Infrasound refers to sound waves below 20 Hz that cannot be heard by humans but can be felt. It can produce anxiety, sorrow, or chills in people and carries far distances with little loss of strength. Examples of natural infrasound sources include volcanoes, earthquakes, and ocean waves. Ultrasound refers to sound waves above 20 kHz that cannot be heard but can be used in medical imaging devices to produce images of internal tissues and structures. Ultrasound works by transmitting sound waves that bounce off internal tissues and are received back by the transducer to form an image. It is used for fetal imaging, cardiac imaging, and assessing blood flow through Doppler techniques.
Sound is composed of compression and rarefaction waves that the human ear can detect. It is produced by vibrations that create pressure variations in a medium and can be caused by either simple or complex motions. Sound waves carry energy and are longitudinal waves where the size of the compression indicates the energy. The human ear detects sound waves through the vibration of the ear drum which are then amplified by the bones and converted to nerve impulses in the cochlea. Properties of sound waves include pitch determined by frequency, loudness by amplitude, and timbre which distinguishes between sounds of the same pitch and loudness.
The document discusses different aspects of sound including how it is produced, how it travels, and how the human ear perceives it. It defines sound as a mechanical wave that is an oscillation of pressure transmitted through a medium composed of frequencies within the range of human hearing. It describes that sound is produced by vibration and travels in waves, pushing and pulling on particles in the transmission medium. The human ear detects these pressure variations and converts them into electrical signals that are sent to the brain.
A wave is a repeating disturbance that transfers energy through matter or space. There are two main types of waves - longitudinal waves, where the matter moves parallel to the direction of the wave, and transverse waves, where energy is transferred without transferring matter. Sound is a form of energy caused by vibrations that transfers through longitudinal waves. Key properties of waves include wavelength, frequency, amplitude, and speed. Sound waves can interfere constructively or destructively and be reflected, refracted, or absorbed.
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