  The speech auditory brainstem response (sABR) is an objective clinical tool
to diagnose particular impairments along the auditory brainstem pathways. We
explore the scaling behavior of the brainstem in response to synthetic /da/
stimuli using a proposed pipeline including Multifractal Detrended Moving
Average Analysis (MFDMA) modified by Singular Value Decomposition. The scaling
exponent confirms that all normal sABR are classified into the non-stationary
process. The average Hurst exponent is $H=0.77\pm0.12$ at 68\% confidence
interval indicating long-range correlation which shows the first universality
behavior of sABR. Our findings exhibit that fluctuations in the sABR series are
dictated by a mechanism associated with long-term memory of the dynamic of the
auditory system in the brainstem level. The $q-$dependency of $h(q)$
demonstrates that underlying data sets have multifractal nature revealing the
second universality behavior of the normal sABR samples. Comparing Hurst
exponent of original sABR with the results of the corresponding shuffled and
surrogate series, we conclude that its multifractality is almost due to the
long-range temporal correlations which are devoted to the third universality.
Finally, the presence of long-range correlation which is related to the slow
timescales in the subcortical level and integration of information in the
brainstem network is confirmed.
