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eMedicine - Impedance Audiometry : Article by Kathleen CM Campbell, PhD   (Site not responding. Last check: 2007-09-17) Acoustic reflex thresholds generally are determined in response to stimuli of 500, 1000, 2000, and 4000 Hz. For the contralateral or crossed acoustic reflex, present the stimulus to the ear opposite the ear that is monitored for response. However, no acoustic reflex is present when the left ear is stimulated and the recording is taken from the left ear, and no acoustic reflex is present when the right ear is stimulated and the recording is taken from the left ear. www.emedicine.com /ent/topic374.htm   (3095 words)

Acoustic reflex The acoustic reflex is an involuntary muscle contraction that occurs in the middle ear of mammals in response to high-intensity sound stimuli. The reflex decreases the transmission of vibrational energy to the cochlea, where it is converted into electrical impulses to be processed by the brain. The acoustic reflex normally only occurs at relatively high intensities; activation for quieter sounds can indicate ear dysfunction and absence of acoustic reflex can indicate neural hearing loss. www.mrsci.com /Neurology/Acoustic_reflex.php   (122 words)

Acoustic Reflexes   (Site not responding. Last check: 2007-09-17) Acoustic reflexes measure the stapedius and tensor tympani reflex generated eardrum movement in response to intense sound. A typical setup to measure the stapedius reflex is a tympanometer having a method of delivering both a sound to either ear as well as measuring the admittance of the tympanic membrane. The simplest stapedius reflex arc involving the fewest possible neurons would involve spiral ganglion neurons, the auditory nerve, the cochlear nucleus, the superior olive, the facial nerve nucleus, the facial nerve, and the stapedius muscle. www.tchain.com /otoneurology/testing/acoustic_reflexes.htm   (478 words)

ROOM ACOUSTIC SOFTWARE REFLEX   (Site not responding. Last check: 2007-09-17) This last feature allows the acoustical designer to address the spatialization of a room, an aspect of room acoustics which is often left aside because of the lack of proper tools to adress it. REFLEX is a LISP program designed to be used with AUTOCAD: it is a powerful design tool which actually allows the acoustical designer to modify the design of the room. Orient acoustical reflectors to optimize the acoustic spatialization of a room by redirecting first reflexions with the proper delay and angle of incidence where they are most needed. www.mjm.qc.ca /en/reflex.html   (217 words)

Assessment of Peripheral and Central Auditory Function   The afferent portion of the reflex is the ipsilateral eighth nerve to cochlear nuclei. The acoustic reflex in ears with cochlear disorders is determined primarily by the degree of the sensorineural hearing loss. The efferent limb of the reflex is explored in the diagnosis of ossicular chain disorders, such as otosclerosis and discontinuity, and facial nerve pathology. www.utmb.edu /otoref/Grnds/Auditory-function-2004-0211/Auditory-function-2004-0211.htm   (4713 words)

ACOUSTIC NEUROMA Acoustic neuromas are a rare cause of unilateral hearing loss as well as other symptoms related to the ear and brain. Acoustic neuromas, also known as vestibular schwannomas, are non-malignant tumors of the 8th cranial nerve. Acoustic neuroma caused by type-II neurofibromatosis should be suspected in young patients and those with a family history of neural tumors. www.tchain.com /otoneurology/disorders/tumors/acoustic_neuroma.htm   (2899 words)

Fear conditioned potentiation of the acoustic blink reflex in patients with cerebellar lesions -- Maschke et al. 68 ... In the habituation phase, short term habituation of the acoustic blink reflex was preserved in all cerebellar patients. The peak amplitude of the acoustic blink reflex Long-term habituation of the acoustic startle response: role of the cerebellar vermis. jnnp.bmjjournals.com /cgi/content/full/68/3/358   (4024 words)

1999; Suppression of the click-rate induced facilitation of acoustic reflex thresholds due to contralateral stimuli Ipsilateral acoustic reflex thresholds are known to improve with an increase in the click-repetition rate (Rawool, Scand Audiol 1995; 24:199-205; J Gerontol Biol Sci 1996; 51A:B124-131). Contralateral acoustic stimuli are known to cause suppression of otoacoustic emissions and auditory nerve response due to the activation of the efferent pathways. Acoustic reflex thresholds were established for each subject by placing the probe in the left ear and presenting the clicks to the right ear, in two conditions. www.aro.org /archives/1999/814.html   (348 words)

eMedicine - Impedance Audiometry : Article Excerpt by: Kathleen CM Campbell, PhD   (Site not responding. Last check: 2007-09-17) The primary purpose of impedance audiometry is to determine the status of the tympanic membrane and middle ear via tympanometry. The secondary purpose of this test is to evaluate acoustic reflex pathways, which include cranial nerves (CN) VII and VIII and the auditory brainstem. Acoustic immittance is a measurement of energy or air pressure flow, which involves the ear canal, eardrum, ossicular chain, tensor tympani, stapedius muscle, cochlea, CNs VII and VIII, and the brainstem. www.emedicine.com /ent/byname/impedance-audiometry.htm   (240 words)

Position Paper: Aural Acoustic Immittance Measurements April 1991 The aural acoustic immittance test battery (tympanometry and acoustic reflex measurements) reflects the physical and physiological status of the eardrum, middle ear, cochlea, seventh and eighth cranial nerves and the auditory pathway in the brainstem. The use of acoustic reflexes to predict hearing levels is not an accepted part of clinical audiologic practice today and is not substantiated by the professional literature. The aural acoustic immittance test battery has one purpose: to assess auditory function by indicating the physical and physiological status of the eardrum, middle ear, cochlea, seventh and eighth cranial nerves and the auditory pathway in the brainstem. www.csha.org /position_papers/aural_acoustic.htm   (509 words)

ISVR Consulting - Vocabulary of Audiology The reflex is commonly described as ipsilateral or contralateral, depending on which side the response is observed relative to the stimulus. The reflex is recognized by a change in aural immittance as an increasing stimulus level reaches and surpasses the acoustic reflex threshold. For a given ear, the sound pressure level delivered by an earphone in a specified ear simulator or acoustic coupler when the earphone is activated by the same electrical signal as that which elicits the monaural threshold of hearing in the given ear using the same earphone. www.isvr.co.uk /reprints/vocab.htm   (13128 words)

Reflex Excitability Regulates Prepulse Inhibition -- Schicatano et al. 20 (11): 4240 -- Journal of Neuroscience short-lasting excitation and long-lasting inhibition of the reflex 6-OHDA lesions increase the excitability of trigeminal reflex blinks. Koch M, Kungel M, Herbert H (1993) Cholinergic neurons in the pedunculopontine tegmental nucleus are involved in the mediation of prepulse inhibition of the acoustic startle response in the rat. www.jneurosci.org /cgi/content/full/20/11/4240   (4837 words)

Acoustic Immittance Measures for Hearing Acoustic immittance measures are a battery of tests including tympanometry, acoustic reflex test, and static acoustic impedance. Acoustic reflex test measures the ability of a tiny muscle in the middle ear to contract when a loud sound occurs. The absence of the acoustic reflex may indicate, among other things, lesions of the middle ear, acoustic tumors, otosclerosis, facial nerve involvement of the probe ear side, and surgical removal or congenital absence of the stapes. www.bcbst.com /MPManual/Acoustic_Immittance_Measures_for_Hearing.htm   (538 words)

Acoustic reflex frequency selectivity in single stapedius motoneurons of the cat -- Kobler et al. 68 (3): 807 -- ... Acoustic reflex frequency selectivity in single stapedius motoneurons of the cat -- Kobler et al. that the stapedius acoustic reflex is triggered by summed activity of acoustic reflex is to reduce the masking of responses to high-frequency jn.physiology.org /cgi/content/abstract/68/3/807   (310 words)

Assessment of Peripheral and Central Auditory Function(Mar.2000) An acoustic wave strikes the eardrum of the normal ear and a portion of the signal is transmitted through the middle ear to the cochlea while the remaining part of the wave is reflected back out the external canal. Several studies have shown that the threshold of the contralateral acoustic stapedius reflex (ASR) is 80 to 85 dB HL for frequencies ranging from 500 to 4000 Hz. Acoustic reflex decay measures the ability of the stapedius muscle to maintain sustained contraction. www.utmb.edu /otoref/Grnds/Auditory-assessment-200003/Auditory_Assess_200003.htm   (4576 words)

Washington Audiology and Imaging Center: Library: Definitions and Glossary Acoustic Reflex Threshold is a middle ear measurement of stapedius muscle response to higher intensity and adequate duration sounds for individual frequencies. Acoustic reflex decay test assesses the integrity of CN VIII. A contralateral continuous tone is presented for 10 seconds at a stimulus level 10 dB above the acoustic reflex threshold for that stimulus frequency in that ear. www.waicenter.com /Library/glossary.htm   (1803 words)

Acoustical Society of America 138th Meeting Lay Language Papers Hence, changes in the startle reflex are now widely used to study how the brain generates fear, anxiety, or gates irrelevant sensory information. In 1982 our laboratory proposed that acoustic startle in the rat was mediated by four synapses: three in the brainstem (the ventral cochlear nucleus, an area to the middle and just below the ventral nucleus of the lateral lemniscus, and the nucleus reticularis pontis caudalis) and one synapse onto motoneurons in the spinal cord. Electrolytic lesions of these nuclei eliminated acoustic startle while single pulse electrical stimulation of these nuclei elicited startle-like responses with a progressively shorter latency (less lag time between stimulus and response) as the electrode was moved farther down the startle pathway. www.acoustics.org /press/138th/davis.htm   (767 words)

ACOUSTIC NEUROMA Acoustic neuromas are a rare cause of unilateral hearing loss, dizziness, as well as rarely other symptoms related to the brain. In spite of the usual origin of acoustics in the inferior vestibular nerve (Komatsuzaki and Tsunoda, 2001), vertigo (spinning) is not common, occurring in only about 20 percent of persons with acoustic neuroma. A "moderate" acoustic is 1.5-3 cm, and a "Large" acoustic is 3 cm or greater. www.dizziness-and-balance.com /disorders/tumors/acoustic_neuroma.htm   (4943 words)

Acoustic startle in maltreated children Journal of Abnormal Child Psychology - Find Articles The present study is an initial exploration of the effects of maltreatment on the strength of the acoustic reflex in children. The acoustic startle reflex is an obligatory response to a sudden and unexpected stimulus that is marked by the cessation of ongoing behaviors and by a particular series of protective behaviors (Davis, 1984; Landis & Hunt, 1939). The simple reflex pathway for acoustic startle proceeds from the ear to the ventral cochlear nucleus to the caudal pontine reticular nucleus and, from there, to the spinal cord and to muscles, including orbicularis oculi. www.findarticles.com /p/articles/mi_m0902/is_4_31/ai_104634481   (750 words)

Product Manuals An acoustic reflex is elicited by presenting a very loud stimulus to the auditory pathway. During acoustic reflex testing, the stimulus is presented to the ear canal either through a probe or an earphone (insert phone). Acoustic Reflex, expressed as a yes/no, dB HL or dB HL and a curve, signifies the level at which the acoustic reflex causes the stapedial muscle to contract. www.viasyshealthcare.com /prod_serv/prodmanuals.aspx?config=ps_prod_manual_tympano2   (2570 words)

Green Cross Foundation In distinction to the orienting response, which consists of a turning in the direction of a novel sound, the acoustic startle reflex is a survival mechanism of alarm that rapidly alerts and arouses an animal perceiving a loud noise. The acoustic startle mechanism in humans can be routinely measured through muscle movement, and changes in heart rate, and skin conductance. Shalev has shown that patients who developed PTSD from various types of trauma fail to inhibit their acoustic startle reflex, which may be related to the exaggerated startle response. www.greencross.org /_Research/Vol1-2.asp   (630 words)

THE MERCK MANUAL OF GERIATRICS, Ch. 129, Ear Disorders Acoustic neuroma is a benign tumor derived from Schwann cells that sheathe the vestibular nerve. Most acoustic neuromas that occur sporadically (ie, that are not part of neurofibromatosis type 2, a hereditary disorder) are diagnosed in people age 30 to 60. The acoustic reflex may be abnormal or absent. www.merck.com /mrkshared/mmg/sec15/ch129/ch129j.jsp   (785 words)

California Ear Institute - (650) 494-1000 - Adult Acoustic Immittance Measures Absence or presence of acoustic reflexes for various presentations may be important in the differential diagnosis of both peripheral and central disorders of the auditory system such as vestibular schwannoma link or facial nerve disorders link. Reflex decay is defined as a decline in the contraction of the muscle during a sustained stimulating signal. In patients with normal middle ear and reflex thresholds, there is no decay during the presentation of the tone. www.californiaearinstitute.com /audiology/acoustic_immittance.php   (578 words)

Michael's Audiology Page Acoustic reflex tests are valuable assessment tools used to help determine whether hearing loss is due to middle ear, cochlear, or retrocochlear pathology. Acoustic reflex test procedures for those individuals who may have retrocochlear pathology requires presenting stimuli at very high intensities. That is because reflex decay is measured at 10 dB above the level of the reflex decay, or in this case, above 115 dB SPL. members.fortunecity.com /michaelder/immittance/art.html   (563 words)

Bulletin of otorhinolaringology - Abstracts ¹6 2001 Basic diagnostic criteria for perilymphatic fistulas of the labyrinth (PFL) comprise previous trauma or psychoemotional stress, unilateral acute affection of the acoustic and vestibular functions, severe noise in the ears, mixed hypoacusis, lower hearing thresholds in change of the head position, alteration of stabilogram parameters in rising pressure in the external acoustic meatus. In ANH of traumatic, vascular, pharmacological and infectious etiology tympanogram was normal with registration of the acoustic reflex with high amplitude. In allergic ANH, motility of the tympanic membrane is abnormal, in spite of the absence of serous liquid in the tympanic cavity and patency of the auditory tube, the acoustic reflex is not registered. mediasphera.aha.ru /otorino/2001/6/e6-01ref.htm   (1279 words)

Muscarinic Cholinergic Modulation of Prepulse Inhibition of the Acoustic Startle Reflex -- Jones and Shannon 294 (3): ... Braff DL, Grillion C and Geyer MA (1992) Gating and habituation of the startle reflex in schizophrenic patients. Koch M, Kungel M and Herbert H (1993) Cholinergic neurons in the pedunculopontine tegmental nucleus are involved in the mediation of prepulse inhibition of the acoustic startle response in the rat. Wan FJ and Swerdlow NR (1993) Intra-accumbens infusion of quinpirole impairs sensorimotor gating of acoustic startle in rats. www.jpet.org /cgi/content/full/294/3/1017   (3976 words)

The National Institutes of Health (NIH) Consensus Development Program: Acoustic Neuroma We use the term vestibular schwannomas throughout this report because these tumors are composed of Schwann cells and typically involve the vestibular rather than the acoustic division of the 8th cranial nerve. There is a consensus that intraoperative real-time neurologic monitoring improves the surgical management of vestibular schwannoma, including the preservation of facial nerve function and possibly improved hearing preservation by the use of intraoperative auditory brainstem response monitoring. There are a number of devices that can be used to allow for partial compensation to make the acoustic signal louder than the background noise or bring sound from the impaired ear to the hearing ear. www.consensus.nih.gov /1991/1991AcousticNeuroma087html.htm   (5387 words)

Welcome to Beltone.com - This area is for Students and Professors Reflexive tightening of the middle ear muscles in reaction to loud sounds. The reflex response when stimulus is presented to the opposite ear from where the response is measured. The reflex response when the stimulus is presented to the same ear where the response is measured. www.beltone.com /edu/aud_terms_content.asp   (1678 words)

ab_disorders_supersite|Glossary Of Terms|R - S Reflex activating stimulus (RAS): A pure tone or other acoustic signal of high intensity designed to cause the stapedial muscle to contract. The RAS can be presented through the probe assembly of an immittance meter to observe an acoustic reflex in the ear that houses the probe tip (the ipsilateral reflex), or it can be presented via an earphone in the ear opposite the probe (the contralateral acoustic reflex). Sensitivity Prediction from the Acoustic Reflex (SPAR): Prediction of approximate degree of hearing impairment based on the level of pure tones versus a broadband noise required to elicit the acoustic reflex. wps.ablongman.com /ab_disorders_supersite/0,6776,59911-,00.html   (3192 words)

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