**4. Diagnostics and clinical presentation of the presbycusis**

In the middle of the last century, Schuknecht described four forms of the presbycusis: (1) sensory (caused by gradual degeneration of sensorineural elements of the inner ear); (2) neural (determined by the cell reduction in the spiral ganglion, auditory nerve fibers, and central auditory pathways); (3) metabolic (associated with atrophic changes in the stria vascularis); and (4) cochlear conductive or mechanical (associated with the process of the basal membrane thickening and loss of its elasticity). According to the author, all these forms manifest in increased tonal thresholds, and the neural one also manifests in the impaired speech intelligibility [12]. CAPD is shown to join the peripheral disorders with the aging process, so they also contribute to the presbycusis [28]. One of the keys of solving presbycusis problem is to define the proportion of peripheral and central disorders. Currently, potential role of disorders at all levels of the auditory system is taken into account, and it is realized as an integrated functional system and taken into consideration while understanding the age-related involutional hearing loss pathogenesis [29].

#### **4.1. Asking about complaints and anamnesis**

of different brain areas and provides neurotransmission. Studies performed on mice and humans showed that gene GRM7 is highly active in the hair cells and the spiral ganglion cells of the inner ear. The glutamate is very toxic in high concentration. Its overexciting results in neuron disruption. The excess amount of the glutamate is suspected to cause a hearing loss in twins as the study authors considered. Genetic analysis showed that after getting "protein casts" with certain variations in a gene GRM7 improperly operating glutamate receptor was obtained. It can result in the amino acid storage in the synaptic fissure and damage of the

Of the genetic point of view, presbycusis is the complex pathology. In the case of monogenic disease, a simple mutation is enough to cause a clinical onset/presentation. This type of disease is easy to determine. Meanwhile, in the case of complex genetic disorder, the interaction between genetic and environmental factors is obligatory, and the only factor is not enough for disease manifestation. In the case of genetic predisposition, a degree of hearing loss and a duration of hearing impairment depend on the summary of ototoxic factors, environmental noise during lifetime, as well as acquired diseases, changes of the blood quilts, and other factors contributing to hearing loss progression [19]. These studies are considered to define various factors that influence on the presbycusis development and to determine a degree of hearing disorder in aged and senile periods. They are still significant and must result in devel-

Thus, all abovementioned endo- and exogenous factors that are presented throughout the lifetime are considered to contribute to hearing disorder development in aged and senile periods. Nevertheless, hearing impairment does not occur in everyone and is affected by harmful factors. The role of the atherosclerosis in the age-related hearing loss development has been studied since the middle of the last century. Does the severity of the atherosclerosis and the cochlear dysfunction correlate? Some authors confirm the presence of this correlation between these pathologies [20, 21]. A close interrelation between hearing loss and high serum cholesterol levels is shown in several studies, and the dependence of hearing function on some other atherogenic lipid levels in the blood is found. Inverse correlation of high significance between high-density lipoproteins (HDL) level of the peripheral blood and hearing acuity at the frequency of 4 kHz was revealed [22]. Morphological and functional damages of the cochlea and their correlations with hyperlipidemia, atherosclerosis, and endothelial dysfunction in mice

Increased blood viscosity is known to influence a SNHL development. Hildesheimer et al. examined a group of 33 patients with SNHL with unknown cause; a high-blood viscosity was revealed in many of them, which was interpreted by the authors as a possible etiologic factor of SNHL [24]. Other authors also suggest that rheological properties of the blood and characteristics of the red blood cells can be considered to be a SNHL development risk factor

In the majority of countries, women are registered to have longer lifespan than men that is explained by the biological distinguishing features of the female organism and differences of the atherosclerosis development process in people of different sex [26]. This mismatch has to be taken into account in the study of presbycusis problem. Efimova performed a complex

outer and the inner hair cells in the cochlea [18].

66 Gerontology

are described in studies of Guo et al. [23].

in all patients [25].

oping standards for prognosticating and preventing this pathology.

To diagnose an age-related hearing loss and to determine all risk factors of rapid hearing loss progression complete examination is necessary to begin with history taking (anamnesis), complex audiologic examination using instrumental methods in order to identify a level of a disorder, and finally, biochemical blood tests and general practitioner and neurologist consultations. All these examinations should be performed in the morning in kindly calm and comfortable conditions. The total duration of the audiological examination should not exceed 60 minutes to avoid the fatigue of a patient and loss of his attention.

While collecting a medical history, the absence of any reasons of hearing loss except of the age is noted. These patients do not have any serious somatic illnesses, middle ear pathology, professional noisy environment, or other determined reasons of the impaired hearing. Genetic factors and hearing loss duration should be taken into account while analyzing an anamnesis. Patients with presbycusis commonly cannot determine exactly the onset time of hearing loss due to its gradual progression. The early periods of hearing impairment often remain unnoticed for a patient; meanwhile, in this period, we expect the maximal effectiveness of a therapy. That is why annual prophylactic audiologic examinations of people older than 60 years of age seem to be rational.

and so on [3, 33]. However, as far as in the middle of the last century, an age-related hearing loss was already considered to be the primary consequence of degenerative alterations in sound perceptive part of the ear. The main disorders are suggested to take place in the cochlear

Characteristics of Hearing in Elderly People http://dx.doi.org/10.5772/intechopen.75435 69

Changes of the spiral organ neuroepithelial elements play a leading role in the age-related hearing loss development. But according to some authors, isolated hair cell damage cannot be the only reason of selective high frequencies affected impairment in older age [34]. Involutional and dystrophic changes in the cochlea can be primary or secondary, and it is associated with blood vessel dysfunctions [35]. The reduced number of bipolar cells of the spiral ganglion can be named the steadiest morphologic manifestation of the cochlear aging in humans and animals. Changes of the auditory nerve also play a certain role in the presbycusis

CAPD occurs very often in elderly or senile persons, reaching up to 80% and contributing to the age-related hearing loss [28]. Stach et al. revealed CAPD symptoms in 70% of adults older than 60 years of age, and its occurrence increases with aging: adults of 50–54 years old had CAPD in 17% of cases; meanwhile, adults older than 80 years old had CAPD in 95% of cases [37]. According to Golovanova et al., 31% of elderly patients with normal hearing thresholds complained of hearing impairment, which was explained by the authors as impaired speech intelligibility caused by central auditory pathway dysfunction [38]. Australian investigators, Golding et al., also confirm the increase of CAPD occurrence associated with aging and note the prevalence of men with this pathology [39]. The difficulties of the occurrence of CAPD assessment are associated either with similarity of its symptoms with other pathologies (cognitive disorders, attention deficit, memory impairments, etc.) or with the absence of any stan-

Audiologic methods of evaluation of the central auditory pathway functioning are divided into behavioral (subjective) and objective. Subjective methods are subdivided into verbal and nonverbal methods. Advantages of speech tests are associated with their social significance, the ability to use them both for identifying a level of hearing pathology and for hearing aid fitting. The following speech tests are advised to use by the American work group on CAPD: (1) monaural low redundant; (2) dichotic; and (3) tests of binaural interaction [40]. The first group of tests is believed to be sensitive to auditory cortical disorders, the second is sensitive to dysfunctions of interhemisherical connections, the third is sensitive to the dysfunctions of

Monaural low redundant speech tests evaluate the ability of the auditory system for auditory closure. There are tests with speech signals passed through filters with different cutoff frequencies, signals with distorted temporal characteristics, and tests with speech in background noise. In the tests mentioned above, the auditory closure (the ability to understand a whole word or phrase when a part of them is missing) or the ability to recognize signals in background noise are assessed [28, 32]. While testing with speech in background noise, a speech signal is presented simultaneously with a masker (different types of noise or speech signals). For Russian

higher auditory centers or, according to some authors, to brain stem damages [41].

membranes, which become rigid, thicken, and lose their form as aging progresses [29].

development [36].

**4.3. The evaluation of central auditory pathways**

dards of this disorder diagnostics.

#### **4.2. Evaluation of the peripheral part of the hearing system**

The first step of audiological examination is the peripheral part of the auditory system functioning evaluation. Subjective examination (pure tone audiometry for auditory threshold assessment, speech audiometry, and psychoacoustic tests for recruitment identification) and objective examination (tympanometry and acoustic reflex testing) must be listed as the main methods.

Symmetric binaural pure tone audiogram with flat loss toward high frequencies is typical for patients with presbycusis. Finding out the patient's age, we are able to suggest a degree of hearing loss properly for "normal" age-related hearing loss. Commonly, hearing in women with physiologic presbycusis gradually impairs and reaches the borderline with the mild hearing loss toward 60 years old [3, 27]. The mild hearing loss was detected in 67.9% of women with presbycusis from 60 to 74 years old. The loudness recruitment phenomenon is usually presented in the case of peripheral forms of SNHL. It is the sign of damaged neuroepithelial structures of the cochlea, especially the outer hair cells. Recruitment results in exaggeration of sound perception. Even though there is only a small increase in the noise level, sound may seem to be much louder, can be distorted, and cause a severe discomfort. The measurement of an uncomfortable loudness level is one of the simplest and most informative methods to detect recruitment [30, 31].

Speech audiometry is an issue of high significance among subjective methods of aged people examination. In cases of peripheral SNHL, especially with steeply sloping audiograms or the recruitment presence, the intelligibility usually does not exceed 70–80%. If monaural intelligibility in patient with mild or moderate hearing loss is less than 50%, CAPD can be suspected. It is due to the fact that pathology of central auditory pathways is responsible for the conversion, encoding, processing, and recognizing the speech signals. CAPD leads to the appearance of additional distortions caused by impaired binaural interaction, threshold and loudness adaptation, temporal analysis, and so on. Significantly reduced intelligibility with comparatively good tonal thresholds is defined as of tonal and speech hearing dissociation (phonemic regression); age-related hearing loss often manifests this way [27, 28, 31, 32].

Impedancemetry has to be included into the list of obligatory objective methods using patient's examination. Tympanometry evaluates the middle ear condition. Age-related alterations can be observed in both the sound conductive and receptive parts of the auditory system. Sometimes the external auditory canal narrows in the isthmus area and collapses, and the epithelial migration decreases. The eardrum in aged people thickens and dims. Lipid deposits appear around the handle of the malleus and the fibrous tympanic ring. In some cases, the eardrum does not thicken but on the contrary atrophies. Age-related changes of the middle ear matter a lot and manifest in ankylosis of the joints of auditory ossicles with the development of adhesions among the eardrum, auditory ossicles and promontorium, ossification of the circular ligament, and so on [3, 33]. However, as far as in the middle of the last century, an age-related hearing loss was already considered to be the primary consequence of degenerative alterations in sound perceptive part of the ear. The main disorders are suggested to take place in the cochlear membranes, which become rigid, thicken, and lose their form as aging progresses [29].

Changes of the spiral organ neuroepithelial elements play a leading role in the age-related hearing loss development. But according to some authors, isolated hair cell damage cannot be the only reason of selective high frequencies affected impairment in older age [34]. Involutional and dystrophic changes in the cochlea can be primary or secondary, and it is associated with blood vessel dysfunctions [35]. The reduced number of bipolar cells of the spiral ganglion can be named the steadiest morphologic manifestation of the cochlear aging in humans and animals. Changes of the auditory nerve also play a certain role in the presbycusis development [36].

#### **4.3. The evaluation of central auditory pathways**

anamnesis. Patients with presbycusis commonly cannot determine exactly the onset time of hearing loss due to its gradual progression. The early periods of hearing impairment often remain unnoticed for a patient; meanwhile, in this period, we expect the maximal effectiveness of a therapy. That is why annual prophylactic audiologic examinations of people older

The first step of audiological examination is the peripheral part of the auditory system functioning evaluation. Subjective examination (pure tone audiometry for auditory threshold assessment, speech audiometry, and psychoacoustic tests for recruitment identification) and objective examination (tympanometry and acoustic reflex testing) must be listed as the main methods.

Symmetric binaural pure tone audiogram with flat loss toward high frequencies is typical for patients with presbycusis. Finding out the patient's age, we are able to suggest a degree of hearing loss properly for "normal" age-related hearing loss. Commonly, hearing in women with physiologic presbycusis gradually impairs and reaches the borderline with the mild hearing loss toward 60 years old [3, 27]. The mild hearing loss was detected in 67.9% of women with presbycusis from 60 to 74 years old. The loudness recruitment phenomenon is usually presented in the case of peripheral forms of SNHL. It is the sign of damaged neuroepithelial structures of the cochlea, especially the outer hair cells. Recruitment results in exaggeration of sound perception. Even though there is only a small increase in the noise level, sound may seem to be much louder, can be distorted, and cause a severe discomfort. The measurement of an uncomfortable loudness level is one of the simplest and most informative methods to detect

Speech audiometry is an issue of high significance among subjective methods of aged people examination. In cases of peripheral SNHL, especially with steeply sloping audiograms or the recruitment presence, the intelligibility usually does not exceed 70–80%. If monaural intelligibility in patient with mild or moderate hearing loss is less than 50%, CAPD can be suspected. It is due to the fact that pathology of central auditory pathways is responsible for the conversion, encoding, processing, and recognizing the speech signals. CAPD leads to the appearance of additional distortions caused by impaired binaural interaction, threshold and loudness adaptation, temporal analysis, and so on. Significantly reduced intelligibility with comparatively good tonal thresholds is defined as of tonal and speech hearing dissociation (phonemic regression); age-related hearing loss often manifests this way [27, 28, 31, 32].

Impedancemetry has to be included into the list of obligatory objective methods using patient's examination. Tympanometry evaluates the middle ear condition. Age-related alterations can be observed in both the sound conductive and receptive parts of the auditory system. Sometimes the external auditory canal narrows in the isthmus area and collapses, and the epithelial migration decreases. The eardrum in aged people thickens and dims. Lipid deposits appear around the handle of the malleus and the fibrous tympanic ring. In some cases, the eardrum does not thicken but on the contrary atrophies. Age-related changes of the middle ear matter a lot and manifest in ankylosis of the joints of auditory ossicles with the development of adhesions among the eardrum, auditory ossicles and promontorium, ossification of the circular ligament,

than 60 years of age seem to be rational.

68 Gerontology

recruitment [30, 31].

**4.2. Evaluation of the peripheral part of the hearing system**

CAPD occurs very often in elderly or senile persons, reaching up to 80% and contributing to the age-related hearing loss [28]. Stach et al. revealed CAPD symptoms in 70% of adults older than 60 years of age, and its occurrence increases with aging: adults of 50–54 years old had CAPD in 17% of cases; meanwhile, adults older than 80 years old had CAPD in 95% of cases [37]. According to Golovanova et al., 31% of elderly patients with normal hearing thresholds complained of hearing impairment, which was explained by the authors as impaired speech intelligibility caused by central auditory pathway dysfunction [38]. Australian investigators, Golding et al., also confirm the increase of CAPD occurrence associated with aging and note the prevalence of men with this pathology [39]. The difficulties of the occurrence of CAPD assessment are associated either with similarity of its symptoms with other pathologies (cognitive disorders, attention deficit, memory impairments, etc.) or with the absence of any standards of this disorder diagnostics.

Audiologic methods of evaluation of the central auditory pathway functioning are divided into behavioral (subjective) and objective. Subjective methods are subdivided into verbal and nonverbal methods. Advantages of speech tests are associated with their social significance, the ability to use them both for identifying a level of hearing pathology and for hearing aid fitting. The following speech tests are advised to use by the American work group on CAPD: (1) monaural low redundant; (2) dichotic; and (3) tests of binaural interaction [40]. The first group of tests is believed to be sensitive to auditory cortical disorders, the second is sensitive to dysfunctions of interhemisherical connections, the third is sensitive to the dysfunctions of higher auditory centers or, according to some authors, to brain stem damages [41].

Monaural low redundant speech tests evaluate the ability of the auditory system for auditory closure. There are tests with speech signals passed through filters with different cutoff frequencies, signals with distorted temporal characteristics, and tests with speech in background noise. In the tests mentioned above, the auditory closure (the ability to understand a whole word or phrase when a part of them is missing) or the ability to recognize signals in background noise are assessed [28, 32]. While testing with speech in background noise, a speech signal is presented simultaneously with a masker (different types of noise or speech signals). For Russian language, Prof. Lopotko [30] created the Russian speech audiometric express test, during which polysyllable words are presented in the background of different noises (white noise, noise of transport, etc.). In the last year, the matrix sentence test has become rather popular, aimed to evaluate phrases intelligibility in background noise, and approbated for many European languages including Russian (Russian matrix sentence test—RuMatrix) [42]. In the presence of CAPD, intelligibility of distorted speech or speech in background noise is very poor [28].

negativity. At the moment, the unique criteria to include any type of AEP in the test battery

Characteristics of Hearing in Elderly People http://dx.doi.org/10.5772/intechopen.75435 71

Concluding the aforementioned, audiological methods for CAPD diagnosing can be divided into the following ways: speech tests (monaural low redundant, dichotic, and binaural interaction); tests assessing temporal processing; and electrophysiologic tests. Tests to perform should be chosen individually based on patient's complaints and anamnesis. Both verbal and nonverbal tests should be included. The mentioned division of the tests does not mean that tests from all groups must be used. The minimally necessary number of tests is recommended. The use of electrophysiologic tests is determined by the lack of possibility to use behavioral tests or the lack of their accuracy [40, 51]. Thus, the audiologic examination of a patient with presbycusis includes the following steps: (1) collection of complaints, anamnesis, and ENT examination; (2) pure tonal threshold audiometry in silence; (3) impedancemetry; and (4) CAPD tests.

A constant increase in number of elderly and senile people, greater demands on the quality of life in contemporary society, along with extended possibilities of audiological examination dictates a necessity to seek new approaches to the problem of age-related hearing loss. Identification of a pathology level in the auditory system with presbycusis matters a lot while

Hearing aid fitting is the only possibility to compensate hearing loss in elderly people in the majority of cases. With the technical progress, hearing aids (HAs) become more complex devices satisfying users' needs, but often HAs do not meet high expectations placed upon it. There are data that only from 6 to 40% of patients with hearing loss use a HA [52, 53]. A number of patients completely satisfied by HA fitting results are about 20%; in elderly people, this percent is even lower, which is associated with several distinguishing features of this group [31, 54, 55]. Memory disorders, impaired ability to capture new information, cognitive disorders, impaired vision, degraded fine motor skills, and the presence of co-morbidities along with specific alterations of auditory perception are among these features [56]. Meanwhile, the refuse of patients with hearing loss to use HA is known to disturb socialization significantly, to lead to social isolation, to intensify cognitive disorders, to reduce the safety of vital activity, and to cause the essential deterioration of quality of life [57]. To evaluate the effectiveness of HA, the speech audiometry in free field is commonly used in adults along with questionnaires [58]. Together with medical parameters, social criteria (ability to practice their profession, to communicate in family without any difficulties, to lead an active social life, etc.) are evaluated. Despite high prevalence of hearing loss, few studies dedicated to the problem of

Low effectiveness of HA fitting in elderly and senile patients was shown in our study by results of speech audiometry in 26 (21%) of 125 patients (percent of polysyllabic words intelligibility in quiet with HA was less than 70%). The analysis of results of an audiological examination allowed to conclude that the main factor reducing the effectiveness of HA use in elderly patients

choosing a further tactics of treatment and hearing aid fitting.

**5. Rehabilitation of patients with presbycusis**

HA effectiveness exist up to the moment [59].

for revealing CAPD do not exist.

In the dichotic tests, different speech signals, for example, monosyllable words, are presented through headphones to each ear simultaneously. In these tests, binaural integration (when a patient is instructed to repeat all signals presented to both ears) and binaural separation (when a patient is instructed to repeat signals presented only to one ear) are assessed. Numerous studies proved that in conditions of competition between right and left auditory channels, an ear that is contralateral to a dominant in the processing of presented signal hemisphere dominates. The majority of people are right-handed, and the speech center is located mainly in the left hemisphere, so the right auditory channel is dominant. This phenomenon is called "the right ear effect." However, the right ear dominance occurs only in 80% of right-handed, while the speech center is located in the left hemisphere in 95% of right-handed people. The dominance of ipsilateral auditory pathways in some people may be the cause of this fact. A large number of dichotic test modifications were suggested as follows: dichotic digit test [43], dichotic sentence identification [44], and so on. Currently, dichotic tests are among the most popular methods to examine interhemispherical asymmetry in healthy people of different ages and in patients with central neural disorders [28, 30, 32].

In tests of binaural interaction, information is presented to each ear not simultaneously but consecutively: one part of a word/phrase is presented to one ear and the other part is presented to another. The ability of a listener to integrate signals and repeat correctly the whole income information is evaluated [41]. An example of the group tests is the audiometry with binaural alternating speech [45]. For English language, the following examples are CVC Fusion Test, during which consonants are presented to one ear, and vowels are presented to another; Spondee Binaural Fusion Test; and so on. [28].

Results of nonverbal CAPD tests are less influenced by linguistic knowledge of a patient, which is their advantage, but to perform many of them special not commercially manufactured equipment is often required [46]. One of the crucial methods of temporal processing evaluation is the Random Gap Detection Test (RGDT). It is sensitive to cortical pathologies, especially of the left hemisphere. During this test, signals (pure tones and broadband noise) with inserted pauses are presented through headphones at a comfortable loudness level [28, 47]. In the last year, indications to use subjective test diagnosing CAPD are expanded. Impaired speech intelligibility because of CAPD is proved to be one of the predictors of Alzheimer's disease and dementia. To detect at-risk groups, some authors suggest a number of behavioral tests with high sensitivity to subclinical cognitive deficit comparing to screening cognitive tests [48–50].

Electrophysiologic (objective) audiological tests include auditory evoked potentials (AEPs), which are divided into several types by localization of generators and time of onset: cochlear potentials (are registered during cochleography), short latency (brainstem) auditory evoked potentials, middle latency AEP, long latency (cortical) AEP, cognitive potentials, and mismatch negativity. At the moment, the unique criteria to include any type of AEP in the test battery for revealing CAPD do not exist.

Concluding the aforementioned, audiological methods for CAPD diagnosing can be divided into the following ways: speech tests (monaural low redundant, dichotic, and binaural interaction); tests assessing temporal processing; and electrophysiologic tests. Tests to perform should be chosen individually based on patient's complaints and anamnesis. Both verbal and nonverbal tests should be included. The mentioned division of the tests does not mean that tests from all groups must be used. The minimally necessary number of tests is recommended. The use of electrophysiologic tests is determined by the lack of possibility to use behavioral tests or the lack of their accuracy [40, 51]. Thus, the audiologic examination of a patient with presbycusis includes the following steps: (1) collection of complaints, anamnesis, and ENT examination; (2) pure tonal threshold audiometry in silence; (3) impedancemetry; and (4) CAPD tests.

A constant increase in number of elderly and senile people, greater demands on the quality of life in contemporary society, along with extended possibilities of audiological examination dictates a necessity to seek new approaches to the problem of age-related hearing loss. Identification of a pathology level in the auditory system with presbycusis matters a lot while choosing a further tactics of treatment and hearing aid fitting.
