Alpha-EEG/EMG neurofeedback combined with binaural beats stimulation: A randomized placebo-controlled within-subject cross over study

Both neurofeedback training (NFT) and binaural beat stimulation (BBS) are promising non-invasive neuromodulation techniques. NFT aims to enhance self-regulation by providing real-time feedback on brain activity, while BBS is thought to entrain brainwaves through auditory stimulation. Although both methods target similar outcomes, such as improved well-being and cognitive function, their potential interactive effects when combined remain largely unexplored and theoretically uncertain. This study empirically investigated the possible interference or synergistic effects between NFT and BBS. Twenty-two healthy adults participated in a randomized, placebo-controlled, within-subject crossover study. The protocol included six 15-minute trials: baseline, NFT alone, pure-tone sound stimulation (400 Hz), BBS alone, NFT combined with sound, and NFT combined with BBS. The BBS was individually generated by modulating a 400 Hz carrier tone with the participant's own EEG recorded during successful NFT periods. Primary outcomes were Global Vigor (GV) and the Self-Regulation Learning Ability Index (SLAI). Secondary neurophysiological outcomes included individual alpha peak frequency (iAPF), alpha-2 power, and frontal integrated EMG (IEMG). When applied separately, both NFT and BBS significantly improved outcomes compared to baseline (e.g., increased GV, SLAI, iAPF, and alpha power, and decreased IEMG; p ≤ 0.025). There was a significant interaction between the factors of NFT and BBS. The combination of NFT with BBS led to a significant decrease in SLAI, iAPF, and alpha power (p < 0.007) compared to NFT alone, while GV remained unchanged. Although BBS alone can positively influence well-being and self-regulatory ability, its simultaneous application during NFT disrupts the training efficacy.