Hearing impairment often leads to a decrease in the auditory sensitivity or hearing dysfunction that prevents humans from sensing sounds in the environment. 

Auditory brainstem response (ABR) is an objective method via which hearing loss could be detected. ABR induced by click, a broadband signal, is generally considered as the gold standard. However, this traditional applied method has some limitations which might cause distortion and attenuation of acquired ABR waveform.  

The first one is due to the inherent delay of cochlear traveling wave, click cannot excite the entire cochlear basement membrane at the same time, leading to the attenuation of the induced ABR waveform. The second limitation is that the ABR measurements in the clinic usually adopt a fixed stimulation rate technique in which the late evoked response could contaminate the ABR signals and deteriorate the waveform differentiation after the averaging, thus compromising the overall auditory function assessment task. 

Leading by Professor CHEN Shixiong from Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, proposed a swept tone-based stimulus and a random stimulation method to solve these problems, the result has been published in Frontiers in Human Neuroscience.  

Swept tone stimulus that reconstructs the arrival time of different frequency components with respect to the delay characteristics of cochlear basement membrane was designed and used to solve the first limitation. The research team compared the performance of the proposed swept-tone-induced ABR method and the commonly adopted click induced ABR at different test levels and different stimulus rates. 

The obtained results showed that the waveform morphology of swept-tone-induced ABR was significantly better than that of click induced ABR across different test levels and stimulus rates. Moreover, compared to the click induced ABR at different sweeps, they found that the proposed swept-tone-induced ABR effectively induced the ABR waveform at a relatively faster rate. 

Random stimulation rate(RSR) method was proposed to solve the second limitation by introducing a random interval between two adjacent stimuli which made the unwanted part no longer synchronized with the stimulus onset, making these undesired parts canceled out each other after applying averaging technique.  

The results showed that the proposed RSR method was consistently repeatable and reliable in multiple trials of repeated measurements. The ABR waveforms of the RSR method showed better Wave I-V morphology across different stimulation rates and stimulus levels. The correlation coefficients as functions of averaging time showed that the ABR waveform of the RSR method stabilize significantly faster and therefore it could be used to speed up current ABR measurements with more reliable testing results. 

Professor CHEN expected: “These two methods can solve the attenuation and distortion of ABR signals from different aspects, and the future direction can be the combination of these two methods to further investigate their performance on clinical hearing detection technique. It is believed that the proposed swept tone approach and RSR method can provide new solutions to improve the sensitivity of ABR detection and potentially aid the adequate reconstruction of ABR signals towards a more effective means of hearing loss screening, brain function diagnoses and potential brain-computer interface.”  

CONTACT:

ZHANG Xiaomin

Email: xm.zhang@siat.ac.cn

Tel: 86-755-86585299