**5. Rehabilitation of patients with presbycusis**

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].

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

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

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

ages and in patients with central neural disorders [28, 30, 32].

70 Gerontology

another; Spondee Binaural Fusion Test; and so on. [28].

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 HA effectiveness exist up to the moment [59].

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 was the presence and a degree of CAPD. Studies of other authors confirm this fact [28, 60]. With alterations of the retrocochlear structures, which are often associated with presbycusis, a person's ability to process and differentiate temporal and spectral properties of acoustic signals is violated, especially in conditions of perceiving speech in background noise [60].

Generally, these two approaches complement each other and must be applied together to reach maximum positive results, to improve speech intelligibility, and to compensate a residuary deficit [65]. Concrete rehabilitation plan must be worked out individually depending on deficit profile of a patient, his lifestyle, social and communicative needs, presence of comorbidities,and so on. The concept of the auditory training as acoustic stimulation has been known a few centuries. At the end of 1990, first confirmations of the influence of auditory deprivation on the auditory system and proofs of plasticity inherent to the brain appeared, so

Characteristics of Hearing in Elderly People http://dx.doi.org/10.5772/intechopen.75435 73

Results of last studies definitively proved that plasticity was inherent to the brain, that is, the ability of the cortex and lower levels to reorganize, and these modifications were manifested in behavioral changes [66, 67]. Although the plasticity of the brain is maximum in childhood, the ability to reorganize in the response to education persists in the mature CNS as well [68]. The auditory training leads to the reorganization of the cortex and brainstem and the increase in effectiveness of the synaptic transmission and in density of the neural tissue [66, 67, 69, 70]. Even rather peripheral processes such as determination of signal pitch can be altered during the training [71]. Cortical changes stimulated by the auditory training invade rather broad areas and remain for a long time [65]. They include four types of cortical reorganization: (1) expansion of maps, that is, areas responsible for a trained function; (2) a compensatory transmission of performing a trained function into another cortical area; (3) cross modal reorganization with involvement of cortical areas receiving an input signal from other sensory modalities; and (4) adaptation of homologous regions, that is, activation in areas in homolo-

Studies on animal models proved that auditory stimulation induces alterations of inherent neural substrate. For example, tonotopic reorganization of the auditory cortex was revealed in monkeys after intensive frequency discrimination tasks. The cortical representation, the sharpness of tuning, and the latency of the response were greater for the behaviorally relevant frequencies of trained monkeys when compared to the same frequencies of control monkeys [65]. Experiences with rats showed that training-induced improvements occurred in the auditory cortex even if a damage (an impact of noise in the experiences) was done in childhood. This proves the possibility of improvement, or maybe restoration, of auditory function in adult rats even after a long time after the initial damage to the auditory cortex [73]. Another study on rats showed that the age-related deficit in distinguishing sound characteristics could also be restored by the intensive auditory training, and not only functional but also structural changes in the auditory cortex resulted from the training [74]. The human auditory system is

Before studying patients with hearing loss, the auditory training was approbated in patients with normal hearing. Positive results of the training in persons with normal functioning of the auditory system (both peripheral and central) were shown: the improved results of behavioral and electrophysiological tests were observed after the auditory training to distinguish sound stimuli consonant-vowel [75, 76]. Significant improvement of speech intelligibility was observed in young persons with normal hearing after the auditory training with multiple tasks (speech in noise and accelerated speech) for 8 weeks. The improved results of behavioral tests

assumed to undergo similar changes in conditions of sound stimulation.

the principles of the auditory training regained its development [65].

gous regions of the contralateral hemisphere [72].

Modern HAs are known to solve the problems of peripheral hearing loss but often not the ones of impaired speech intelligibility. Besides, HAs providing enough loudness of speech signal do not always improve signal-to-noise ratio [61], which disturb good intelligibility. Up-to-date technologies, for example, systems of noise reduction and differentiation between speech and noise, directional microphones, and the presence of various listening programs in one HA, allow a user to increase speech intelligibility with HA [62]. According to our study to increase the effectiveness of HA use by elderly patients, a complex of measures is needed including special audiological examination, therapy aimed at correction of CAPD, and HA fitting with consideration of individual features of a patient's auditory system.

Revealing CAPD before HA fitting allows an audiologist to prescribe adequate treatment, to warn a patient and his relatives about possible difficulties with HA use, to avoid excessive expectations from HA use, and to plan rehabilitation after HA fitting. To diagnose CAPD, all tests mentioned above are not necessary to perform, although all of them are performed with the use of standard equipment and do not require a lot of time. A percent of monosyllabic words intelligibility in quiet at a comfortable loudness level could serve as an express criterion to prognosticate an effectiveness of HA. Our study showed that with this percent being less than 60%, the risk of poor results from HA fitting significantly increases. A long adaptation to HA, involving not only an audiologist but also a speech therapist and a psychologist, is often required. The aim of such work is the successful use of a HA, so that in older hearing impaired patients social contacts expand, communication skills improve, and self-esteem and overall quality of life increase [59, 60].

At the moment the designed pharmacological treatment of impaired speech intelligibility associated with CAPD does not exist, this problem is being actively studied [27, 63, 64]. Despite the absence of significant success in creation of drugs for restoring speech intelligibility, improving speech signal processing in central auditory pathways is possible, thanks to the auditory training that helps to correct CAPD.

The auditory training is the complex of acoustic settings and tasks created to activate the auditory and related systems and to cause positive changes of neuronal activity and related auditory behavior. Two types of the auditory training are distinguished: (1) "bottom-up" approach (from the periphery to central parts, due to incoming sound signal) includes the improved audibility and sound quality through the use of hearing aids, FM systems and optimization of room acoustics, as well as sessions with a speech therapist to correct temporal and frequency processing, sensitivity to changes of loudness, and so on [65] and (2) "top-down" approach (from central parts to periphery involving higher functions of central nervous system) combines linguistic, cognitive, and metacognitive strategies of learning and includes special complexes to train the auditory attention, memory, linguistic and cognitive functions, musical education, and learning foreign languages.

Generally, these two approaches complement each other and must be applied together to reach maximum positive results, to improve speech intelligibility, and to compensate a residuary deficit [65]. Concrete rehabilitation plan must be worked out individually depending on deficit profile of a patient, his lifestyle, social and communicative needs, presence of comorbidities,and so on. The concept of the auditory training as acoustic stimulation has been known a few centuries. At the end of 1990, first confirmations of the influence of auditory deprivation on the auditory system and proofs of plasticity inherent to the brain appeared, so the principles of the auditory training regained its development [65].

was the presence and a degree of CAPD. Studies of other authors confirm this fact [28, 60]. With alterations of the retrocochlear structures, which are often associated with presbycusis, a person's ability to process and differentiate temporal and spectral properties of acoustic signals is violated, especially in conditions of perceiving speech in background noise [60].

Modern HAs are known to solve the problems of peripheral hearing loss but often not the ones of impaired speech intelligibility. Besides, HAs providing enough loudness of speech signal do not always improve signal-to-noise ratio [61], which disturb good intelligibility. Up-to-date technologies, for example, systems of noise reduction and differentiation between speech and noise, directional microphones, and the presence of various listening programs in one HA, allow a user to increase speech intelligibility with HA [62]. According to our study to increase the effectiveness of HA use by elderly patients, a complex of measures is needed including special audiological examination, therapy aimed at correction of CAPD, and HA

Revealing CAPD before HA fitting allows an audiologist to prescribe adequate treatment, to warn a patient and his relatives about possible difficulties with HA use, to avoid excessive expectations from HA use, and to plan rehabilitation after HA fitting. To diagnose CAPD, all tests mentioned above are not necessary to perform, although all of them are performed with the use of standard equipment and do not require a lot of time. A percent of monosyllabic words intelligibility in quiet at a comfortable loudness level could serve as an express criterion to prognosticate an effectiveness of HA. Our study showed that with this percent being less than 60%, the risk of poor results from HA fitting significantly increases. A long adaptation to HA, involving not only an audiologist but also a speech therapist and a psychologist, is often required. The aim of such work is the successful use of a HA, so that in older hearing impaired patients social contacts expand, communication skills improve, and self-esteem and

At the moment the designed pharmacological treatment of impaired speech intelligibility associated with CAPD does not exist, this problem is being actively studied [27, 63, 64]. Despite the absence of significant success in creation of drugs for restoring speech intelligibility, improving speech signal processing in central auditory pathways is possible, thanks to

The auditory training is the complex of acoustic settings and tasks created to activate the auditory and related systems and to cause positive changes of neuronal activity and related auditory behavior. Two types of the auditory training are distinguished: (1) "bottom-up" approach (from the periphery to central parts, due to incoming sound signal) includes the improved audibility and sound quality through the use of hearing aids, FM systems and optimization of room acoustics, as well as sessions with a speech therapist to correct temporal and frequency processing, sensitivity to changes of loudness, and so on [65] and (2) "top-down" approach (from central parts to periphery involving higher functions of central nervous system) combines linguistic, cognitive, and metacognitive strategies of learning and includes special complexes to train the auditory attention, memory, linguistic and cognitive functions,

fitting with consideration of individual features of a patient's auditory system.

overall quality of life increase [59, 60].

72 Gerontology

the auditory training that helps to correct CAPD.

musical education, and learning foreign languages.

Results of last studies definitively proved that plasticity was inherent to the brain, that is, the ability of the cortex and lower levels to reorganize, and these modifications were manifested in behavioral changes [66, 67]. Although the plasticity of the brain is maximum in childhood, the ability to reorganize in the response to education persists in the mature CNS as well [68]. The auditory training leads to the reorganization of the cortex and brainstem and the increase in effectiveness of the synaptic transmission and in density of the neural tissue [66, 67, 69, 70]. Even rather peripheral processes such as determination of signal pitch can be altered during the training [71]. Cortical changes stimulated by the auditory training invade rather broad areas and remain for a long time [65]. They include four types of cortical reorganization: (1) expansion of maps, that is, areas responsible for a trained function; (2) a compensatory transmission of performing a trained function into another cortical area; (3) cross modal reorganization with involvement of cortical areas receiving an input signal from other sensory modalities; and (4) adaptation of homologous regions, that is, activation in areas in homologous regions of the contralateral hemisphere [72].

Studies on animal models proved that auditory stimulation induces alterations of inherent neural substrate. For example, tonotopic reorganization of the auditory cortex was revealed in monkeys after intensive frequency discrimination tasks. The cortical representation, the sharpness of tuning, and the latency of the response were greater for the behaviorally relevant frequencies of trained monkeys when compared to the same frequencies of control monkeys [65]. Experiences with rats showed that training-induced improvements occurred in the auditory cortex even if a damage (an impact of noise in the experiences) was done in childhood. This proves the possibility of improvement, or maybe restoration, of auditory function in adult rats even after a long time after the initial damage to the auditory cortex [73]. Another study on rats showed that the age-related deficit in distinguishing sound characteristics could also be restored by the intensive auditory training, and not only functional but also structural changes in the auditory cortex resulted from the training [74]. The human auditory system is assumed to undergo similar changes in conditions of sound stimulation.

Before studying patients with hearing loss, the auditory training was approbated in patients with normal hearing. Positive results of the training in persons with normal functioning of the auditory system (both peripheral and central) were shown: the improved results of behavioral and electrophysiological tests were observed after the auditory training to distinguish sound stimuli consonant-vowel [75, 76]. Significant improvement of speech intelligibility was observed in young persons with normal hearing after the auditory training with multiple tasks (speech in noise and accelerated speech) for 8 weeks. The improved results of behavioral tests were confirmed by the increased sharpness of frequency tuning, especially fundamental frequency and the second harmonic [77]. Thus, the auditory training causes the changes in neural activity and improves the neural impulses, which provide coding speech signals [78]. Positive changes of mismatch negativity and increased amplitudes of P1 , N1 , and P<sup>2</sup> were revealed after the training. N1 -P2 potential is considered to reflect early cortical processes associated with stimulus decoding and speech detection. Mismatch negativity reflects later processes including distinguishing of speech stimuli changes. The activity of the superior temporal gyrus and planum polare of the right hemisphere on fMRI had decreased in patients after the auditory training, which reflected the enhanced effectiveness of functioning of these areas and improved ability of auditory perception [79]. Some authors consider these improvements to occur only for the trained sound stimulus, and others consider to spread on other stimuli [80]. Neurons of the auditory cortex, which are selectively tuned to some frequencies or amplitudes, were found to be able to change their selectivity after the behavioral auditory training [81].

Nonverbal training included the following tasks: (1) to distinguish stimuli by pitch with sets of 18 musical sounds of different pitches. Increase of the stimulation complexity—from the set "1 instrument—1 pause" to the set "3 instruments—2 pauses"; (2) to detect silent pause between two sound signals—three variants (tonal signal, noise signal, and vowel); and (3) to

Characteristics of Hearing in Elderly People http://dx.doi.org/10.5772/intechopen.75435 75

Verbal training included the following tasks: (1) to distinguish a rhythmical pattern of 15 sequences of three syllables/phonemes (vowel "A," syllables "MA," and "PA") of different duration or intensity; (2) to perceive acoustically similar words and syllables with a choice of the correct word from 6 to 12 homonyms ("dom-tom" and "gora-kora"); (3) to distinguish syllables with a choice from two syllables ("ba-va" and "ga-da"), in more complex variants from four to eight syllables; and (4) to perceive speech in background speech noise with identifying all vowels presented (eight variants in the set) or words (20 in the set), in the complex variant—to identify the predetermined signal by a speaker's voice (vowels or words spoken

Classes lasted for 60 minutes and were carried out twice a week. The course of the auditory training took 8–10 weeks. A percent of correct answers and time of reaction were compared in the beginning and at the end of the training when analyzing the results. After the training, the significantly improved (p < 0.01) perception of verbal and nonverbal signals was revealed both in young and elderly HA users (a percent of correct answers increased by 24.4 ± 5.2% and 15.3 ± 6.4% accordingly; decrease of time of reaction in the range from 0.4 tо 1.6 seconds). Besides, RuMatrix in quiet and noise, performed with hearing aids in free field before and after the training, was used to assess the effectiveness of the training. Signals were presented from a loudspeaker located at an angle of 0° relatively to a patient's head (frontally) on 1 m distance. The effectiveness of the training was evaluated by calculating the difference between first and last results. Significantly improved speech intelligibility (p < 0.05) both in quiet and in noise was revealed after the training. According to the results of the RuMatrix in quiet, the intensity, at which 50% sentence intelligibility level was achieved, was 44.5 ± 11.4 dB SPL before the training and 43.5 ± 12.5 dB SPL after the training. The difference of the results is significant (р < 0.05). According to the results of the RuMatrix in noise, signal-to-noise ratio, at which 50% sentence intelligibility level was achieved, was 1.5 ± 5.5 dB SNR before the training and −0.33 ± 5.5 dB

SNR after the training. The difference between the results is also significant (р < 0.05).

complication of tasks in the process of each session and from lesson to lesson [82].

Based on the study, improved functioning of the central auditory pathway was shown after the auditory training, so it is appropriate to include it in the rehabilitation of HA users with low speech intelligibility in noise. The following algorithm of the auditory training was designed: (1) the distinction between nonverbal signals with changes in their duration, frequency, and intensity; (2) recognition of speech stimuli of varying complexity, including speech in background noise; and (3) tasks to improve memory. An important aspect of training was a gradual

Improvement of speech intelligibility in elderly patients with SNHL proves that plasticity of the auditory regions of the brain remains possible throughout the life. Stimulation-induced plastic changes in the central auditory pathways were proved by other researchers too [28]. According to some researchers, the decreased latency time and decreased variability between peaks of auditory evoked potentials were revealed in elderly after the course of the auditory

evaluate rhythmic pattern of three signals (long or short).

by male or female voice) in background speech of another speaker.

It can be said that we form our brain as we form our muscles. These data open up new possibilities for rehabilitation, particularly the possibility to train patients' own central resources. Although the compensation of the peripheral deficit (the increased intensity of input signal) dominates in rehabilitation of elderly patients, the role of deficit-specific, intensive auditory training should not be underestimated.

In case of concurrent attention, deficits or intellectual disorder cognitive trainings are also used [65]. Compensatory training belongs to "top-down" approach designed to minimize the impact of auditory processing deficit that persists after the modification of acoustic environment and the auditory training. Compensatory training includes providing information on strategies of communication aimed at strengthening the use of central cognitive resources (linguistic strategies, memory, ability to problem solving, exercises on vocabulary expansion, development of active listening, and training of concentration). General recommendations on lifestyle such as preservation of intellectual activity, maintaining physical activity, minimizing chronic stress, and healthy nutrition are helpful to reduce a risk of development of cognitive deficit [28]. The effectiveness of the auditory training is explained by the fact that neuroplasticity is not completely lost with the aging process, though gradually decreases [60]. The central auditory system in elderly persons preserves its ability for training-induced alterations, which entails the possibility to improve speech intelligibility, especially in noisy environment [65].

In the laboratory of hearing and speech (Saint-Petersburg, Russia), a program of the auditory training with the use of two approaches "bottom-up" and "top-down" was evaluated. The aim of the study was to design an optimal algorithm of the auditory training for adults with SNHL and poor speech intelligibility in noise. Twenty-nine patients, HA users with moderate to moderately severe SNHL and symptoms of CAPD, including poor speech intelligibility in noise, underwent this auditory training: 12 young patients (from 19 to 22 years old) and 17 elderly and senile patients (from 60 to 83 years old). An examination before the training included the pure tonal audiometry, tests evaluating central auditory pathway functioning, and speech audiometry in free field by means of the Russian Matrix sentence test (RUMatrix). The auditory training was conducted individually by a speech therapist and included a distinction between nonverbal and verbal stimuli of varying complexity, as well as tasks to improve memory (e.g., memorizing poetry).

Nonverbal training included the following tasks: (1) to distinguish stimuli by pitch with sets of 18 musical sounds of different pitches. Increase of the stimulation complexity—from the set "1 instrument—1 pause" to the set "3 instruments—2 pauses"; (2) to detect silent pause between two sound signals—three variants (tonal signal, noise signal, and vowel); and (3) to evaluate rhythmic pattern of three signals (long or short).

were confirmed by the increased sharpness of frequency tuning, especially fundamental frequency and the second harmonic [77]. Thus, the auditory training causes the changes in neural activity and improves the neural impulses, which provide coding speech signals [78]. Positive

stimulus decoding and speech detection. Mismatch negativity reflects later processes including distinguishing of speech stimuli changes. The activity of the superior temporal gyrus and planum polare of the right hemisphere on fMRI had decreased in patients after the auditory training, which reflected the enhanced effectiveness of functioning of these areas and improved ability of auditory perception [79]. Some authors consider these improvements to occur only for the trained sound stimulus, and others consider to spread on other stimuli [80]. Neurons of the auditory cortex, which are selectively tuned to some frequencies or amplitudes, were found

It can be said that we form our brain as we form our muscles. These data open up new possibilities for rehabilitation, particularly the possibility to train patients' own central resources. Although the compensation of the peripheral deficit (the increased intensity of input signal) dominates in rehabilitation of elderly patients, the role of deficit-specific, intensive auditory

In case of concurrent attention, deficits or intellectual disorder cognitive trainings are also used [65]. Compensatory training belongs to "top-down" approach designed to minimize the impact of auditory processing deficit that persists after the modification of acoustic environment and the auditory training. Compensatory training includes providing information on strategies of communication aimed at strengthening the use of central cognitive resources (linguistic strategies, memory, ability to problem solving, exercises on vocabulary expansion, development of active listening, and training of concentration). General recommendations on lifestyle such as preservation of intellectual activity, maintaining physical activity, minimizing chronic stress, and healthy nutrition are helpful to reduce a risk of development of cognitive deficit [28]. The effectiveness of the auditory training is explained by the fact that neuroplasticity is not completely lost with the aging process, though gradually decreases [60]. The central auditory system in elderly persons preserves its ability for training-induced alterations, which entails the possibility to improve speech intelligibility, especially in noisy environment [65]. In the laboratory of hearing and speech (Saint-Petersburg, Russia), a program of the auditory training with the use of two approaches "bottom-up" and "top-down" was evaluated. The aim of the study was to design an optimal algorithm of the auditory training for adults with SNHL and poor speech intelligibility in noise. Twenty-nine patients, HA users with moderate to moderately severe SNHL and symptoms of CAPD, including poor speech intelligibility in noise, underwent this auditory training: 12 young patients (from 19 to 22 years old) and 17 elderly and senile patients (from 60 to 83 years old). An examination before the training included the pure tonal audiometry, tests evaluating central auditory pathway functioning, and speech audiometry in free field by means of the Russian Matrix sentence test (RUMatrix). The auditory training was conducted individually by a speech therapist and included a distinction between nonverbal and verbal stimuli of varying complexity, as well as tasks to

to be able to change their selectivity after the behavioral auditory training [81].

, N1

potential is considered to reflect early cortical processes associated with

, and P<sup>2</sup>

were revealed after

changes of mismatch negativity and increased amplitudes of P1

the training. N1

74 Gerontology


training should not be underestimated.

improve memory (e.g., memorizing poetry).

Verbal training included the following tasks: (1) to distinguish a rhythmical pattern of 15 sequences of three syllables/phonemes (vowel "A," syllables "MA," and "PA") of different duration or intensity; (2) to perceive acoustically similar words and syllables with a choice of the correct word from 6 to 12 homonyms ("dom-tom" and "gora-kora"); (3) to distinguish syllables with a choice from two syllables ("ba-va" and "ga-da"), in more complex variants from four to eight syllables; and (4) to perceive speech in background speech noise with identifying all vowels presented (eight variants in the set) or words (20 in the set), in the complex variant—to identify the predetermined signal by a speaker's voice (vowels or words spoken by male or female voice) in background speech of another speaker.

Classes lasted for 60 minutes and were carried out twice a week. The course of the auditory training took 8–10 weeks. A percent of correct answers and time of reaction were compared in the beginning and at the end of the training when analyzing the results. After the training, the significantly improved (p < 0.01) perception of verbal and nonverbal signals was revealed both in young and elderly HA users (a percent of correct answers increased by 24.4 ± 5.2% and 15.3 ± 6.4% accordingly; decrease of time of reaction in the range from 0.4 tо 1.6 seconds). Besides, RuMatrix in quiet and noise, performed with hearing aids in free field before and after the training, was used to assess the effectiveness of the training. Signals were presented from a loudspeaker located at an angle of 0° relatively to a patient's head (frontally) on 1 m distance. The effectiveness of the training was evaluated by calculating the difference between first and last results. Significantly improved speech intelligibility (p < 0.05) both in quiet and in noise was revealed after the training. According to the results of the RuMatrix in quiet, the intensity, at which 50% sentence intelligibility level was achieved, was 44.5 ± 11.4 dB SPL before the training and 43.5 ± 12.5 dB SPL after the training. The difference of the results is significant (р < 0.05). According to the results of the RuMatrix in noise, signal-to-noise ratio, at which 50% sentence intelligibility level was achieved, was 1.5 ± 5.5 dB SNR before the training and −0.33 ± 5.5 dB SNR after the training. The difference between the results is also significant (р < 0.05).

Based on the study, improved functioning of the central auditory pathway was shown after the auditory training, so it is appropriate to include it in the rehabilitation of HA users with low speech intelligibility in noise. The following algorithm of the auditory training was designed: (1) the distinction between nonverbal signals with changes in their duration, frequency, and intensity; (2) recognition of speech stimuli of varying complexity, including speech in background noise; and (3) tasks to improve memory. An important aspect of training was a gradual complication of tasks in the process of each session and from lesson to lesson [82].

Improvement of speech intelligibility in elderly patients with SNHL proves that plasticity of the auditory regions of the brain remains possible throughout the life. Stimulation-induced plastic changes in the central auditory pathways were proved by other researchers too [28]. According to some researchers, the decreased latency time and decreased variability between peaks of auditory evoked potentials were revealed in elderly after the course of the auditory training and accompanied by improved speech intelligibility in noise and short-term memory [28]. As shown by our study, improvement of neuronal functioning can be proven by the results of behavioral tests, which were also noted by a number of foreign authors [77].

requires the necessity of searching the new approaches to the problem of age-related hearing

Characteristics of Hearing in Elderly People http://dx.doi.org/10.5772/intechopen.75435 77

Presbycusis does not develop in all people. Genetic mechanisms are considered to be the crucial cause of age-related hearing loss development. Different diseases acquired throughout the lifetime and other factors can contribute to hearing loss progression in the case of heredi-

Assessment of pathology level in the auditory system in patients with presbycusis is essential during the choice of further treatment and hearing rehabilitation. Therefore, it is necessary to use various audiologic methods during elderly people examination, including tests to evaluate the central auditory pathways. Elderly patients often suffer from impaired speech intelligibility, especially in background noise. This is one of the central auditory processing disorder symptoms. Currently, there are no data about significant achievements in development of drugs, improving speech intelligibility. According to research on brain neuroplasticity, specially designed auditory training programs have been shown to be able to refine speech signals' processing in central auditory pathways even in aged people. Auditory training designed with consideration of the individual features of auditory deficit should be included into rehabilitation programs of aged people with speech intelligibility disorders.

impairment.

tary predisposition to presbycusis.

**Conflict of interest**

**Author details**

**References**

p. 300 [In Russian]

There are no conflicts of interests.

Maria Boboshko\*, Ekaterina Zhilinskaya and Natalia Maltseva

Laboratory of Hearing and Speech of Academician I.P. Pavlov First St. Petersburg State

[1] Glorig A, Davis H. Age, noise and hearing loss. The Annals of Otology, Rhinology, and

[2] Hinchliffe R. The anatomical locus of presbyacusis. The Journal of Speech and Hearing

[3] Lopotko A, Plouzhnikov M, Atamouradov M. Presbyacusis. Ashkhabad: Ylym; 1986.

Laryngology. 1961;**70**:556-571. DOI: 10.1177/000348946107000219

Disorders. 1962;**27**(4):301-310. DOI: 10.1044/jshd.2704.301

\*Address all correspondence to: boboshkom@gmail.com

Medical University, St. Petersburg, Russia

Neuronal changes depend on the activity of training and amount of stimulation, and the sooner the stimulation begins after the detection of impaired intelligibility, the best results can be expected, however, to start training is never too late [65].

One of the basic principles of the auditory training must be concordance between the used material and age and linguistic skills of a patient. If the materials and tasks exceed the cognitive and linguistic skills of a patient, he/she will have no interest in the training, and there will be no progress. In contrast, material for adult training should not be childish and too simplistic. Motivation is also one of decisive factors in the training success. To increase the motivation, patients should understand the principles and the theory of action of the auditory training.

The use of a various tasks, the variation of a stimulus in the auditory training helps to maintain a patient's attention, increases motivation and makes the training more efficient. The complexity of tasks during the training can vary automatically: as soon as a patient reaches the predetermined level, the task becomes more difficult. Careful monitoring of a patient's progress is important. For each patient, an individual profile of functional deficit, which reflects the processing of information in the central auditory pathways, cognitive and language skills, should be developed, and an emphasis on training deficit skills should be done while planning the rehabilitation.
