Physiology of Hearing
The process of hearing is how the ear converts external sound vibrations into nerve impulses sent to the brain, which are translated into sounds. When an item vibrates, such as a guitar string being plucked, pressure pulses of vibrating air molecules—better known as sound waves—are created. By identifying and evaluating various physical qualities of the waves, the ear can differentiate between various subjective components of a sound, such as its volume and pitch. Pitch, or the number of wavelengths that pass a particular place in a unit of time, is the impression of the frequency of sound waves. The unit of measurement for frequency is hertz or cycles per second. The full hearing range of sounds extends from around 20 to 20,000 hertz, at least for typical young ears. The human ear is most sensitive to and easily perceives frequencies of 1,000 to 4,000 hertz. Although other mammals can hear them, ultrasonic sound waves have an even higher frequency. Loudness is the perception of a sound’s loudness or the force that sound waves apply to the tympanic membrane. The pressure or intensity of the sound will increase with its amplitude or strength, which will also increase the volume of the sound. Decibels (dB), a measurement that describes the relative amplitude of a sound on a logarithmic scale, are used to measure and quantify sound intensity. In other words, a decibel is a unit for comparing the intensity of any given sound with a reference sound that is barely audible to the average human ear at a frequency within the range of the ear’s most sensitivity. The range of human hearing, measured in decibels, ranges from 0 dB, or a level that is almost inaudible, to about 130 dB, or the point at which sound becomes painful. The energy of a sound must go through three modifications before it can reach the central nervous system. The tympanic membrane and middle ear ossicles first vibrate as a result of the air vibrations. These then cause the fluid in the cochlea to vibrate. Last but not least, the fluid vibrations create waves that pass down the basilar membrane and excite the organ of Corti’s hair cells. These cells transform the sound waves into nerve impulses that are then transmitted by the cochlear nerve fibers to the brainstem, where they are relayed after undergoing considerable processing to the primary auditory area of the cerebral cortex, the brain’s hearing center. The listener doesn’t actually hear the sound until the nerve impulses get here.
Anatomy and Physiology of Human Ear
The area of biology known as anatomy is dedicated to the study of the composition and organization of living things. The structural organization of living things is the focus of the natural science field of anatomy. It is an old science with roots in the Paleolithic era. Given that these are the processes via which anatomy is produced, whether over short- and long-term timescales, comparative anatomy, evolutionary biology, and phylogeny are intrinsically linked to anatomy. A common pairing of related disciplines is anatomy and physiology, which examine the structure and operation of organisms and their components, respectively. One of the fundamental basic disciplines used in medicine is human anatomy.