Made by DATEXIS (Data Science and Text-based Information Systems) at Beuth University of Applied Sciences Berlin
Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
          Funded by The Federal Ministry for Economic Affairs and Energy; Grant: 01MD19013D, Smart-MD Project, Digital Technologies
          
        
Universal Newborn Hearing Screenings (UNHS) is mandated in a majority of the United States. Auditory neuropathy is sometimes difficult to catch right away, even with these precautions in place. Parental suspicion of a hearing loss is a trustworthy screening tool for hearing loss, too; if it is suspected, that is sufficient reason to seek a hearing evaluation from an audiologist.
In most parts of Australia, hearing screening via AABR testing is mandated, meaning that essentially all congenital (i.e., not those related to later onset degenerative disorders) auditory neuropathy cases should be diagnosed at birth.
A number of computer-based auditory training programs exist for children with generalized Auditory Processing Disorders (APD). In the visual system, it has been proven that adults with amblyopia can improve their visual acuity with targeted brain training programs (perceptual learning). A focused perceptual training protocol for children with amblyaudia called Auditory Rehabilitation for Interaural Asymmetry (ARIA) was developed in 2001 which has been found to improve dichotic listening performance in the non-dominant ear and enhance general listening skills. ARIA is now available in a number of clinical sites in the U.S., Canada, Australia and New Zealand. It is also undergoing clinical research trials involving electrophysiologic measures and activation patterns acquired through functional magnetic resonance imaging (fMRI) techniques to further establish its efficacy to remediate amblyaudia.
When testing the auditory system, there really is no characteristic presentation on the audiogram.
When diagnosing someone with auditory neuropathy, there is no characteristic level of functioning either. People can present relatively little dysfunction other than problems of hearing speech in noise, or can present as completely deaf and gaining no useful information from auditory signals.
Hearing aids are sometimes prescribed, with mixed success.
Some people with auditory neuropathy obtain cochlear implants, also with mixed success.
A clinical diagnosis of amblyaudia is made following dichotic listening testing as part of an auditory processing evaluation. Clinicians are advised to use newly developed dichotic listening tests that provide normative cut-off scores for the listener's dominant and non-dominant ears. These are the Randomized Dichotic Digits Test and the Dichotic Words Test. Older dichotic listening tests that provide normative information for the right and left ears can be used to supplement these two tests for support of the diagnosis (). If performance across two or more dichotic listening tests is normal in the dominant ear and significantly below normal in the non-dominant ear, a diagnosis of amblyaudia can be made. The diagnosis can also be made if performance in both ears is below normal but performance in the non-dominant ear is significantly poorer, thereby resulting in an abnormally large asymmetry between the two ears. Amblyaudia is emerging as a distinct subtype of auditory processing disorder (APD).
Auditory perception can improve with time.There seems to be a level of neuroplasticity that allows patients to recover the ability to perceive environmental and certain musical sounds. Patients presenting with cortical hearing loss and no other associated symptoms recover to a variable degree, depending on the size and type of the cerebral lesion. Patients whose symptoms include both motor deficits and aphasias often have larger lesions with an associated poorer prognosis in regard to functional status and recovery.
Cochlear or auditory brainstem implantation could also be treatment options. Electrical stimulation of the peripheral auditory system may result in improved sound perception or cortical remapping in patients with cortical deafness. However, hearing aids are an inappropriate answer for cases like these. Any auditory signal, regardless if has been amplified to normal or high intensities, is useless to a system unable to complete its processing. Ideally, patients should be directed toward resources to aid them in lip-reading, learning American Sign Language, as well as speech and occupational therapy. Patients should follow-up regularly to evaluate for any long-term recovery.
1. SCAN is the most common tool for diagnosing APD, and it also standardized. It is composed for four subsets: discrimination of monaurally presented single words against background noise, acoustically degraded single words, dichotically presented single words, sentence stimuli. Different versions of the test are used depending on the age of the patient.
2. Random Gap Detection Test (RGDT) is also a standardized test. It assesses an individual’s gap detection threshold of tones and white noise. The exam includes stimuli at four different frequencies (500, 1000, 2000, and 4000 Hz) and white noise clicks of 50 ms duration. It is a useful test because it provides an index of auditory temporal resolution. In children, an overall gap detection threshold greater than 20 ms means they have failed.
3. Gaps in Noise Test (GIN) also measures temporal resolution by testing the patient's gap detection threshold in white noise.
4. Pitch Patterns Sequence Test (PPT) and Duration Patterns Sequence Test (DPT) measure auditory pattern identification. The PPS has s series of three tones presented at either of two pitches (high or low). Meanwhile, the DPS has a series of three tones that vary in duration rather than pitch (long or short). Patients are then asked to describe the pattern of pitches presented.
Individuals with conduction aphasia are able to express themselves fairly well, with some word finding and functional comprehension difficulty. Although people with aphasia may be able to express themselves fairly well, they tend to have issues repeating phrases, especially phrases that are long and complex. When asked to repeat something, the patient will be unable to do so without significant difficulty, repeatedly attempting to self-correct ("conduite d'approche"). When asked a question, however, patients can answer spontaneously and fluently.
Several standardized test batteries exist for diagnosing and classifying aphasias. These tests are capable of identifying conduction aphasia with relative accuracy. The Boston Diagnostic Aphasia Examination (BDAE) and the Western Aphasia Battery (WAB) are two commonly used test batteries for diagnosing conduction aphasia. These examinations involve a set of tests, which include asking patients to name pictures, read printed words, count aloud, and repeat words and non-words (such as "shwazel").
Research has shown that PC based spatial hearing training software can help some of the children identified as failing to develop their spatial hearing skills (perhaps because of frequent bouts of otitis media with effusion). Further research is needed to discover if a similar approach would help those over 60 to recover the loss of their spatial hearing. One such study showed that dichotic test scores for the left ear improved with daily training. Related research into the plasticity of white-matter (see Lövdén et al. for example) suggests some recovery may be possible.
Music training leads to superior understanding of speech in noise across age groups and musical experience protects against age-related degradation in neural timing. Unlike speech (fast temporal information), music (pitch information) is primarily processed by areas of the brain in the right hemisphere. Given that it seems likely that the right ear advantage (REA) for speech is present from birth, it would follow that a left ear advantage for music is also present from birth and that MOC efferent inhibition (of the right ear) plays a similar role in creating this advantage. Does greater exposure to music increase conscious control of cochlear gain and inhibition? Further research is needed to explore the apparent ability of music to promote an enhanced capability of speech in noise recognition.
Bilateral digital hearing aids do not preserve localization cues (see, for example, Van den Bogaert et al., 2006) This means that audiologists when fitting hearing aids to patients (with a mild to moderate age related loss) risk negatively impacting their spatial hearing capability. With those patients who feel that their lack of understanding of speech in background noise is their primary hearing difficulty then hearing aids may simply make their problem even worse - their spatial hearing gain will be reduced by in the region of 10 dB. Although further research is needed, there is a growing number of studies which have shown that open-fit hearing aids are better able to preserve localisation cues (see, for example, Alworth 2011)
Cortical deafness is a rare form of sensorineural hearing loss caused by damage to the primary auditory cortex. Cortical deafness is an auditory disorder where the patient is unable to hear sounds but has no apparent damage to the anatomy of the ear (see auditory system), which can be thought of as the combination of auditory verbal agnosia and auditory agnosia. Patients with cortical deafness cannot hear any sounds, that is, they are not aware of sounds including non-speech, voices, and speech sounds. Although patients appear and feel completely deaf, they can still exhibit some reflex responses such as turning their head towards a loud sound.
Cortical deafness is caused by bilateral cortical lesions in the primary auditory cortex located in the temporal lobes of the brain. The ascending auditory pathways are damaged, causing a loss of perception of sound. Inner ear functions, however, remains intact. Cortical deafness is most often cause by stroke, but can also result from brain injury or birth defects. More specifically, a common cause is bilateral embolic stroke to the area of Heschl's gyri. Cortical deafness is extremely rare, with only twelve reported cases. Each case has a distinct context and different rates of recovery.
It is thought that cortical deafness could be a part of a spectrum of an overall cortical hearing disorder. In some cases, patients with cortical deafness have had recovery of some hearing function, resulting in partial auditory deficits such as auditory verbal agnosia. This syndrome might be difficult to distinguish from a bilateral temporal lesion such as described above.
NIHL can be prevented through the use of simple, widely available, and economical tools. This includes but is not limited to personal noise reduction through the use of ear protection (i.e. earplugs and earmuffs), education, and hearing conservation programs. For the average person, there are three basic things that can be kept in mind to reduce NIHL, “walk away, turn it down, protect your ears.”
Non-occupational noise exposure is not regulated or governed in the same manner as occupational noise exposure; therefore prevention efforts rely heavily on education awareness campaigns and public policy. The WHO cites that nearly half of those affected by hearing loss could have been prevented through primary prevention efforts such as: “reducing exposure (both occupational and recreational) to loud sounds by raising awareness about the risks; developing and enforcing relevant legislation; and encouraging individuals to use personal protective devices such as earplugs and noise-cancelling earphones and headphones.”
The basic diagnostic test is similar to a normal audiogram. The difference is that additionally to the hearing threshold at each test frequency also the lowest uncomfortable sound level is measured. This level is called "loudness discomfort level" (LDL) or "uncomfortable loudness level" (ULL). In patients with hyperacusis this level is considerably lower than in normal subjects, and usually across most parts of the auditory spectrum.
Sign language therapy has been identified as one of the top five most common treatments for auditory verbal agnosia. This type of therapy is most useful because, unlike other treatment methods, it does not rely on fixing the damaged areas of the brain. This is particularly important with AVA cases because it has been so hard to identify the causes of the agnosia in the first place, much less treat those areas directly. Sign language therapy, then, allows the person to cope and work around the disability, much in the same way it helps deaf people. In the beginning of therapy, most will work on identifying key objects and establishing an initial core vocabulary of signs. After this, the patient graduates to expand the vocabulary to intangible items or items that are not in view or present. Later, the patient learns single signs and then sentences consisting of two or more signs. In different cases, the sentences are first written down and then the patient is asked to sign them and speak them simultaneously. Because different AVA patients vary in the level of speech or comprehension they have, sign language therapy learning order and techniques are very specific to the individual's needs.
Treating auditory verbal agnosia with intravenous immunoglobulin (IVIG) is controversial because of its inconsistency as a treatment method. Although IVIG is normally used to treat immune diseases, some individuals with auditory verbal agnosia have responded positively to the use of IVIG. Additionally, patients are more likely to relapse when treated with IVIG than other pharmacological treatments. IVIG is, thus, a controversial treatment as its efficacy in treating auditory verbal agnosia is dependent upon each individual and varies from case to case.
Learning of the central nervous system by "plasticity" or biological maturation over time does not improve the performance of monaural listening. In addition to conventional methods for improving the performance of the impaired ear, there are also hearing aids adapted to unilateral hearing loss which are of very limited effectiveness due to the fact that they don't restore the stereo hearing ability.
- Contralateral Routing of Signals (CROS) hearing aids are hearing aids that take sound from the ear with poorer hearing and transmit to the ear with better hearing. There are several types of CROS hearing aid:
- conventional CROS comprises a microphone placed near the impaired ear and an amplifier (hearing aid) near the normal ear. The two units are connected either by a wire behind the neck or by wireless transmission. The aid appears as two behind-the-ear hearing aids and is sometimes incorporated into eyeglasses.
- CIC transcranial CROS comprises a bone conduction hearing aid completely in the ear canal (CIC). A high-power conventional air conduction hearing aid fits deeply into the patient’s deaf ear. Vibration of the bony walls of the ear canal and middle ear stimulates the normal ear by means of bone conduction through the skull.
- BAHA transcranial CROS Bone Anchored Hearing Aid (BAHA): a surgically implanted abutment transmits sound from the deaf ear by direct bone conduction and stimulates the cochlea of the normal hearing ear.
- SoundBite Intraoral bone conduction which uses bone conduction via the teeth. One component resembles a conventional behind-the-ear hearing aid that wirelessly connects to a second component worn in the mouth that resembles a conventional dental appliance.
In Germany and Canada, cochlear implants have been used with great success to mostly restore the stereo hearing ability, minimizing the impacts of the SSD and the quality of life of the patient.
School-age children with unilateral hearing loss tend to have poorer grades and require educational assistance. This is not the case with everyone, however. They can also be perceived to have behavioral issues.
People afflicted with UHL have great difficulty locating the source of any sound. They may be unable to locate an alarm or a ringing telephone. The swimming game Marco Polo is generally impossible for them.
When wearing stereo headphones, people with unilateral hearing loss can hear only one channel, hence the panning information (volume and time differences between channels) is lost; some instruments may be heard better than others if they are mixed predominantly to one channel, and in extreme cases of sound production, such as complete stereo separation or stereo-switching, only part of the composition can be heard; in games using 3D audio effects, sound may not be perceived appropriately due to coming to the disabled ear. This can be corrected by using settings in the software or hardware—audio player, OS, amplifier or sound source—to adjust balance to one channel (only if the setting downmixes sound from both channels to one), or there may be an option to outright downmix both channels to mono. Such settings may be available via the device or software's accessibility features. As hardware solutions, stereo-to-mono adapters may be available to receive mono sound in stereo headphones from a stereo sound source, or some monaural headsets for cellphones and VOIP communication may combine stereo sound to mono (though headphones for voice communication typically offer lower audio quality than headphones targeted for listening to music). From the standpoint of sound fidelity, sound information in downmixed mono channel will, in any case, differ from that in either of the source channels or what is perceived by a normal-hearing person, thus technically some audio quality is lost (for example, the same or slightly different sound occurrences in two channels, with time delay between them, will be merged to a sound in the mono channel that unavoidably cannot correspond to the intent of the sound producer); however, such loss is most probably unnoticeable, especially compared to other distortions inherent in sound reproduction, and to the person's problems from hearing loss.
Personal noise reduction devices can be passive, active or a combination. Passive ear protection includes earplugs or earmuffs which can block noise up to a specific frequency. Earplugs and earmuffs can provide the wearer with 10 dB to 40 dB of attenuation. However, use of earplugs is only effective if the users have been educated and use them properly; without proper use, protection falls far below manufacturer ratings. Higher consistency of performance has been found with custom-molded earplugs. Because of their ease of use without education, and ease of application or removal, earmuffs have more consistency with both compliance and noise attenuation. Active ear protection (electronic pass-through hearing protection devices or EPHPs) electronically filter out noises of specific frequencies or decibels while allowing the remaining noise to pass through.
Treatment for aphasias is generally individualized, focusing on specific language and communication improvements, and regular exercise with communication tasks. Regular therapy for conduction aphasics has been shown to result in steady improvement on the Western Aphasia Battery. However, conduction aphasia is a mild aphasia, and conduction aphasics score highly on the WAB at baseline.
APD is a difficult disorder to detect and diagnose. The subjective symptoms that lead to an evaluation for APD include an intermittent inability to process verbal information, leading the person to guess to fill in the processing gaps. There may also be disproportionate problems with decoding speech in noisy environments.
APD has been defined anatomically in terms of the integrity of the auditory areas of the nervous system. However, children with symptoms of APD typically have no evidence of neurological disease and the diagnosis is made on the basis of performance on behavioral auditory tests. Auditory processing is "what we do with what we hear", and in APD there is a mismatch between peripheral hearing ability (which is typically normal) and ability to interpret or discriminate sounds. Thus in those with no signs of neurological impairment, APD is diagnosed on the basis of auditory tests. There is, however, no consensus as to which tests should be used for diagnosis, as evidenced by the succession of task force reports that have appeared in recent years. The first of these occurred in 1996. This was followed by a conference organized by the American Academy of Audiology. Experts attempting to define diagnostic criteria have to grapple with the problem that a child may do poorly on an auditory test for reasons other than poor auditory perception: for instance, failure could be due to inattention, difficulty in coping with task demands, or limited language ability. In an attempt to rule out at least some of these factors, the American Academy of Audiology conference explicitly advocated that for APD to be diagnosed, the child must have a modality-specific problem, i.e. affecting auditory but not visual processing. However, an ASHA committee subsequently rejected modality-specificity as a defining characteristic of auditory processing disorders.
While there is no cure, most people with tinnitus get used to it over time; for a minority, it remains a significant problem.
If the examination reveals a bruit (sound due to turbulent blood flow), imaging studies such as transcranial doppler (TCD) or magnetic resonance angiography (MRA) should be performed.
In case of infection or inflammation, blood or other body fluids may be submitted for laboratory analysis.
Spatial hearing loss can be diagnosed using the Listening in Spatialized Noise – Sentences test (LiSN-S), which was designed to assess the ability of children with central auditory processing disorder (CAPD) to understand speech in background noise. The LiSN-S allows audiologists to measure how well a person uses spatial (and pitch information) to understand speech in noise. Inability to use spatial information has been found to be a leading cause of CAPD in children.
Test participants repeat a series of target sentences which are presented simultaneously with competing speech. The listener's speech reception threshold (SRT) for target sentences is calculated using an adaptive procedure. The targets are perceived as coming from in front of the listener whereas the distracters vary according to where they are perceived spatially (either directly in front or either side of the listener). The vocal identity of the distracters also varies (either the same as, or different from, the speaker of the target sentences).
Performance on the LISN-S is evaluated by comparing listeners' performances across four listening conditions, generating two SRT measures and three "advantage" measures. The advantage measures represent the benefit in dB gained when either talker, spatial, or both talker and spatial cues are available to the listener. The use of advantage measures minimizes the influence of higher order skills on test performance. This serves to control for the inevitable differences that exist between individuals in functions such as language or memory.
Dichotic listening tests can be used to measure the efficacy of the attentional control of cochlear inhibition and the inter-hemispheric transfer of auditory information. Dichotic listening performance typically increases (and the right-ear advantage decreases) with the development of the Corpus Callosum (CC), peaking before the fourth decade. During middle age and older the auditory system ages, the CC reduces in size, and dichotic listening becomes worse, primarily in the left ear. Dichotic listening tests typically involve two different auditory stimuli (usually speech) presented simultaneously, one to each ear, using a set of headphones. Participants are asked to attend to one or (in a divided-attention test) both of the messages.
The activity of the medial olivocochlear bundle (MOC) and its inhibition of cochlear gain can be measured using a Distortion Product Otoacoustic Emission (DPOE) recording method. This involves the contralateral presentation of broadband noise and the measurement of both DPOAE amplitudes and the latency of onset of DPOAE suppression. DPOAE suppression is significantly affected by age and becomes difficult to detect by approximately 50 years of age.
Given the unknown nature of MES, treatments have been largely dependent on an individual basis. Treatments can vary from being as little as self-reassurance to pharmaceutical medications.
Medications can be helpful, such as antipsychotics, benzodiazepines or antiepileptics, but there is very limited evidence for this. Some case studies have found that switching to a prednisolone steroid after a betamethasone steroid which caused MES helped alleviate hallucinations or the use of the acetylcholinesterase inhibitor, Donepezil, have also found that it successfully treated an individual's MES. However, because of the heterogeneous etiology, these methods cannot be applied as general treatment.
Other than treatment by medicinal means, individuals have also successfully alleviated musical hallucinations by cochlear implants, listening to different songs via an external source, or by attempting to block them through mental effort, depending on how severe their condition is.
Hearing loss is generally measured by playing generated or recorded sounds, and determining whether the person can hear them. Hearing sensitivity varies according to the frequency of sounds. To take this into account, hearing sensitivity can be measured for a range of frequencies and plotted on an audiogram.
Another method for quantifying hearing loss is a speech-in-noise test. As the name implies, a speech-in-noise test gives an indication of how well one can understand speech in a noisy environment. A person with a hearing loss will often be less able to understand speech, especially in noisy conditions. This is especially true for people who have a sensorineural loss – which is by far the most common type of hearing loss. As such, speech-in-noise tests can provide valuable information about a person's hearing ability, and can be used to detect the presence of a sensorineural hearing loss. A recently developed digit-triple speech-in-noise test may be a more efficient screening test.
Otoacoustic emissions test is an objective hearing test that may be administered to toddlers and children too young to cooperate in a conventional hearing test. The test is also useful in older children and adults.
Auditory brainstem response testing is an electrophysiological test used to test for hearing deficits caused by pathology within the ear, the cochlear nerve and also within the brainstem. This test can be used to identify delay in the conduction of neural impulses due to tumours or inflammation but can also be an objective test of hearing thresholds. Other electrophysiological tests, such as cortical evoked responses, can look at the hearing pathway up to the level of the auditory cortex.
Psychopharmacological treatments include anti-psychotic medications. Psychology research shows that first step in treatment is for the patient to realize that the voices they hear are creation of their own mind. This realization is argued to allow patients to reclaim a measure of control over their lives. Some additional psychological interventions might allow for the process of controlling these phenomena of auditory hallucinations but more research is needed.