Advanced Arab Academy of Audio-Vestibulogy Journal

: 2015  |  Volume : 2  |  Issue : 2  |  Page : 59--63

Sensitivity of CHIRP auditory brainstem response and auditory steady state response for detecting normal hearing in children

Haider W Alsarhan 
 College of Medicine, Al-Mustansiriya University, Baghdad, Iraq

Correspondence Address:
Haider W Alsarhan
College of Medicine, Al-Mustansiriya University, Baghdad


Background In recent years, great development of electrophysiological procedures for detection of hearing level in infants and children has been achieved - click auditory brainstem response (ABR), tone burst ABR, and notched noise ABR. The two most recent methods are CHIRP signal ABR and auditory steady state response (ASSR). Aim of the study The aim of this study was to identify the best electrophysiological method for detecting normal hearing thresholds. Patients and methods A prospective study was conducted on 80 ears from 58 children aged from 1 to 2 years that showed normal hearing thresholds in all frequencies in visual reinforcement audiometry (VRA) cooperatively, for which CHIRP ABR and ASSR were evaluated and the results were analyzed. Results Both CHIRP ABR and ASSR showed moderate correlation with VRA at 0.5 and 1 kHz and a strong correlation at 2 and 4 kHz. CHIRP ABR thresholds were closer to VRA thresholds and showed a sensitivity of 100%, detecting normal hearing thresholds at all frequencies, whereas the sensitivity of ASSR in detecting normal hearing was decreased with decreasing testing frequency, reaching a low percentage of 57.5% at 0.5 kHz. Conclusion CHIRP ABR is the best electrophysiological method for assessing hearing thresholds in children whose hearing average is expected to be close to normal threshold.

How to cite this article:
Alsarhan HW. Sensitivity of CHIRP auditory brainstem response and auditory steady state response for detecting normal hearing in children.Adv Arab Acad Audio-Vestibul J 2015;2:59-63

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Alsarhan HW. Sensitivity of CHIRP auditory brainstem response and auditory steady state response for detecting normal hearing in children. Adv Arab Acad Audio-Vestibul J [serial online] 2015 [cited 2019 Jan 23 ];2:59-63
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The importance of hearing integrity within the first 2-4 years after birth for normal acquisition of speech and language has long been appreciated [1] . During this sensitive period, speech and language will almost always develop rapidly and normally if the auditory and language regions of the brain are adequately stimulated by sound, especially the sounds of communication [2] .

There are many methods of testing hearing levels in the pediatric age group, including distraction test, the auropalpebral (blink) reflex, visual reinforcement audiometry (VRA), conditioned orientation audiometry, play audiometry, and classical pure-tone audiometry for older children [2] .

More recently developed methods such as auditory-evoked responses are electrophysiological recordings of responses to sounds. With proper test protocols, the responses can be recorded clinically from activation of all levels of the auditory system, from the cochlea to the cortex [3] . Among these responses, the auditory brainstem response (ABR) (often referred as the brainstem auditory evoked response, or BAER) is applied most often clinically [2] . There are more recent modifications of standard ABR to click stimulus, which are tone burst, tone burst with high frequency ipsilateral masking ABR, and tone burst with notched noise masking ABR [4] . More recently, CHIRP ABR has been used; it provides a better synchronization of the neural response due to the compensation of the travelling wave delay in the basilar membrane [5] .

The auditory steady state responses (ASSR) test is an electrophysiological test that evaluates, among other aspects, neural synchrony, on the basis of the frequency or amplitude modulation of tones [6] and is very useful for the estimation of auditory thresholds in infants and young children [3],[7] .

 Aim of the study

The aim of this study was to determine the sensitivity of detecting normal hearing of the two most recent types of frequency-specific electrophysiological hearing threshold detection methods, which are CHIRP signal ABR and ASSR.

 Patients and methods

Fifty eight patients with an age range one to two years (38 male and 20 female) referred for hearing assessment to our private hearing center (which is the place of the study) in Baghdad, Iraq, from 1 September 2013 to 25 October 2014 were included in the study.

Short history taking from the parents about the hearing state of the child, or any family history of hearing loss, was carried out. General ENT examination and otoscopic examination of the ears for acute otitis media or other upper airway infection were performed. In case of acute infection, the hearing evaluation delayed until after resolution of the acute infective state (by prescribing a proper treatment). If wax was found, it was removed from the ear before hearing evaluation.

Hearing evaluation was carried out using computer-assisted VRA (four frequencies VRA) before sedating the child by administering chloralhydrate syrup at a dose of 20 mg/kg body weight. After the child was totally asleep, middle ear impedance, acoustic reflex at 1 kHz, screening for distortion products otoacoustic emissions (DPOAE), screening for transient evoked otoacoustic emissions (TEOAE), four frequencies CHIRP signal ABR (CHIRP ABR), and four frequencies ASSR evaluation were performed. The four frequencies measured with VRA, CHIRP ABR, and ASSR were 0.5, 1, 2, and 4 kHz.

VRA was performed using Piano plus VRA audiometer, and tympanometry (impedance curve and acoustic reflex at 1 kHz) was performed using Otowave 102-1 (Inventis, Italy). Screening for DPOAE and TEOAE were performed using a neuro-audio-screen unit, and CHIRP ABR and ASSR evaluations were performed using corona unit. The frequency of the tympanometer probe was 226 Hz, and the frequency modulation in ASSR was 80 Hz.

A total of 58 children were selected to be included in the study. All children referred to the specialized hearing center during the period of the study were included in the study, except the children who were excluded on the basis of the following exclusion criteria.

Exclusion criteria

Age less than 1 year.Age more than 2 years.Past history suggesting hearing loss.Family history of hearing loss.History or finding suggesting mental retardation.Abnormal impedance curve.Failure of obtaining positive acoustic reflex at 1 kHz up to 85 dB.Screening test showed REFER.REFER screening test of TEOAE.Abnormal hearing threshold at any frequency, obtained using VRA.Incorporation of the child with VRA.Failure to complete the full battery of tests required for the study of at least one ear (the effect of sedation was not sufficient for the child to remain asleep for sufficient time to complete full tests for at least one ear).When the child was fully sedated, CHIRP ABR and ASSR evaluation was performed to the right ear first and then to the left ear. If the child continued sleeping until the completion of tests for both ears then the results of both ears were included. If the child woke up after completion of the tests of only one ear then the results of only that ear were included in the study.


In 22 children, the results of both the right and the left ear were included in the study design, whereas in the other 36 children the results of only one ear were included in the study, as the sedation time was not enough to maintain the children asleep and the children were awaked during the tests of the second ear and were excluded from the study.

[Figure 1] [Figure 2] [Figure 3] [Figure 4] show the results of VRA, CHIRP ABR, and ASSR thresholds of the 80 ears that were included in the study.{Figure 1}{Figure 2}{Figure 3}{Figure 4}

[Table 1] shows the correlation regression (R) value for the 80 ears included in the study in all frequency range included in the study. There was a moderate strength correlation of CHIRP ABR with VRA and of ASSR with VRA at 0.5 and 1 kHz, whereas the correlation was strong at 2 and 4 kHz.{Table 1}

All CHIRP ABR thresholds recorded in this study in all frequencies were normal (≤25 dB), whereas ASSR thresholds recorded were normal only at 2 and 4 kHz. A total of 34 of 80 ears (42.5%) were abnormal (more than 25 dB) at 0.5 kHz and seven of 80 ears (8.75%) were abnormal at 1 kHz [Figure 5]. The mean threshold of ASSR at 0.5 kHz was abnormal (27.31 dB), whereas the mean threshold of ASSR in other frequencies and the mean threshold of CHIRP ABR in all frequencies measured in the study were within the normal range (≤25 dB) [Table 2].{Figure 5}{Table 2}

[Table 3] shows the sensitivity of detecting normal hearing threshold of CHIRP ABR and ASSR in the frequencies included in the study and it shows that the sensitivity was 100% at all frequencies in CHIRP ABR and in 4 and 2 kHz in ASSR, but the sensitivity of ASSR decreased to 91.25% at 1 kHz and to 57.50% at 0.5 kHz.{Table 3}


Sampling of the study

All children with a history of hearing loss or family history of hearing loss were excluded because the study was designed to include children with normal hearing. Only children between 1 and 2 years of age were included in the study, because older children quickly restrict responses and become less motivated by the visual reward [2] . Children with any possibility of conductive hearing loss on evaluation with tympanometry [8],[9] - that is, with abnormal impedance curve - were excluded. All cases that failed to get acoustic reflex positive at 80 or 85 dB were excluded from the study as the acoustic reflex threshold systematically increased directly with increased sensory hearing loss. As a rule of thumb, acoustic reflex threshold signals of less than 85 dB HL were generally associated with normal hearing sensitivity, whereas acoustic reflex thresholds greater than 90 dB HL almost always reflected a communicatively important sensory hearing loss (>30 dB HL) [10] . All children who were referred for screening test of TEOAE were excluded from the study because OAEs are not normally present when the hearing loss is greater than about 30 dB HL [11] . Similarly, all children who were referred for screening test of DPOAE were excluded from the study. Lyons et al. [12] reported a 98% sensitivity with the result of screening audiometry using a combination of DPOAE and tympanometry. Children with abnormal hearing threshold at any frequency obtained with VRA, children with incorporation with VRA, or children with a history or finding suggesting mental retardation were excluded from the study to comply with the study design that depends on VRA as the psychological threshold (constant factor) by which all other electrophysiological thresholds are compared with.

Analysis of the results of the study

The results showed a strong correlation of the thresholds obtained using both the electrophysiological tests (CHIRP signal ABR and ASSR) with the psychological thresholds obtained with VRA at 2 and 4 kHz. However, there was a moderate correlation obtained at 0.5 and 1 kHz. These results are comparable to the results of Chen et al. [13] , who studied the relation of ASSR and ABR with pure-tone thresholds in adults with normal hearing and showed that there was a good correlation of ASSR and ABR thresholds with pure-tone thresholds. Moreover, our results are comparable to the results of Wu et al. [14] , who studied the relation of ASSR, click ABR, and tone burst ABR with behavioral pure-tone thresholds in individuals with normal hearing and showed that both ASSR, click ABR and tone burst ABR thresholds had high correlations with pure-tone thresholds.

All CHIRP ABR thresholds at all frequencies were normal or nearer to behavioral thresholds than to ASSR thresholds, and the sensitivity of detecting normal hearing records was 100% in all frequencies. These findings are similar to the findings of Xu [15] , who showed in their study that CHIRP ABR thresholds are very close to behavioral hearing levels.

ASSR thresholds at lower frequency range showed abnormal records in various percentages and the mean ASSR record at 0.5 kHz of 80 ears included in this study was higher than the normal limit. The sensitivity of this test to detect normal thresholds was reduced with a decrease in the tested frequency to as low as 57.50% at 0.5 kHz. These findings give an impression that ASSR is a poor method for the estimation of hearing thresholds, especially at low-frequency and mid-frequency range (which are the important frequencies of speech). Xu [15] also showed in their study that the use of a CHIRP ABR testing ensures higher sensitivity and accuracy than that of ASSR for measuring frequency-specific thresholds in young children. Moreover, our results of ASSR thresholds obtained in this study are comparable to the results of Van Maanen and Stapells [16] , who studied ASSR records in 54 children with normal hearing and showed that most (> or = 90%) of the infants showed present ASSRs at 49, 45, 36, and 32 dB HL at 500, 1000, 2000, and 4000 Hz, respectively [16] . Moreover, our results of this study are highly comparable to the results of the study of Wu et al. [14] , who showed that ABR thresholds were recorded much closer to behavioral threshold than to ASSR thresholds [14] .

Newer studies imply the use of CHIRP signal stimuli in ASSR study (what is called CHIRPs ASSR). Venail et al. [17] showed that narrow-band CE-CHIRPS ASSR allow a fast and reliable assessment of auditory thresholds in children, especially in the low-frequency range [17] , by comparison with other stimuli. This newly designed test method will be very useful in future for solving problems of sensitivity of this test in low and mid frequencies (speech frequencies) when it will be released for clinical use.


CHIRP ABR is the best electrophysiological method for detecting hearing thresholds in children in whom the hearing average is expected to be close to normal threshold.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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