The Evidence Behind the Frequencies
FMB's sound journeys are built on the auditory steady-state response (ASSR) and a growing body of EEG/MEG research into dichotic, split-hemisphere sound entrainment. This page collects the citations referenced from "The Science."
← Back to FMBThe Science of Split-Hemisphere Entrainment
Mahajan et al., 2014 (PLoS ONE) and Lazzouni et al., 2010 (Clinical Neurophysiology). Two lab studies (23 and 15 adults; EEG and MEG) that played a different amplitude-modulated sound to each ear and recorded the brain's steady-state response. Responses were larger in the hemisphere opposite the stimulated ear, with same-side input suppressed. They measure brain responses to sound, not how people feel afterwards.
40 Hz Sound and Light Stimulation in Alzheimer's Disease
Cimenser et al., 2021 (Frontiers in Systems Neuroscience). A randomized, sham-controlled trial in 22 people with mild to moderate Alzheimer's disease (14 active, 8 sham). The active group received one hour a day of 40 Hz visual and auditory stimulation for six months; the sham group received similar stimulation not designed to evoke 40 Hz brain responses. The active group had fewer nighttime active periods and kept their daily-living scores, while the sham group's scores declined. It is a small trial in patients, it combines light and sound, and its authors call for larger and longer trials. FMB is not a treatment and does not currently ship light-based sessions.
Read → — 40 Hz Sound and Light Stimulation in Alzheimer's Disease
Binaural Beats and Creative Thinking
Reedijk, Bolders & Hommel, 2013 (Frontiers in Human Neuroscience). Twenty-four university students heard alpha and gamma binaural beats. Divergent thinking was affected, convergent thinking was not, and the effect depended on each person's estimated dopamine level (from eye-blink rate): people with low blink rates mostly benefited from alpha beats, people with high rates were unaffected or impaired. The authors conclude these methods aren't suited to a one-size-fits-all approach. It tests binaural beats — FMB uses monaural and isochronic beats.
Binaural Beats: A Systematic Review
Ingendoh, Posny & Heine, 2023 (PLoS ONE). Fourteen studies on whether binaural beats entrain brain oscillations: five in line with entrainment, eight contradicting it, one mixed. The authors call the results inconsistent, and say the studies differed too much in design to compare reliably. Included even though FMB doesn't use binaural beats — honest sourcing means showing where the evidence is thin, not just where it's favorable.
Monaural vs. Binaural Beats: Brain Responses
Schwarz & Taylor, 2005 (Clinical Neurophysiology) and Pratt et al., 2010 (Hearing Research). Two lab EEG studies comparing beats that are physically in the sound with binaural beats: the physical beats evoked larger brain responses (at 40 Hz in the first study; at 3 and 6 Hz in the second). One reason FMB builds on monaural and isochronic beats. It measures brain response, not how people feel.
Schwarz & Taylor → — Monaural vs. Binaural Beats: Brain ResponsesPratt et al. → — Monaural vs. Binaural Beats: Brain Responses