Neural Entrainment
https://www.sciencedirect.com/science/article/pii/S0378595510000262
EEG processing began with segmentation of the continuous EEG to epochs beginning 100 ms before until 2300 ms after each tone burst onset. Eye movement correction (Attias et al., 1993) and artifact rejection (±150 μV) followed segmentation. Average waveforms were then computed for the 3 and 6 Hz beats in the 250 and 1000 Hz base frequencies of each beat type (binaural and acoustic beats). Consequently, between 300 and 350 repetitions were averaged to obtain the potentials evoked by each stimulus condition. These 8 separate averages (2 Beat Frequencies × 2 Base Frequencies × 2 Beat Types) were computed for each subject, as well as across subjects to obtain grand mean waveforms. After averaging, the data were band-pass filtered (FIR rectangular filter with a cutoff at 2–10 Hz) and baseline (average amplitude across the 100 ms before stimulus onset) corrected. This filter was chosen to enhance the detection of the beats-evoked oscillations and was found to have only a minor effect on the amplitudes of the onset-evoked potentials. This minor effect was common to all onset responses and hence did not affect the comparisons across conditions that were conducted in the waveform analyses.
P50 and P200 are the first two positive ERP waves, and other papers have shown that response onset is about 200 ms.
https://journals.physiology.org/doi/full/10.1152/jn.00224.2014
Response latency for maximum value of cross-correlation (figure 7) was ~75 ms for 10 Hz.
Vernon and colleagues applied binaural beats in the alpha (10 Hz) and beta (20 Hz) frequency ranges for 1 min duration over ten trials to evaluate whether a frequency following response (FFR) could be elicited to these frequencies in two separate participant groups. Each trial was interleaved with exposure to a pure tone played at 400 Hz while EEG was recorded from the left and right temporal regions. The authors observed a slight decrease in resting baseline amplitudes for both beat frequencies, from the pre- to post-entrainment and during the experimental session, and participants exhibited reduced alpha activity during the binaural beat on-phase compared to the off-phase (36). In a similar study, Gao et al. (37) investigated the effects of binaural beats applied for a 5 min duration at 1, 5, 10, and 20 Hz. To detect EEG changes due to binaural beats, they analyzed relative power (RP), phase locking values (PLVs), and cross-mutual information (CMI). Relative power in the theta and alpha bands increased during delta and alpha binaural-beat frequency stimulation while it decreased in the beta band. During alpha and delta binaural-beat stimulation, reduction in CMI was detected among right temporal, frontal, and occipital areas 3.5 min after stimulation onset. However, during beta-beat stimulation, an increase and subsequent decrease in CMI was observed – this occurred between the left temporal and frontal areas (increase), and between right temporal and centro-parietal areas (decrease), and in the case of theta beat stimulation, an increase over left temporal and central cortical areas was observed. These data suggest that application of binaural beats in theta, alpha, delta, and beta frequencies is able to alter functional connectivity between brain regions (37).
Clinical Neurophysiology ~ 200 mS latency to "steady state" response.
PLoS One article looking at high-density EEG in theta and beta frequencies, good intro and methods.
Science article from 1970 showing that neural entrainment (or "frequency following response") is a neural phenomenon rather than artifact.
Psychological Research Meta-Analysis from 2018 showing a Hedge's g value of 1 for analgesia based on three studies between 1999 and 2010 (The Hedge's g statistic expresses the difference of the means in units of the pooled standard deviation)
EEG pre-processing from EEGLAB