract.
  • A vowel is a sound that comes from an open vocal tract, and does involve strict obstruction of the sound as with consonants.

• The Mechanics of Human Breathing

  • The thoracic cavity, or chest cavity, always has a slight, negative pressure which aids in keeping the airways of the lungs open.
  • This pressure gradient between the atmosphere and the thoracic cavity allows air to rush into the lungs; inhalation occurs.
  • Upon exhalation, the lungs recoil to force the air out of the lungs.
  • Air rushes out of the lungs due to the pressure gradient between the thoracic cavity and the atmosphere.
  • This movement of air out of the lungs is classified as a passive event since there are no muscles contracting to expel the air.

• Standing Waves in Wind Instruments

  • The string disturbs the air molecules around it as it vibrates, producing sound waves in the air.
  • But another great container for standing waves actually holds standing waves of air inside a long, narrow tube.
  • The standing-wave tube of a wind instrument also may be open at both ends, or it may be closed at one end (for a mouthpiece, for example), and this also affects the instrument.
  • Standing Waves in a wind instrument are usually shown as displacement waves, with nodes at closed ends where the air cannot move back-and-forth.
  • Here the displacement standing waves in Figure 3.10 are shown instead as longitudinal air pressure waves.