Narrow-band chirp and tone burst auditory brainstem response as an early indicator of synaptopathy in industrial workers exposed to occupational noise

Abstract

This study aims at characterizing and comparing the findings of auditory brainstem response (ABR) using narrow-band chirp (NB-chirp) and tone burst (TB) for both latency and amplitude parameters among those exposed to occupational noise and to determine which among the two serves as a better indicator of noise-induced cochlear neuropathy. Forty adult males in the age range of 20-35 years were considered, wherein 20 of them were exposed to noise > 80 dB (A) for 8 hours per day constituting Noise-exposed group; and Control group consisted of 20 individuals without occupational noise exposure. ABR was recorded using NB-chirp and TB for four frequencies at 80 dB nHL through Etymotic Research-3A (ER-3A) Insert phones using Interacoustics Eclipse EP-25 in individuals with and without noise exposure. MANOVA was performed to compare between TB ABR and NB-chirp ABR between the two groups. Statistical analysis revealed a notable difference for NB-chirp comparisons between the two groups at three frequencies: 500 Hz, F(1, 38) = 10.6; 1000 Hz, F(1, 38) = 7.91; and 2000 Hz, F(1, 38) = 6.64. Whereas, the difference was evident at only 500 Hz: F(1, 38) = 4.98 in case of TB ABR. However, there was no significant difference seen at any of the frequencies for amplitude parameters in both TB and NB-chirp ABR. Latency of wave V using NB-chirp was considered to be a better indicator compared to TB, acting as a better clinical tool in early identification, diagnosis, and monitoring of noise induced hearing loss (NIHL).

Advantages of Narrow Band CE-Chirp ABR Compared to Tone Burst ABR in Adults with Normal Hearing

“…In our study, only at 4 kHz 60 dB nHL level, NB CE-Chirp ABR wave amplitudes were found to be greater than TB ABR wave amplitudes (p=0.038). Similar to our research results, Megha et al (25) found no significant difference in any of the frequencies for amplitude parameter in TB and NB CE Chirp ABR. At high levels of chirp stimulus, desynchronization develops as a result of overstimulation on the cochlear basilar membrane.…”

“…The low frequencies in the NB CE-Chirp are being presented early than high frequency octave bands. Thus NB-CE Chirp provides maximum stimulation into the cochlea (12,25). Ferm et al (16) reported that the NB CE-Chirp ABR thresholds were found to be lower than the tone pip thresholds.…”

“…At high levels of chirp stimulus, desynchronization develops as a result of overstimulation on the cochlear basilar membrane. As a result, it is stated that the wave V amplitudes decrease (25)(26)(27). This effect can be observed, especially when a high stimulus level is sent to subjects with normal hearing (25,27).…”

“…Megha et al (25) conducted a study that researched the effects of noise using NB CE Chirp ABR and TB ABR. Similar to our research, in this study; the mean wave V latency evoked by 500 Hz NB CE-Chirp was found to be 2.45 (SD: 0.68) in the control group with normal hearing.…”

Standardization of calibration scheme in NB Chirp ABR Hearing Assessment: A Preliminary Study Based on Normal Hearing Soldiers

“…The narrowband Chirp (NB Chirp), a frequency-speci c (mid-frequency) sound stimulus signal obtained by limiting the frequency bandwidth based on Chirp, is applied to fsABR increasingly. Some studies demonstrated that NB Chirp ABR causes a better neural response than tone burst ABR (TB-ABR) [13,14,15,16] and is preferred for fsABR, but the results of studies on the correction value for TB-ABR cannot be applied to NB Chirp ABR due to the differences in the physical properties of the sound signal and the induced neural response between NB Chirp ABR and TB-ABR. Thus, it is necessary to correct NB Chirp ABR using other correction values.…”