Sound: A type of non-ionizing radiation in which energy is transmitted through solid, liquid, or gas as compression waves. Sound (acoustic or sonic) radiation with frequencies above the audible range is classified as ultrasonic. Sound radiation below the audible range is classified as infrasonic.Sound Localization: Ability to determine the specific location of a sound source.Heart Sounds: The sounds heard over the cardiac region produced by the functioning of the heart. There are four distinct sounds: the first occurs at the beginning of SYSTOLE and is heard as a "lubb" sound; the second is produced by the closing of the AORTIC VALVE and PULMONARY VALVE and is heard as a "dupp" sound; the third is produced by vibrations of the ventricular walls when suddenly distended by the rush of blood from the HEART ATRIA; and the fourth is produced by atrial contraction and ventricular filling.Sound Spectrography: The graphic registration of the frequency and intensity of sounds, such as speech, infant crying, and animal vocalizations.Acoustic Stimulation: Use of sound to elicit a response in the nervous system.Auditory Perception: The process whereby auditory stimuli are selected, organized, and interpreted by the organism.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)Auditory Pathways: NEURAL PATHWAYS and connections within the CENTRAL NERVOUS SYSTEM, beginning at the hair cells of the ORGAN OF CORTI, continuing along the eighth cranial nerve, and terminating at the AUDITORY CORTEX.Hearing: The ability or act of sensing and transducing ACOUSTIC STIMULATION to the CENTRAL NERVOUS SYSTEM. It is also called audition.Auditory Cortex: The region of the cerebral cortex that receives the auditory radiation from the MEDIAL GENICULATE BODY.Noise: Any sound which is unwanted or interferes with HEARING other sounds.Evoked Potentials, Auditory: The electric response evoked in the CEREBRAL CORTEX by ACOUSTIC STIMULATION or stimulation of the AUDITORY PATHWAYS.Psychoacoustics: The science pertaining to the interrelationship of psychologic phenomena and the individual's response to the physical properties of sound.Respiratory Sounds: Noises, normal and abnormal, heard on auscultation over any part of the RESPIRATORY TRACT.Auditory Threshold: The audibility limit of discriminating sound intensity and pitch.Heart Auscultation: Act of listening for sounds within the heart.Auscultation: Act of listening for sounds within the body.Vocalization, Animal: Sounds used in animal communication.Animal Communication: Communication between animals involving the giving off by one individual of some chemical or physical signal, that, on being received by another, influences its behavior.Phonocardiography: Graphic registration of the heart sounds picked up as vibrations and transformed by a piezoelectric crystal microphone into a varying electrical output according to the stresses imposed by the sound waves. The electrical output is amplified by a stethograph amplifier and recorded by a device incorporated into the electrocardiograph or by a multichannel recording machine.Music: Sound that expresses emotion through rhythm, melody, and harmony.Inferior Colliculi: The posterior pair of the quadrigeminal bodies which contain centers for auditory function.Speech Perception: The process whereby an utterance is decoded into a representation in terms of linguistic units (sequences of phonetic segments which combine to form lexical and grammatical morphemes).Phonetics: The science or study of speech sounds and their production, transmission, and reception, and their analysis, classification, and transcription. (Random House Unabridged Dictionary, 2d ed)Pitch Perception: A dimension of auditory sensation varying with cycles per second of the sound stimulus.Echolocation: An auditory orientation mechanism involving the emission of high frequency sounds which are reflected back to the emitter (animal).Air Sacs: Thin-walled sacs or spaces which function as a part of the respiratory system in birds, fishes, insects, and mammals.Loudness Perception: The perceived attribute of a sound which corresponds to the physical attribute of intensity.Cochlear Nerve: The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing.Pattern Recognition, Physiological: The analysis of a critical number of sensory stimuli or facts (the pattern) by physiological processes such as vision (PATTERN RECOGNITION, VISUAL), touch, or hearing.Speech: Communication through a system of conventional vocal symbols.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.Pitch Discrimination: The ability to differentiate tones.Evoked Potentials, Auditory, Brain Stem: Electrical waves in the CEREBRAL CORTEX generated by BRAIN STEM structures in response to auditory click stimuli. These are found to be abnormal in many patients with CEREBELLOPONTINE ANGLE lesions, MULTIPLE SCLEROSIS, or other DEMYELINATING DISEASES.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.Stethoscopes: Instruments intended to detect and study sound produced by the heart, lungs, or other parts of the body. (from UMDNS, 1999)Tinnitus: A nonspecific symptom of hearing disorder characterized by the sensation of buzzing, ringing, clicking, pulsations, and other noises in the ear. Objective tinnitus refers to noises generated from within the ear or adjacent structures that can be heard by other individuals. The term subjective tinnitus is used when the sound is audible only to the affected individual. Tinnitus may occur as a manifestation of COCHLEAR DISEASES; VESTIBULOCOCHLEAR NERVE DISEASES; INTRACRANIAL HYPERTENSION; CRANIOCEREBRAL TRAUMA; and other conditions.Strigiformes: An order of BIRDS with the common name owls characterized by strongly hooked beaks, sharp talons, large heads, forward facing eyes, and facial disks. While considered nocturnal RAPTORS, some owls do hunt by day.Reaction Time: The time from the onset of a stimulus until a response is observed.Chiroptera: Order of mammals whose members are adapted for flight. It includes bats, flying foxes, and fruit bats.Cues: Signals for an action; that specific portion of a perceptual field or pattern of stimuli to which a subject has learned to respond.Ear Canal: The narrow passage way that conducts the sound collected by the EAR AURICLE to the TYMPANIC MEMBRANE.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.Hearing Loss, Noise-Induced: Hearing loss due to exposure to explosive loud noise or chronic exposure to sound level greater than 85 dB. The hearing loss is often in the frequency range 4000-6000 hertz.Speech Acoustics: The acoustic aspects of speech in terms of frequency, intensity, and time.Olivary Nucleus: A part of the MEDULLA OBLONGATA situated in the olivary body. It is involved with motor control and is a major source of sensory input to the CEREBELLUM.Vibration: A continuing periodic change in displacement with respect to a fixed reference. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Perceptual Masking: The interference of one perceptual stimulus with another causing a decrease or lessening in perceptual effectiveness.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.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.Auditory Perceptual Disorders: Acquired or developmental cognitive disorders of AUDITORY PERCEPTION characterized by a reduced ability to perceive information contained in auditory stimuli despite intact auditory pathways. Affected individuals have difficulty with speech perception, sound localization, and comprehending the meaning of inflections of speech.Noise, Occupational: Noise present in occupational, industrial, and factory situations.Heart Murmurs: Heart sounds caused by vibrations resulting from the flow of blood through the heart. Heart murmurs can be examined by HEART AUSCULTATION, and analyzed by their intensity (6 grades), duration, timing (systolic, diastolic, or continuous), location, transmission, and quality (musical, vibratory, blowing, etc).Gryllidae: The family Gryllidae consists of the common house cricket, Acheta domesticus, which is used in neurological and physiological studies. Other genera include Gryllotalpa (mole cricket); Gryllus (field cricket); and Oecanthus (tree cricket).Brain Mapping: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.Functional Laterality: Behavioral manifestations of cerebral dominance in which there is preferential use and superior functioning of either the left or the right side, as in the preferred use of the right hand or right foot.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).Articulation Disorders: Disorders of the quality of speech characterized by the substitution, omission, distortion, and addition of phonemes.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.Time Perception: The ability to estimate periods of time lapsed or duration of time.Signal Detection, Psychological: Psychophysical technique that permits the estimation of the bias of the observer as well as detectability of the signal (i.e., stimulus) in any sensory modality. (From APA, Thesaurus of Psychological Index Terms, 8th ed.)Kinetocardiography: The graphic recording of chest wall movement due to cardiac impulses.Ultrasonics: A subfield of acoustics dealing in the radio frequency range higher than acoustic SOUND waves (approximately above 20 kilohertz). Ultrasonic radiation is used therapeutically (DIATHERMY and ULTRASONIC THERAPY) to generate HEAT and to selectively destroy tissues. It is also used in diagnostics, for example, ULTRASONOGRAPHY; ECHOENCEPHALOGRAPHY; and ECHOCARDIOGRAPHY, to visually display echoes received from irradiated tissues.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Hyperacusis: An abnormally disproportionate increase in the sensation of loudness in response to auditory stimuli of normal volume. COCHLEAR DISEASES; VESTIBULOCOCHLEAR NERVE DISEASES; FACIAL NERVE DISEASES; STAPES SURGERY; and other disorders may be associated with this condition.Audiometry, Pure-Tone: Measurement of hearing based on the use of pure tones of various frequencies and intensities as auditory stimuli.Magnetoencephalography: The measurement of magnetic fields over the head generated by electric currents in the brain. As in any electrical conductor, electric fields in the brain are accompanied by orthogonal magnetic fields. The measurement of these fields provides information about the localization of brain activity which is complementary to that provided by ELECTROENCEPHALOGRAPHY. Magnetoencephalography may be used alone or together with electroencephalography, for measurement of spontaneous or evoked activity, and for research or clinical purposes.Cochlear Implants: Electronic hearing devices typically used for patients with normal outer and middle ear function, but defective inner ear function. In the COCHLEA, the hair cells (HAIR CELLS, VESTIBULAR) may be absent or damaged but there are residual nerve fibers. The device electrically stimulates the COCHLEAR NERVE to create sound sensation.Hair Cells, Auditory: Sensory cells in the organ of Corti, characterized by their apical stereocilia (hair-like projections). The inner and outer hair cells, as defined by their proximity to the core of spongy bone (the modiolus), change morphologically along the COCHLEA. Towards the cochlear apex, the length of hair cell bodies and their apical STEREOCILIA increase, allowing differential responses to various frequencies of sound.Signal Processing, Computer-Assisted: Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.Illusions: The misinterpretation of a real external, sensory experience.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Hearing Loss, Central: Hearing loss due to disease of the AUDITORY PATHWAYS (in the CENTRAL NERVOUS SYSTEM) which originate in the COCHLEAR NUCLEI of the PONS and then ascend bilaterally to the MIDBRAIN, the THALAMUS, and then the AUDITORY CORTEX in the TEMPORAL LOBE. Bilateral lesions of the auditory pathways are usually required to cause central hearing loss. Cortical deafness refers to loss of hearing due to bilateral auditory cortex lesions. Unilateral BRAIN STEM lesions involving the cochlear nuclei may result in unilateral hearing loss.Chinchilla: A genus of the family Chinchillidae which consists of three species: C. brevicaudata, C. lanigera, and C. villidera. They are used extensively in biomedical research.Voice: The sounds produced by humans by the passage of air through the LARYNX and over the VOCAL CORDS, and then modified by the resonance organs, the NASOPHARYNX, and the MOUTH.Speech Production Measurement: Measurement of parameters of the speech product such as vocal tone, loudness, pitch, voice quality, articulation, resonance, phonation, phonetic structure and prosody.Deafness: A general term for the complete loss of the ability to hear from both ears.Phonation: The process of producing vocal sounds by means of VOCAL CORDS vibrating in an expiratory blast of air.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Hearing Tests: Part of an ear examination that measures the ability of sound to reach the brain.Discrimination (Psychology): Differential response to different stimuli.Cochlear Microphonic Potentials: The electric response of the cochlear hair cells to acoustic stimulation.Perciformes: The most diversified of all fish orders and the largest vertebrate order. It includes many of the commonly known fish such as porgies, croakers, sunfishes, dolphin fish, mackerels, TUNA, etc.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.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.Dolphins: Mammals of the families Delphinidae (ocean dolphins), Iniidae, Lipotidae, Pontoporiidae, and Platanistidae (all river dolphins). Among the most well-known species are the BOTTLE-NOSED DOLPHIN and the KILLER WHALE (a dolphin). The common name dolphin is applied to small cetaceans having a beaklike snout and a slender, streamlined body, whereas PORPOISES are small cetaceans with a blunt snout and rather stocky body. (From Walker's Mammals of the World, 5th ed, pp978-9)Amplifiers, Electronic: Electronic devices that increase the magnitude of a signal's power level or current.Speech Articulation Tests: Tests of accuracy in pronouncing speech sounds, e.g., Iowa Pressure Articulation Test, Deep Test of Articulation, Templin-Darley Tests of Articulation, Goldman-Fristoe Test of Articulation, Screening Speech Articulation Test, Arizona Articulation Proficiency Scale.Noise, Transportation: Noise associated with transportation, particularly aircraft and automobiles.Models, Neurological: Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.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)Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Hair Cells, Auditory, Inner: Auditory sensory cells of organ of Corti, usually placed in one row medially to the core of spongy bone (the modiolus). Inner hair cells are in fewer numbers than the OUTER AUDITORY HAIR CELLS, and their STEREOCILIA are approximately twice as thick as those of the outer hair cells.Orthoptera: An order of insects comprising two suborders: Caelifera and Ensifera. They consist of GRASSHOPPERS, locusts, and crickets (GRYLLIDAE).Hearing Loss: A general term for the complete or partial loss of the ability to hear from one or both ears.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Gerbillinae: A subfamily of the Muridae consisting of several genera including Gerbillus, Rhombomys, Tatera, Meriones, and Psammomys.Electroencephalography: Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain.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.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.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.Language: A verbal or nonverbal means of communicating ideas or feelings.Transducers: Any device or element which converts an input signal into an output signal of a different form. Examples include the microphone, phonographic pickup, loudspeaker, barometer, photoelectric cell, automobile horn, doorbell, and underwater sound transducer. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th 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)

Coding of sound envelopes by inhibitory rebound in neurons of the superior olivary complex in the unanesthetized rabbit. (1/910)

Most natural sounds (e.g., speech) are complex and have amplitude envelopes that fluctuate rapidly. A number of studies have examined the neural coding of envelopes, but little attention has been paid to the superior olivary complex (SOC), a constellation of nuclei that receive information from the cochlear nucleus. We studied two classes of predominantly monaural neurons: those that displayed a sustained response to tone bursts and those that gave only a response to the tone offset. Our results demonstrate that the off neurons in the SOC can encode the pattern of amplitude-modulated sounds with high synchrony that is superior to sustained neurons. The upper cutoff frequency and highest modulation frequency at which significant synchrony was present were, on average, slightly higher for off neurons compared with sustained neurons. Finally, most sustained and off neurons encoded the level of pure tones over a wider range of intensities than those reported for auditory nerve fibers and cochlear nucleus neurons. A traditional view of inhibition is that it attenuates or terminates neural activity. Although this holds true for off neurons, the robust discharge when inhibition is released adds a new dimension. For simple sounds (i.e., pure tones), the off response can code a wide range of sound levels. For complex sounds, the off response becomes entrained to each modulation, resulting in a precise temporal coding of the envelope.  (+info)

Communication signals and sound production mechanisms of mormyrid electric fish. (2/910)

The African weakly electric fishes Pollimyrus isidori and Pollimyrus adspersus (Mormyridae) produce elaborate acoustic displays during social communication in addition to their electric organ discharges (EODs). In this paper, we provide new data on the EODs of these sound-producing mormyrids and on the mechanisms they use to generate species-typical sounds. Although it is known that the EODs are usually species-specific and sexually dimorphic, the EODs of closely related sound-producing mormyrids have not previously been compared. The data presented demonstrate that there is a clear sexual dimorphism in the EOD waveform of P. isidori. Females have a multi-phasic EOD that is more complex than the male's biphasic EOD. In this respect, P. isidori is similar to its more thoroughly studied congener P. adspersus, which has a sexually dimorphic EOD. The new data also reveal that the EODs of these two species are distinct, thus showing for the first time that species-specificity in EODs is characteristic of these fishes, which also generate species-specific courtship sounds. The sound-generating mechanism is based on a drumming muscle coupled to the swimbladder. Transverse sections through decalcified male and female P. adspersus revealed a muscle that envelops the caudal pole of the swimbladder and that is composed of dorso-ventrally oriented fibers. The muscle is five times larger in males (14.5+/-4.4 microl, mean +/- s.d.) than in females (3.2+/-1.8 microl). The fibers are also of significantly larger diameter in males than in females. Males generate courtship sounds and females do not. The function of the swimbladder muscle was tested using behavioral experiments. Male P. adspersus normally produce acoustic courtship displays when presented with female-like electrical stimuli. However, local anesthesia of the swimbladder muscle muted males. In control trials, males continued to produce sounds after injection of either lidocaine in the trunk muscles or saline in the swimbladder muscles.  (+info)

Sensitivity to simulated directional sound motion in the rat primary auditory cortex. (3/910)

Sensitivity to simulated directional sound motion in the rat primary auditory cortex. This paper examines neuron responses in rat primary auditory cortex (AI) during sound stimulation of the two ears designed to simulate sound motion in the horizontal plane. The simulated sound motion was synthesized from mathematical equations that generated dynamic changes in interaural phase, intensity, and Doppler shifts at the two ears. The simulated sounds were based on moving sources in the right frontal horizontal quadrant. Stimuli consisted of three circumferential segments between 0 and 30 degrees, 30 and 60 degrees, and 60 and 90 degrees and four radial segments at 0, 30, 60, and 90 degrees. The constant velocity portion of each segment was 0.84 m long. The circumferential segments and center of the radial segments were calculated to simulate a distance of 2 m from the head. Each segment had two trajectories that simulated motion in both directions, and each trajectory was presented at two velocities. Young adult rats were anesthetized, the left primary auditory cortex was exposed, and microelectrode recordings were obtained from sound responsive cells in AI. All testing took place at a tonal frequency that most closely approximated the best frequency of the unit at a level 20 dB above the tuning curve threshold. The results were presented on polar plots that emphasized the two directions of simulated motion for each segment rather than the location of sound in space. The trajectory exhibiting a "maximum motion response" could be identified from these plots. "Neuron discharge profiles" within these trajectories were used to demonstrate neuron activity for the two motion directions. Cells were identified that clearly responded to simulated uni- or multidirectional sound motion (39%), that were sensitive to sound location only (19%), or that were sound driven but insensitive to our location or sound motion stimuli (42%). The results demonstrated the capacity of neurons in rat auditory cortex to selectively process dynamic stimulus conditions representing simulated motion on the horizontal plane. Our data further show that some cells were responsive to location along the horizontal plane but not sensitive to motion. Cells sensitive to motion, however, also responded best to the moving sound at a particular location within the trajectory. It would seem that the mechanisms underlying sensitivity to sound location as well as direction of motion converge on the same cell.  (+info)

Single-unit responses in the inferior colliculus of decerebrate cats. I. Classification based on frequency response maps. (4/910)

This study proposes a classification system for neurons in the central nucleus of the inferior colliculus (ICC) that is based on excitation and inhibition patterns of single-unit responses in decerebrate cats. The decerebrate preparation allowed extensive characterization of physiological response types without the confounding effects of anesthesia. The tone-driven discharge rates of individual units were measured across a range of frequencies and levels to map excitatory and inhibitory response areas for contralateral monaural stimulation. The resulting frequency response maps can be grouped into the following three populations: type V maps exhibit a wide V-shaped excitatory area and no inhibition; type I maps show a more restricted I-shaped region of excitation that is flanked by inhibition at lower and higher frequencies; and type O maps display an O-shaped island of excitation at low stimulus levels that is bounded by inhibition at higher levels. Units that produce a type V map typically have a low best frequency (BF: the most sensitive frequency), a low rate of spontaneous activity, and monotonic rate-level functions for both BF tones and broadband noise. Type I and type O units have BFs that span the cat's range of audible frequencies and high rates of spontaneous activity. Like type V units, type I units are excited by BF tones and noise at all levels, but their rate-level functions may become nonmonotonic at high levels. Type O units are inhibited by BF tones and noise at high levels. The existence of distinct response types is consistent with a conceptual model in which the unit types receive dominant inputs from different sources and shows that these functionally segregated pathways are specialized to play complementary roles in the processing of auditory information.  (+info)

Conductive hearing loss produces a reversible binaural hearing impairment. (5/910)

Conductive hearing loss, produced by otitis media with effusion, is widespread in young children. However, little is known about its short- or long-term effects on hearing or the brain. To study the consequences of a conductive loss for the perception and processing of sounds, we plugged the left ear canal of ferrets for 7-15 months during either infancy or adulthood. Before or during plugging, the ferrets were trained to perform a binaural task requiring the detection of a 500 Hz tone, positioned 90 degrees to the right, that was masked by two sources of broad-band noise. In one condition ("control"), both noise sources were 90 degrees right and, in the second condition ("bilateral"), one noise source was moved to 90 degrees left. Normal ferrets showed binaural unmasking: tone detection thresholds were lower (mean 10.1 dB) for the bilateral condition than for the control condition. Both groups of ear-plugged ferrets had reduced unmasking; the mean residual unmasking was 2.3 dB for the infant and 0.7 dB for the adult ear-plugged animals. After unplugging, unmasking increased in both groups (infant, 7.1 dB; adult, 6.9 dB) but not to normal levels. Repeated testing during the 22 months after unplugging revealed a gradual return to normal levels of unmasking. These results show that a unilateral conductive hearing loss, in either infancy or adulthood, impairs binaural hearing both during and after the hearing loss. They show scant evidence for adaptation to the plug and demonstrate a recovery from the impairment that occurs over a period of several months after restoration of normal peripheral function.  (+info)

Mosquito hearing: sound-induced antennal vibrations in male and female Aedes aegypti. (6/910)

Male mosquitoes are attracted by the flight sounds of conspecific females. In males only, the antennal flagellum bears a large number of long hairs and is therefore said to be plumose. As early as 1855, it was proposed that this remarkable antennal anatomy served as a sound-receiving structure. In the present study, the sound-induced vibrations of the antennal flagellum in male and female Aedes aegypti were compared, and the functional significance of the flagellar hairs for audition was examined. In both males and females, the antennae are resonantly tuned mechanical systems that move as simple forced damped harmonic oscillators when acoustically stimulated. The best frequency of the female antenna is around 230 Hz; that of the male is around 380 Hz, which corresponds approximately to the fundamental frequency of female flight sounds. The antennal hairs of males are resonantly tuned to frequencies between approximately 2600 and 3100 Hz and are therefore stiffly coupled to, and move together with, the flagellar shaft when stimulated at biologically relevant frequencies around 380 Hz. Because of this stiff coupling, forces acting on the hairs can be transmitted to the shaft and thus to the auditory sensory organ at the base of the flagellum, a process that is proposed to improve acoustic sensitivity. Indeed, the mechanical sensitivity of the male antenna not only exceeds the sensitivity of the female antenna but also those of all other arthropod movement receivers studied so far.  (+info)

Bilateral ablation of auditory cortex in Mongolian gerbil affects discrimination of frequency modulated tones but not of pure tones. (7/910)

This study examines the role of auditory cortex in the Mongolian gerbil in differential conditioning to pure tones and to linearly frequency-modulated (FM) tones by analyzing the effects of bilateral auditory cortex ablation. Learning behavior and performance were studied in a GO/NO-GO task aiming at avoidance of a mild foot shock by crossing a hurdle in a two-way shuttle box. Hurdle crossing as the conditioned response to the reinforced stimulus (CR+), as false alarm in response to the unreinforced stimulus (CR-), intertrial activity, and reaction times were monitored. The analysis revealed no effects of lesion on pure tone discrimination but impairment of FM tone discrimination. In the latter case lesion effects were dependent on timing of lesion relative to FM tone discrimination training. Lesions before training in naive animals led to a reduced CR+ rate and had no effect on CR- rate. Lesions in pretrained animals led to an increased CR- rate without effects on the CR+ rate. The results suggest that auditory cortex plays a more critical role in discrimination of FM tones than in discrimination of pure tones. The different lesion effects on FM tone discrimination before and after training are compatible with both the hypothesis of a purely sensory deficit in FM tone processing and the hypothesis of a differential involvement of auditory cortex in acquisition and retention, respectively.  (+info)

Contractile properties of muscles used in sound production and locomotion in two species of gray tree frog. (8/910)

The sound-producing muscles of frogs and toads are interesting because they have been selected to produce high-power outputs at high frequencies. The two North American species of gray tree frog, Hyla chrysoscelis and Hyla versicolor, are a diploid-tetraploid species pair. They are morphologically identical, but differ in the structure of their advertisement calls. H. chrysoscelis produces very loud pulsed calls by contracting its calling muscles at approximately 40 Hz at 20 degrees C, whereas, H. versicolor operates the homologous muscles at approximately 20 Hz at this temperature. This study examined the matching of the intrinsic contractile properties of the calling muscles to their frequency of use. I measured the isotonic and isometric contractile properties of two calling muscles, the laryngeal dilator, which presumably has a role in modulating call structure, and the external oblique, which is one of the muscles that provides the mechanical power for calling. I also examined the properties of the sartorius as a representative locomotor muscle. The calling muscles differ greatly in twitch kinetics between the two species. The calling muscles of H. chrysoscelis reach peak tension in a twitch after approximately 15 ms, compared with 25 ms for the same muscles in H. versicolor. The muscles also differ significantly in isotonic properties in the direction predicted from their calling frequencies. However, the maximum shortening velocities of the calling muscles of H. versicolor are only slightly lower than those of the comparable muscles of H. chrysoscelis. The calling muscles have similar maximum shortening velocities to the sartorius, but have much flatter force-velocity curves, which may be an adaptation to their role in cyclical power output. I conclude that twitch properties have been modified more by selection than have intrinsic shortening velocities. This difference corresponds to the differing roles of shortening velocity and twitch kinetics in determining power output at differing frequencies.  (+info)

  • From a dog's bark to a referee's whistle, from a baby's cry to a rock concert, the sound we hear is caused by vibrations that create fluctuations in the atmosphere much like a tuning fork will produce. (
  • He elevated sound to a science by studying vibrations and the correlation between frequency and the source of sound. (
  • In the Discorsi Galileo thought out the vibrating complexion of sounds, and asserted that the pitch was correlated with the number of vibrations. (
  • Sound Surgical markets leading surgical and non-invasive body shaping products utilizing ultrasound technology. (
  • Why Do People Like Loud Sound? (
  • Many people choose to expose themselves to potentially dangerous sounds such as loud music, either via speakers, personal audio systems, or at clubs. (
  • To compare the model to data, we interviewed a group of people who were either regular nightclub-goers or who controlled the sound levels in nightclubs (bar managers, musicians, DJs, and sound engineers) about loud sound. (
  • Results showed four main themes relating to the enjoyment of loud sound: arousal/excitement, facilitation of socialisation, masking of both external sound and unwanted thoughts, and an emphasis and enhancement of personal identity. (
  • Consideration of the data generated by the analysis revealed a complex of influential factors that support people in wanting exposure to loud sound. (
  • Loud sound causes damage to the auditory system, and is regarded as annoying with serious impacts on physical and mental health [ 1 ]. (
  • Every sound we hear is the result of a sound source that has induced a vibration. (
  • As a sound vibration is produced, the fluctuations are passed through any of these mediums transferring energy from one particle of the medium to its neighboring particles, much like doing a "wave" at a sporting event. (
  • As the sound source produces its vibration, the energy transfer begins to reflect off all six surfaces in a room faster than we can blink, and begin returning back into the room. (
  • Medial theories - exemplified by mainstream acoustics - locate sounds in the medium between the resonating object and the hearer. (
  • Acoustics (from the Greek word akoustos which means "heard") is the science of how sound is produced, transmitted, controlled, and the effects of sound. (
  • The navigation rules for meeting head-on, crossing, and overtaking situations are examples of when sound signals are required. (
  • Your project can be anything involving sound or using a transducer for converting one form of energy into another. (
  • Let's start with a basic understanding of the sound wave. (
  • A tightly racked set of billiards balls will mirror sound wave activity when the cue ball strikes the front ball in the rack. (
  • Sound wave behavior actually radiates outward from its source like a pebble wave in a pond, traveling along at an average speed of 770 mph. (
  • As we teach in our course here at the Academy, a Hertz is equal to one sound wave cycle per second as is illustrated at the top of this page. (
  • In our course on the Decibel, we learn that as a sound wave travels over distance and time, the intensity of the wave will decrease. (
  • Your project can involve electroacoustic transducers that convert a sound wave to some form of electric signal such as loudspeakers, microphones, particle velocity sensors, hydrophones and sonar projectors. (
  • Electret microphones and condenser microphones employ electrostatics-as the sound wave strikes the microphone's diaphragm, it moves and induces a voltage change. (
  • This subjective or perceived magnitude of a sound by an individual is called its loudness. (
  • The loudness of a sound is not equal with its sound pressure level and differs for different frequencies. (
  • In order to assess loudness of a sound the isophonic curves are explored. (
  • While sound pressure measurements should give a reading of the sound pressure in dB SPL , in the context of human hearing it is more practical to provide also a value which corresponds more closely to the hearing sensation or loudness in phones. (
  • The A, B, and C filters used currently in sound-level meters were aimed at mimicking isoloudness curves over frequency under different conditions of sound intensities, i.e. for sounds of low, medium, and high loudness levels, respectively (IEC 651, 1979). (
  • In current practice, the A- weighting curve filter is used to weight sound pressure levels as a function of frequency, approximately in accordance with the frequency response characteristics of the human auditory system for pure tones. (
  • Sound Surgical's non-invasive [email protected] Shape system targets cellulite by heating fatty tissue in conjunction with lymphatic massage. (
  • Sound healing therapy helps to restore Harmony and Balance to the body's biological rhythms and processes, re-establishing correct functioning of the Endocrine system (the glands) and thus releasing powerful healing hormones such as endorphins and serotonins into the body. (
  • You do NOT need to be sick to experience the deep healing and relaxing power of a Sound Therapy Treatment. (
  • Sound Healing instruments are used, some of which are applied to the physical body, others played around the body in the subtle energy fields and energy centres (chakras). (
  • Tuning Forks, Singing Bowls (both Tibetan and Quartz Crystal singing bowls), and the amazing Monochord Sound Treatment Bed are just some of the Sound Healing tools used in a Sound Therapy Session. (
  • Since the sounds that act as "triggers" in this condition are quite common at home, work place and in social gatherings, misophonia has devastating effects on social, family and personal life of the sufferer. (
  • Start your sound effects search by typing in a keyword in the panel above - or browsing through a sound effects category below. (
  • When you find what you're looking for, purchase and download sound effects immediately - fully licensed for use in your productions. (
  • All sound effects downloads are available in both WAV and MP3 formats here at (
  • Your single sound effects purchase entitles you to download both files - as many times as you want. (
  • Selected Sound Effects CDs are also Available to Purchase for Download as zip files - scroll down this page to see some of the available selections. (
  • Vessels less than 39.4 feet (12 meters) in length, which includes PWC, must have some way of making an efficient sound signal. (
  • Vessels that are 39.4 feet (12 meters) or more in length must have a sound-producing device that can produce an efficient sound signal. (
  • If you pluck a string, it vibrates back and forth, transmitting sound energy into the hollow wooden body of the guitar, making it resonate and amplifying the sound. (
  • while the sound originates at a distance and we can hear that it is coming from a direction and even place, and while there is no auditory experience of hearing that the sound is where we are, the sound that we hear is nonetheless where we are (p. 447). (