**5. Frequency following response: evaluation in adults and the elderly**

In the adult and elderly population, the need for detailed audiological investigation increases when the patient complains of hearing difficulties, even if auditory thresholds appear normal.

The evaluation of the FFR first involves time and prosody recordings, which provide important information about consonant and vowel discrimination and also aid in the perception of intonation [48]. For adults, but especially in the elderly, participation in these sorts of tests can assist in rehabilitation, either using a hearing aid or auditory training (or both).

The clinical usefulness of the FFR in gauging how well auditory information is being processed is unquestionable. In adults and the elderly, many studies have already been done to identify how the FFR can help in diagnosing complaints related to central auditory processing, thereby allowing better rehabilitation.

The latencies (mean and standard deviation) for adults and the elderly are presented in **Table 11**. The values come from Skoe et al. [19] who used Biologic and


∑*: average, Med: median, SD: standard deviation, R: right, L: left. Sample: 40 children and adolescents (8–16 years old).*

#### **Table 11.**

*Complex VA (slope and area) values for age range using syllable/da/of 40-ms duration performed in children with normal hearing (silent conditions) [30].*


#### **Table 12.**

*FFR latency values based on mean values in Table 11 plus two standard deviations.*

Navigator Pro equipment. In this study, subjects aged between 18 and 72 years and distributed in 6 age brackets were used. In the case of adults, the authors list values for subjects aged 21–30 years (*n* = 143) and found that latency values tended to increase with age. Thus, the researchers emphasized the importance of conducting research on FFRs in different age groups, since normative values can be modified with the aging process.

In **Table 12** the maximum values of each wave are listed by adding two standard deviations to those in **Table 13**. Assuming the distribution is Gaussian means that this measure will cover 95% of the population.

Undoubtedly, the largest number of FFR studies have been performed using the Navigator Pro model from Biologic. Researchers tend to use this equipment together with the Intelligent Hearing Systems and SmartEP software [7, 49, 50].

One study aimed to assess the processing of auditory information in those with hearing loss through an evaluation of eight individuals, aged 46–58 years, with hearing loss [7]. FFRs (collected by SmartEP) were correlated with results from two auditory processing behavioral tests—the masking level difference test and the random gap detection test. No correlation was found between FFR and these tests. The researchers found that the generation of this potential is extremely complex and could encompass several functions and does not depend on just temporal resolution

**147**

**Age**

**Number** **V**

117–21 221–30 330–40 440–50 550–60 660–73 **Table 13.**

24

6.92

7.89 ∑*: Average (ms), SD: standard deviation, %: percent detectability for each peak.*

23.05

31.37

39.68 *FFR latency values for syllable /da/ of 40-ms duration, (silence) performed in adults and the elderly with normal hearing [19].*

48.84

0.38

91.67

0.46

91.67

0.61

83.33

0.55

83.33

0.46

83.33

0.59

100

26

6.86

7.89

23.08

31.57

39.92

48.72

0.32

92.31

0.44

92.31

0.71

76.92

0.70

96.15

0.77

92.31

1.00

88.46

11

6.67

7.64

22.84

31.26

39.49

48.30

0.19

100

0.29

100

0.71

90.90

0.30

100

0.22

100

0.65

90.90

32

6.61

7.53

22.52

31.09

39.54

48.21

0.33

100

0.43

100

0.56

96.88

0.50

96.88

0.42

96.88

0.46

93.75

143

6.65

7.60

22.60

31.12

39.61

48.33

0.26

100

0.34

100

0.67

95.8

0.71

100

0.62

99.30

0.73

97.90

54

6.58

7.53

22.41

31.02

39.50

48.26

0.23

100

0.31

96.30

0.40

92.6

0.44

94.44

0.46

98.15

0.34

98.15

**A**

**D**

**E**

**F**

**O**

**V** 

**%**

**A** 

**%**

**D** 

**%**

**E (SD)**

**%**

**F (SD)**

**%**

**O** 

**%**

**(SD)**

**(SD)**

**(SD)**

**(SD)**

**Latency** 

**∑ (mean in milliseconds)**

**Standard deviation**

*The Frequency Following Response: Evaluations in Different Age Groups*

*DOI: http://dx.doi.org/10.5772/intechopen.85076*


**Table 13.** *FFR latency values for syllable /da/ of 40-ms duration, (silence) performed in adults and the elderly with normal hearing [19].*

#### *The Frequency Following Response: Evaluations in Different Age Groups DOI: http://dx.doi.org/10.5772/intechopen.85076*

*The Human Auditory System - Basic Features and Updates on Audiological Diagnosis and Therapy*

∑ 8–11 0.38 0.31

Med 8–11 0.37 0.31

SD 8–11 0.12 0.11

∑*: average, Med: median, SD: standard deviation, R: right, L: left.*

*Sample: 40 children and adolescents (8–16 years old).*

*with normal hearing (silent conditions) [30].*

**Table 11.**

*Data from [19]. SD: standard deviation.*

**Table 12.**

**Complex VA**

12–16 0.33 0.34

12–16 0.28 0.31

12–16 0.16 0.16

*Complex VA (slope and area) values for age range using syllable/da/of 40-ms duration performed in children* 

17–21 54 7.04 8.15 23.21 31.9 39.50 48.94 21–30 143 7.17 8.28 23.4 32.54 40.84 49.79 30–40 32 7.27 8.39 23.64 32.09 40.38 49.13 40–50 11 7.05 8.22 24.26 31.86 39.93 49.6 50–60 26 7.5 8.77 24.5 32.97 41.46 50.72 60–73 24 7.68 8.81 24.27 32.47 40.60 50.02

**V A D E F O**

**Age (years) Number Latencies (maximum in milliseconds + 2 SD)**

**Age range Slope VA (ms/μV) Area VA (ms × μV)**

Navigator Pro equipment. In this study, subjects aged between 18 and 72 years and distributed in 6 age brackets were used. In the case of adults, the authors list values for subjects aged 21–30 years (*n* = 143) and found that latency values tended to increase with age. Thus, the researchers emphasized the importance of conducting research on FFRs in different age groups, since normative values can be modified

*FFR latency values based on mean values in Table 11 plus two standard deviations.*

In **Table 12** the maximum values of each wave are listed by adding two standard deviations to those in **Table 13**. Assuming the distribution is Gaussian means that

Undoubtedly, the largest number of FFR studies have been performed using the Navigator Pro model from Biologic. Researchers tend to use this equipment together

One study aimed to assess the processing of auditory information in those with hearing loss through an evaluation of eight individuals, aged 46–58 years, with hearing loss [7]. FFRs (collected by SmartEP) were correlated with results from two auditory processing behavioral tests—the masking level difference test and the random gap detection test. No correlation was found between FFR and these tests. The researchers found that the generation of this potential is extremely complex and could encompass several functions and does not depend on just temporal resolution

with the Intelligent Hearing Systems and SmartEP software [7, 49, 50].

**146**

with the aging process.

this measure will cover 95% of the population.

or selective attention [7]. Also seeking to correlate FFRs with hearing loss, Peixe et al. [49] evaluated 11 individuals, aged 23–59 years, with moderately severe hearing loss. They concluded that hearing loss may cause an increase in the FFR wave latency, but the waves are still present so long as the stimulus intensity is adjusted. In other words, the presence of FFR waves is related to the audibility of the signal.

Another interesting study was conducted with 30 young Indian adults aged 18–25 years [50]. The evaluation was carried out with the SmartEP equipment, and FFRs were present in all subjects evaluated. The latency and amplitude values of the analyzed elements were: wave V (lat = 6.81 ms and amp = 0.19 μV), wave C (lat = 16.82 ms and amp = 0.24 μV), wave D (lat = 24.75 ms and amp = 0.32 μV), wave E (lat = 31.36 ms and amp = 0.37 μV), and wave F (lat = 40.04 ms and amp = 0.29 μV).

Worldwide, there is a large increase in the number of elderly people. This entails providing better care for the elderly in all aspects of their health. With aging, there are structural changes in the peripheral and central auditory system which can lead to a decline in hearing. This, in turn, causes complaints of difficulty in understanding speech, especially in unfavorable environments [51, 52]. These impairments have a great impact on the life of the elderly, since in addition to causing social isolation, it can also lead to a depression and reduce cognitive function [53].

Only a few studies have focused on FFR in the elderly, with the most reported population being young adults [54]. Some researchers have pointed to the clinical applicability of FFR in different populations and with different pathologies [7, 19, 37, 55].

The effects of presbycusis on FFRs have been investigated in 18 individuals aged 61–78 years with hearing loss at frequencies of 2, 4, and 8 kHz (and compared with the responses of a control group of 19 young adults aged 20–26 years with normal hearing) [37]. The elderly group had lower amplitudes and increased latencies compared to the control group, demonstrating that the FFR can be affected by aging as well as hearing loss, but in different ways.

The effects of hearing loss on FFRs were described in a sample of 30 elderly individuals aged 60–71 years who were divided into two groups matched by gender and intelligence quotient: (i) normal hearing, and (ii) mild to moderate hearing loss [35]. With ABR clicks, all subjects had normal responses. FFR testing indicated that individuals with hearing loss could be assessed with this procedure, but there were changes in the frequency responses. In the elderly with hearing loss, there was a breakdown in the perception of the speech signal, which resulted in differences in signal parameters compared to the group with normal thresholds. This breakdown in neural synchrony may explain the greater difficulty subjects with hearing loss have in speech perception.

The evaluation of FFR in noisy environments is becoming more widespread, Thus, one study was carried out with 111 individuals between 45 and 78 years of age (mean 61.1 years) with normal to moderate hearing loss [56]. All subjects presented values within normal limits for the Montreal Cognitive Assessment (MoCA) and click ABR. In addition, they were tested on the SSQ (Speech, Spatial, and Qualities of Hearing Scale) which relates to auditory quality, as well as to the Quick Speech-in-Noise test (QuickSIN), in which phrases are presented binaurally with a verbal background babble. The FFR assessment demonstrated an increase in O-wave latency associated with speech comprehension difficulty in competing noise environments.

Supporting the observation that FFR traces are affected by increasing age, research on 34 individuals aged 22–77 years with normal hearing [57] found a decrease of the amplitude was associated with an increase in latency (**Figures 1** and **2**).

**149**

appear to be absent.

**Figure 2.**

**Figure 1.**

parameters are shown in **Table 14**.

*The Frequency Following Response: Evaluations in Different Age Groups*

*FFRs of an infant 13 days old. Authors' data with FFR performed using SmartEP.*

**Figure 3** shows an FFR done on an adult aged 25 and on one aged 70. The shape of the FFR is similar in both, but there is an increase in latencies and some waves

*FFRs of two 9-year-old-children. The top trace represents a normal response and the second represents an* 

In these FFR tracings, it can be seen that the elderly subject had an increase in latency of all waves compared to the younger adult. Aging causes a progressive loss of structure or functioning of neurons, which can be seen as decreased auditory evoked potentials. Through the FFR, it is seen that there is also a reduction in the

Our FFR evaluation in adults and the elderly used IHS equipment and the

speed of neural activation from brainstem to cortical structures.

*abnormal response. Authors' data using BioMARK software and Biologic equipment.*

*DOI: http://dx.doi.org/10.5772/intechopen.85076*

*The Frequency Following Response: Evaluations in Different Age Groups DOI: http://dx.doi.org/10.5772/intechopen.85076*

**Figure 1.** *FFRs of an infant 13 days old. Authors' data with FFR performed using SmartEP.*

#### **Figure 2.**

*The Human Auditory System - Basic Features and Updates on Audiological Diagnosis and Therapy*

or selective attention [7]. Also seeking to correlate FFRs with hearing loss, Peixe et al. [49] evaluated 11 individuals, aged 23–59 years, with moderately severe hearing loss. They concluded that hearing loss may cause an increase in the FFR wave latency, but the waves are still present so long as the stimulus intensity is adjusted. In other words, the presence of FFR waves is related to the audibility of the signal. Another interesting study was conducted with 30 young Indian adults aged 18–25 years [50]. The evaluation was carried out with the SmartEP equipment, and FFRs were present in all subjects evaluated. The latency and amplitude values of the analyzed elements were: wave V (lat = 6.81 ms and amp = 0.19 μV), wave C (lat = 16.82 ms and amp = 0.24 μV), wave D (lat = 24.75 ms and amp = 0.32 μV), wave E (lat = 31.36 ms and amp = 0.37 μV), and wave F (lat = 40.04 ms and

Worldwide, there is a large increase in the number of elderly people. This entails providing better care for the elderly in all aspects of their health. With aging, there are structural changes in the peripheral and central auditory system which can lead to a decline in hearing. This, in turn, causes complaints of difficulty in understanding speech, especially in unfavorable environments [51, 52]. These impairments have a great impact on the life of the elderly, since in addition to causing social isolation, it can also lead to a depression and reduce cognitive function [53]. Only a few studies have focused on FFR in the elderly, with the most reported population being young adults [54]. Some researchers have pointed to the clinical applicability of FFR in different populations and with different

The effects of presbycusis on FFRs have been investigated in 18 individuals aged 61–78 years with hearing loss at frequencies of 2, 4, and 8 kHz (and compared with the responses of a control group of 19 young adults aged 20–26 years with normal hearing) [37]. The elderly group had lower amplitudes and increased latencies compared to the control group, demonstrating that the FFR can be affected by aging as

The effects of hearing loss on FFRs were described in a sample of 30 elderly individuals aged 60–71 years who were divided into two groups matched by gender and intelligence quotient: (i) normal hearing, and (ii) mild to moderate hearing loss [35]. With ABR clicks, all subjects had normal responses. FFR testing indicated that individuals with hearing loss could be assessed with this procedure, but there were changes in the frequency responses. In the elderly with hearing loss, there was a breakdown in the perception of the speech signal, which resulted in differences in signal parameters compared to the group with normal thresholds. This breakdown in neural synchrony may explain the greater difficulty subjects with hearing loss

The evaluation of FFR in noisy environments is becoming more widespread, Thus, one study was carried out with 111 individuals between 45 and 78 years of age (mean 61.1 years) with normal to moderate hearing loss [56]. All subjects presented values within normal limits for the Montreal Cognitive Assessment (MoCA) and click ABR. In addition, they were tested on the SSQ (Speech, Spatial, and Qualities of Hearing Scale) which relates to auditory quality, as well as to the Quick Speech-in-Noise test (QuickSIN), in which phrases are presented binaurally with a verbal background babble. The FFR assessment demonstrated an increase in O-wave latency associated with speech comprehension difficulty in competing

Supporting the observation that FFR traces are affected by increasing age, research on 34 individuals aged 22–77 years with normal hearing [57] found a decrease of the

amplitude was associated with an increase in latency (**Figures 1** and **2**).

**148**

amp = 0.29 μV).

pathologies [7, 19, 37, 55].

have in speech perception.

noise environments.

well as hearing loss, but in different ways.

*FFRs of two 9-year-old-children. The top trace represents a normal response and the second represents an abnormal response. Authors' data using BioMARK software and Biologic equipment.*

**Figure 3** shows an FFR done on an adult aged 25 and on one aged 70. The shape of the FFR is similar in both, but there is an increase in latencies and some waves appear to be absent.

In these FFR tracings, it can be seen that the elderly subject had an increase in latency of all waves compared to the younger adult. Aging causes a progressive loss of structure or functioning of neurons, which can be seen as decreased auditory evoked potentials. Through the FFR, it is seen that there is also a reduction in the speed of neural activation from brainstem to cortical structures.

Our FFR evaluation in adults and the elderly used IHS equipment and the parameters are shown in **Table 14**.

#### **Figure 3.**

*FFRs of an adult aged 25 years (top) and another aged 70 (bottom). Note the increase in latency of the waves. Authors' data using SmartEP equipment.*


**151**

*The Frequency Following Response: Evaluations in Different Age Groups*

FFR evaluations can be included as an extra examination in diagnostic testing and have an important role in crosschecking the results. It can also greatly assist making differential diagnoses in different clinical populations. However, each age group has FFRs with specific characteristics, so it is important that the audiologist has access to good normative values for the different age groups (infants and toddlers, young children, children and adolescents, adults and the

10–20 International System a standard system for electrode location

AEP auditory evoked potential. Evoked potential when using an auditory stimulus BioMARK Biological Marker of Auditory Processing is software

synthetic syllable (usually /da/)

CV syllable a phoneme produced by a consonant and a vowel

Onset portion the first part of an FFR that reflects the consonant SAB Scale of Auditory Behavior, a questionnaire for monitoring auditory processing skills Sustained portion the second part of an FFR that reflects the vowel

that compares responses from a click to those from a

ABR auditory brainstem response

CANS central auditory nervous system CAP central auditory processing

FFR frequency following response

CNS central nervous system

Artificial human speech produced by a computer

CAPD central auditory processing disorder

Synthesized speech

*DOI: http://dx.doi.org/10.5772/intechopen.85076*

**6. Conclusion**

elderly).

**Terminology**
