**4. Criteria of normality**

Before presenting the criteria of normality, it is important to understand the influence of the maturational process and gender in response to speech ABR.

#### **4.1. Maturation**

The response of ABR with nonverbal stimulus is mature around 18 months, while the speech ABR appears to be mature by the age of 5 [10]. This way a procedure can be used in young and school-age children, helping in the differential diagnosis of diseases with similar symptoms [14]. Further studies are being conducted to regulate the normal values for different age range and confirm the age of maturation of central auditory system for verbal sounds.

According to Yamamuro et al. [39], age affects the coding of sounds by a single stimulus or the complex and neural timing and auditory skills are improved over the years. The responses of speech ABR in a child of 5 years are not so different from a child's responses in the age group of 8–12 years , whereas a child's responses in the age group of 3–4 years are very different in morphological aspect as related to the latency time.


Note: Parametric study in normal adults.

**Table 1.** Parametric study (mean and standard deviation) by syllable /da/, 40 ms, (silence) performed in adults with normal hearing (Song et al. [16]) on the right ear in two different conditions (test and retest).

#### **4.2. Gender influence**

sound intensity or with subtitle [16, 23, 40, 41, 50], which seems that it keeps them quiet and relaxed during the assessment. Other researchers allow the patient to choose between watching

Different parameters are being used. The parameters most cited in the literature about the assessment of speech ABR and with good clinical results are presented below in **Chart 1** (Speech ABR parameters). Note that there is a well-written tutorial by Skoe and Kraus [4] with detailed, clear, and objective information about the functioning and clinical application of speech ABR. This tutorial can be a material support to those interested in unraveling this new

Before presenting the criteria of normality, it is important to understand the influence of the

The response of ABR with nonverbal stimulus is mature around 18 months, while the speech ABR appears to be mature by the age of 5 [10]. This way a procedure can be used in young and school-age children, helping in the differential diagnosis of diseases with similar symptoms

a movie or sleep during the assessment process [24, 45].

16 Advances in Clinical Audiology

and effective electrophysiological assessment method.

**Parameters Setting**

Software BioMARK Electrode montage Cz, M1, and M2 Stimulated ear Right ear Stimulus Speech Stimulus type Syllable /da/ Stimulus duration 40 ms Stimulus polarity Alternating Stimulus intensity 80 dB SPL Stimulus rate 10.9/sec Number of sweeps 6000

Equipment Biologic navigator pro

Replicability Twice for 3000 sweeps

Transducer Insert

**Chart 1.** Speech ABR parameters.

**4. Criteria of normality**

**4.1. Maturation**

Assessment condition Watch a movie

maturational process and gender in response to speech ABR.

Previous studies of literature have shown that there are differences of responses in the auditory perception between genders with better performance in female in the entire trajectory of the peripheral auditory and central nervous system [53, 54]; however, when the focus of analysis is the speech ABR, it was observed that women have better responses (higher values for amplitudes and lower values for latencies), and it was only the initial portion of the speech stimuli of the coding process when compared to men [55]. Differences in speech ABR responses between genders were explained by the premise that the synapses of the afferent and efferent systems of the auditory system are strongly influenced by the hormone estrogen activity [56].

#### **4.3. Normative data**

There are some studies that are used as parametric models for the analysis of speech ABR. Normative data for young adults (19–36 years old) with normal hearing and analysis of all the waves are presented in **Table 1** (parametric study [mean and standard deviation] by syllable / da/, 40 ms, [silence] performed in adults with normal hearing—Song et al. [16]—on the right

ear in two different conditions—test and retest [16]). Two studies for children and adolescents will be presented: (i) composed of children between 8 and 12 years of age with normal hearing and with the analysis of waves V, A, C, and F and VA complex in **Table 2** (parametric study [mean and standard deviation] by syllable /da/, 40 ms, [silence] performed in children with normal hearing—Russo et al. [15]—on the right ear [15]) and (ii) composed of children and adolescents between 8 and 16 years of age with normal hearing and examination of all the waves in **Table 3** (parametric study [mean and standard deviation] by syllable /da/, 40 ms [silence] performed in children and adolescent with normal hearing—Sanfins et al. [22]—on the right and left ears [22]).


Russo et al. [15] studied 36 and 38 children and adolescent (17 females) with normal hearing (8–12 years old).

Note: Parametric study in normal children.

**Table 2.** Parametric study (mean and standard deviation) by syllable /da/, 40 ms (silence) performed in children with normal hearing (Russo et al. [15]) on the right ear.

The majority of studies about speech ABR assessment was performed with monoaural stimulus on the right ear [13, 24, 29, 39, 49, 50]. The choice for the assessment only on the right ear is related to the advantage of the left hemisphere for processing of language sounds. Associated with this fact, earlier research has shown that there are no statistically significant differences between the responses on the right and left ears in subjects with normal hearing and typical development. However, there are many conditions to be studied through the speech ABR, and it is important to consider whether there are differences in responses between the ears.

Thereby, the responses on the right and left ears were presented in the population of children and adolescents with normal hearing and normal development so that it can be used as a comparison with the responses obtained in subjects with different pathologies.

It is noted that the parametric studies provide a direction to the researchers. It is fundamental to know the parameters of collection and analysis of each reference author before the use of


this data. Each research center or clinic should carry out its own normative study for the different age groups.

Sanfins et al. [22] studied 40 children and adolescent (25 females) with normal hearing (8–16 years old; 10.95 ± 2.0).

Note: Parametric study in normal children and adolescent.

**Table 3.** Parametric study (mean and standard deviation) by syllable /da/, 40 ms (silence) performed in children and adolescent with normal hearing (Sanfins et al. [22]) on the right and left ears.
