HearingHearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory science. Sound may be heard through solid, liquid, or gaseous matter. It is one of the traditional five senses. Partial or total inability to hear is called hearing loss.
Eustachian tubeIn anatomy, the Eustachian tube (juːˈsteɪʃən), also called the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. In adult humans, the Eustachian tube is approximately long and in diameter. It is named after the sixteenth-century Italian anatomist Bartolomeo Eustachi. In humans and other tetrapods, both the middle ear and the ear canal are normally filled with air.
Organ of CortiThe organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea. This highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential. Transduction occurs through vibrations of structures in the inner ear causing displacement of cochlear fluid and movement of hair cells at the organ of Corti to produce electrochemical signals. Italian anatomist Alfonso Giacomo Gaspare Corti (1822–1876) discovered the organ of Corti in 1851.
CholesteatomaCholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of their erosive and expansile properties. This can result in the destruction of the bones of the middle ear (ossicles), as well as growth through the base of the skull into the brain. They often become infected and can result in chronically draining ears.
Sensorineural hearing lossSensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve (cranial nerve VIII). SNHL accounts for about 90% of reported hearing loss . SNHL is usually permanent and can be mild, moderate, severe, profound, or total. Various other descriptors can be used depending on the shape of the audiogram, such as high frequency, low frequency, U-shaped, notched, peaked, or flat.
Auditory systemThe auditory system is the sensory system for the sense of hearing. It includes both the sensory organs (the ears) and the auditory parts of the sensory system. The outer ear funnels sound vibrations to the eardrum, increasing the sound pressure in the middle frequency range. The middle-ear ossicles further amplify the vibration pressure roughly 20 times. The base of the stapes couples vibrations into the cochlea via the oval window, which vibrates the perilymph liquid (present throughout the inner ear) and causes the round window to bulb out as the oval window bulges in.
Inner earThe inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts: The cochlea, dedicated to hearing; converting sound pressure patterns from the outer ear into electrochemical impulses which are passed on to the brain via the auditory nerve.
OtotoxicityOtotoxicity is the property of being toxic to the ear (oto-), specifically the cochlea or auditory nerve and sometimes the vestibular system, for example, as a side effect of a drug. The effects of ototoxicity can be reversible and temporary, or irreversible and permanent. It has been recognized since the 19th century. There are many well-known ototoxic drugs used in clinical situations, and they are prescribed, despite the risk of hearing disorders, for very serious health conditions.
Sense of balanceThe sense of balance or equilibrioception is the perception of balance and spatial orientation. It helps prevent humans and nonhuman animals from falling over when standing or moving. Equilibrioception is the result of a number of sensory systems working together; the eyes (visual system), the inner ears (vestibular system), and the body's sense of where it is in space (proprioception) ideally need to be intact. The vestibular system, the region of the inner ear where three semicircular canals converge, works with the visual system to keep objects in focus when the head is moving.
OssiclesThe ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss. The term "ossicle" literally means "tiny bone". Though the term may refer to any small bone throughout the body, it typically refers to the malleus, incus, and stapes (hammer, anvil, and stirrup) of the middle ear.
Middle earThe middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear is also known as the tympanic cavity and is surrounded by the tympanic part of the temporal bone.
Outer earThe outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal. It gathers sound energy and focuses it on the eardrum (tympanic membrane). Auricle (anatomy) The visible part is called the auricle, also known as the pinna, especially in other animals. It is composed of a thin plate of yellow elastic cartilage, covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the ear canal by fibrous tissue.
Hearing aidA hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers such as personal sound amplification products (PSAPs) or other plain sound reinforcing systems cannot be sold as "hearing aids". Early devices, such as ear trumpets or ear horns, were passive amplification cones designed to gather sound energy and direct it into the ear canal.
OtorhinolaryngologyOtorhinolaryngology (oʊtoʊˌraɪnoʊˌlærɪnˈgɒlədʒi , abbreviated ORL and also known as otolaryngology, otolaryngology – head and neck surgery (ORL–H&N or OHNS), or ear, nose, and throat (ENT) is a surgical subspeciality within medicine that deals with the surgical and medical management of conditions of the head and neck. Doctors who specialize in this area are called otorhinolaryngologists, otolaryngologists, head and neck surgeons, or ENT surgeons or physicians.
Otitis mediaOtitis media is a group of inflammatory diseases of the middle ear. One of the two main types is acute otitis media (AOM), an infection of rapid onset that usually presents with ear pain. In young children this may result in pulling at the ear, increased crying, and poor sleep. Decreased eating and a fever may also be present. The other main type is otitis media with effusion (OME), typically not associated with symptoms, although occasionally a feeling of fullness is described; it is defined as the presence of non-infectious fluid in the middle ear which may persist for weeks or months often after an episode of acute otitis media.
Valsalva maneuverThe Valsalva maneuver is performed by a forceful attempt of exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut while expelling air out as if blowing up a balloon. Variations of the maneuver can be used either in medical examination as a test of cardiac function and autonomic nervous control of the heart, or to clear the ears and sinuses (that is, to equalize pressure between them) when ambient pressure changes, as in scuba diving, hyperbaric oxygen therapy, or air travel.
Auricle (anatomy)The auricle or auricula is the visible part of the ear that is outside the head. It is also called the pinna (Latin for "wing" or "fin", plural pinnae), a term that is used more in zoology.
SoundIn physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans.
Cochlear implantA cochlear implant (CI) is a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception. With the help of therapy, cochlear implants may allow for improved speech understanding in both quiet and noisy environments. A CI bypasses acoustic hearing by direct electrical stimulation of the auditory nerve. Through everyday listening and auditory training, cochlear implants allow both children and adults to learn to interpret those signals as speech and sound.
Sound localizationSound localization is a listener's ability to identify the location or origin of a detected sound in direction and distance. The sound localization mechanisms of the mammalian auditory system have been extensively studied. The auditory system uses several cues for sound source localization, including time difference and level difference (or intensity difference) between the ears, and spectral information.
