Ear Canal: The narrow passage way that conducts the sound collected by the EAR AURICLE to the TYMPANIC MEMBRANE.Tympanic Membrane: An oval semitransparent membrane separating the external EAR CANAL from the tympanic cavity (EAR, MIDDLE). It contains three layers: the skin of the external ear canal; the core of radially and circularly arranged collagen fibers; and the MUCOSA of the middle ear.Ear: The hearing and equilibrium system of the body. It consists of three parts: the EXTERNAL EAR, the MIDDLE EAR, and the INNER EAR. Sound waves are transmitted through this organ where vibration is transduced to nerve signals that pass through the ACOUSTIC NERVE to the CENTRAL NERVOUS SYSTEM. The inner ear also contains the vestibular organ that maintains equilibrium by transducing signals to the VESTIBULAR NERVE.Ear, Middle: The space and structures directly internal to the TYMPANIC MEMBRANE and external to the inner ear (LABYRINTH). Its major components include the AUDITORY OSSICLES and the EUSTACHIAN TUBE that connects the cavity of middle ear (tympanic cavity) to the upper part of the throat.Otitis Externa: Inflammation of the OUTER EAR including the external EAR CANAL, cartilages of the auricle (EAR CARTILAGE), and the TYMPANIC MEMBRANE.Cerumen: The yellow or brown waxy secretions produced by vestigial apocrine sweat glands in the external ear canal.Stapes: One of the three ossicles of the middle ear. It transmits sound vibrations from the INCUS to the internal ear (Ear, Internal see LABYRINTH).Acoustic Impedance Tests: Objective tests of middle ear function based on the difficulty (impedance) or ease (admittance) of sound flow through the middle ear. These include static impedance and dynamic impedance (i.e., tympanometry and impedance tests in conjunction with intra-aural muscle reflex elicitation). This term is used also for various components of impedance and admittance (e.g., compliance, conductance, reactance, resistance, susceptance).Semicircular Canals: Three long canals (anterior, posterior, and lateral) of the bony labyrinth. They are set at right angles to each other and are situated posterosuperior to the vestibule of the bony labyrinth (VESTIBULAR LABYRINTH). The semicircular canals have five openings into the vestibule with one shared by the anterior and the posterior canals. Within the canals are the SEMICIRCULAR DUCTS.Ear, External: The outer part of the hearing system of the body. It includes the shell-like EAR AURICLE which collects sound, and the EXTERNAL EAR CANAL, the TYMPANIC MEMBRANE, and the EXTERNAL EAR CARTILAGES.Ear, Inner: The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.Scala Vestibuli: The upper chamber of the COCHLEA that is filled with PERILYMPH. It is connected to SCALA TYMPANI via helicotrema at the apex of the cochlea.Bone Conduction: Transmission of sound waves through vibration of bones in the SKULL to the inner ear (COCHLEA). By using bone conduction stimulation and by bypassing any OUTER EAR or MIDDLE EAR abnormalities, hearing thresholds of the cochlea can be determined. Bone conduction hearing differs from normal hearing which is based on air conduction stimulation via the EAR CANAL and the TYMPANIC MEMBRANE.Ear Diseases: Pathological processes of the ear, the hearing, and the equilibrium system of the body.Spinal Canal: The cavity within the SPINAL COLUMN through which the SPINAL CORD passes.Ear Ossicles: A mobile chain of three small bones (INCUS; MALLEUS; STAPES) in the TYMPANIC CAVITY between the TYMPANIC MEMBRANE and the oval window on the wall of INNER EAR. Sound waves are converted to vibration by the tympanic membrane then transmitted via these ear ossicles to the inner ear.Otoacoustic Emissions, Spontaneous: Self-generated faint acoustic signals from the inner ear (COCHLEA) without external stimulation. These faint signals can be recorded in the EAR CANAL and are indications of active OUTER AUDITORY HAIR CELLS. Spontaneous otoacoustic emissions are found in all classes of land vertebrates.Root Canal Preparation: Preparatory activities in ROOT CANAL THERAPY by partial or complete extirpation of diseased pulp, cleaning and sterilization of the empty canal, enlarging and shaping the canal to receive the sealing material. The cavity may be prepared by mechanical, sonic, chemical, or other means. (From Dorland, 28th ed, p1700)Round Window, Ear: Fenestra of the cochlea, an opening in the basal wall between the MIDDLE EAR and the INNER EAR, leading to the cochlea. It is closed by a secondary tympanic membrane.Mite Infestations: Infestations with arthropods of the subclass ACARI, superorder Acariformes.Acoustics: The branch of physics that deals with sound and sound waves. In medicine it is often applied in procedures in speech and hearing studies. With regard to the environment, it refers to the characteristics of a room, auditorium, theatre, building, etc. that determines the audibility or fidelity of sounds in it. (From Random House Unabridged Dictionary, 2d ed)Incus: One of three ossicles of the middle ear. It conducts sound vibrations from the MALLEUS to the STAPES.Ear Protective Devices: Personal devices for protection of the ears from loud or high intensity noise, water, or cold. These include earmuffs and earplugs.Cochlea: The part of the inner ear (LABYRINTH) that is concerned with hearing. It forms the anterior part of the labyrinth, as a snail-like structure that is situated almost horizontally anterior to the VESTIBULAR LABYRINTH.Ear Neoplasms: Tumors or cancer of any part of the hearing and equilibrium system of the body (the EXTERNAL EAR, the MIDDLE EAR, and the INNER EAR).Tympanic Membrane Perforation: A temporary or persistent opening in the eardrum (TYMPANIC MEMBRANE). Clinical signs depend on the size, location, and associated pathological condition.Hearing Loss, Conductive: Hearing loss due to interference with the mechanical reception or amplification of sound to the COCHLEA. The interference is in the outer or middle ear involving the EAR CANAL; TYMPANIC MEMBRANE; or EAR OSSICLES.Perceptual Distortion: Lack of correspondence between the way a stimulus is commonly perceived and the way an individual perceives it under given conditions.Otoscopy: Examination of the EAR CANAL and eardrum with an OTOSCOPE.Hearing: The ability or act of sensing and transducing ACOUSTIC STIMULATION to the CENTRAL NERVOUS SYSTEM. It is also called audition.Root Canal Irrigants: Chemicals used mainly to disinfect root canals after pulpectomy and before obturation. The major ones are camphorated monochlorophenol, EDTA, formocresol, hydrogen peroxide, metacresylacetate, and sodium hypochlorite. Root canal irrigants include also rinsing solutions of distilled water, sodium chloride, etc.Dental Pulp Cavity: The space in a tooth bounded by the dentin and containing the dental pulp. The portion of the cavity within the crown of the tooth is the pulp chamber; the portion within the root is the pulp canal or root canal.Malleus: The largest of the auditory ossicles, and the one attached to the membrana tympani (TYMPANIC MEMBRANE). Its club-shaped head articulates with the INCUS.Temporal Bone: Either of a pair of compound bones forming the lateral (left and right) surfaces and base of the skull which contains the organs of hearing. It is a large bone formed by the fusion of parts: the squamous (the flattened anterior-superior part), the tympanic (the curved anterior-inferior part), the mastoid (the irregular posterior portion), and the petrous (the part at the base of the skull).Basilar Membrane: A basement membrane in the cochlea that supports the hair cells of the ORGAN OF CORTI, consisting keratin-like fibrils. It stretches from the SPIRAL LAMINA to the basilar crest. The movement of fluid in the cochlea, induced by sound, causes displacement of the basilar membrane and subsequent stimulation of the attached hair cells which transform the mechanical signal into neural activity.Audiology: The study of hearing and hearing impairment.Root Canal Filling Materials: Materials placed inside a root canal for the purpose of obturating or sealing it. The materials may be gutta-percha, silver cones, paste mixtures, or other substances. (Dorland, 28th ed, p631 & Boucher's Clinical Dental Terminology, 4th ed, p187)Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Otitis Media with Effusion: Inflammation of the middle ear with a clear pale yellow-colored transudate.Benzethonium: Bactericidal cationic quaternary ammonium surfactant used as a topical anti-infective agent. It is an ingredient in medicaments, deodorants, mouthwashes, etc., and is used to disinfect apparatus, etc., in the food processing and pharmaceutical industries, in surgery, and also as a preservative. The compound is toxic orally as a result of neuromuscular blockade.Sound Spectrography: The graphic registration of the frequency and intensity of sounds, such as speech, infant crying, and animal vocalizations.Auditory Threshold: The audibility limit of discriminating sound intensity and pitch.Malassezia: A mitosporic fungal genus that causes a variety of skin disorders. Malassezia furfur (Pityrosporum orbiculare) causes TINEA VERSICOLOR.Acoustic Stimulation: Use of sound to elicit a response in the nervous system.Cochlear Microphonic Potentials: The electric response of the cochlear hair cells to acoustic stimulation.Audiometry: The testing of the acuity of the sense of hearing to determine the thresholds of the lowest intensity levels at which an individual can hear a set of tones. The frequencies between 125 and 8000 Hz are used to test air conduction thresholds and the frequencies between 250 and 4000 Hz are used to test bone conduction thresholds.Gerbillinae: A subfamily of the Muridae consisting of several genera including Gerbillus, Rhombomys, Tatera, Meriones, and Psammomys.Psoroptidae: Family of parasitic MITES, in the superfamily Sarcoptoidea, order Astigmata. Genera include Psoroptes and Chorioptes.Audiometry, Pure-Tone: Measurement of hearing based on the use of pure tones of various frequencies and intensities as auditory stimuli.Disarticulation: Amputation or separation at a joint. (Dorland, 28th ed)Hearing Aids: Wearable sound-amplifying devices that are intended to compensate for impaired hearing. These generic devices include air-conduction hearing aids and bone-conduction hearing aids. (UMDNS, 1999)Anal Canal: The terminal segment of the LARGE INTESTINE, beginning from the ampulla of the RECTUM and ending at the anus.Mites: Any arthropod of the subclass ACARI except the TICKS. They are minute animals related to the spiders, usually having transparent or semitransparent bodies. They may be parasitic on humans and domestic animals, producing various irritations of the skin (MITE INFESTATIONS). Many mite species are important to human and veterinary medicine as both parasite and vector. Mites also infest plants.Otitis Media: Inflammation of the MIDDLE EAR including the AUDITORY OSSICLES and the EUSTACHIAN TUBE.Tooth Apex: The tip or terminal end of the root of a tooth. (Jablonski, Dictionary of Dentistry, 1992, p62)Pitch Perception: A dimension of auditory sensation varying with cycles per second of the sound stimulus.Dermatomycoses: Superficial infections of the skin or its appendages by any of various fungi.Psychoacoustics: The science pertaining to the interrelationship of psychologic phenomena and the individual's response to the physical properties of sound.Vibration: A continuing periodic change in displacement with respect to a fixed reference. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Ear Auricle: The shell-like structure projects like a little wing (pinna) from the side of the head. Ear auricles collect sound from the environment.