A binaural beat is the perceptual pulsing tone the brain constructs when each ear receives a slightly-different pure tone. The beat's frequency is the absolute difference between the two ear inputs: fbeat = | fL − fR |. By choosing the beat frequency to fall inside a target EEG band you can attempt to entrain the brain to that band's typical activity — this is the basis of brainwave-entrainment audio.
Mode A vs Mode B
- Mode A (Beat → L/R) — pick a target beat and a base (carrier) frequency. The tool gives you the two ear frequencies needed. This is what you use when you've decided "I want alpha (10 Hz) entrainment using a base of 200 Hz" and need to know L and R.
- Mode B (L/R → Beat) — given two specific ear frequencies, what beat results? Use this when you have an existing recording or instrument tuning and want to know what brainwave band the beat falls into.
About the conventions
This tool uses the asymmetric convention (L = base, R = base + beat). Some calculators use the centered convention (L = base − beat/2, R = base + beat/2) which keeps the perceived pitch centered exactly on the base. Both work identically — the beat is the same in either case, and at typical base frequencies the perceptual difference between the two conventions is negligible.
Beat values outside the standard 0.5–40 Hz range
The tool accepts any positive beat value, but only beats inside 0.5 – 40 Hz produce the brainwave-entrainment effect. Above ~40 Hz the perceptual beat becomes harder to discern and starts merging with the ordinary auditory experience of two close tones. Below 0.5 Hz the variation is too slow to register as a beat — you just hear two pitches drifting in and out of phase over many seconds.
What's the relationship to the Binaural Beats Generator?
This is the math tool; the Generator is the audio tool. Use this to figure out what L/R frequencies you need, then open the Generator with those values to actually hear the result. The "Open in Binaural Beats Generator" button just navigates to the Generator — you'll need to enter the values there manually for now.
Why does the chart split bands at 8 Hz, 12 Hz, 30 Hz etc?
These are the conventional EEG-band boundaries used in clinical neuroscience for naming brainwave activity. Different sources use slightly different cut-offs (some use 7 vs 8 Hz between theta/alpha, or 13 vs 12 Hz between alpha/beta) — the differences are minor and largely cosmetic, since real brain activity doesn't respect sharp boundaries either. This tool uses the most common cut-offs from clinical EEG literature.
Is there a "best" base frequency for any given beat?
Research consistently uses base frequencies in the 100 – 500 Hz range. Below ~50 Hz the two tones approach the threshold where they fuse perceptually into a single pitch and the beat becomes muddy; above ~1000 Hz the binaural beat sensation weakens. Lower base frequencies (100–200 Hz) work well for delta and theta; mid-range (200–400 Hz) for alpha; higher (300–500 Hz) for beta and gamma. Default 200 Hz is a defensible middle ground.
My target beat is 7.83 Hz (Schumann). Why doesn't it round to exactly that in some tools?
Numerical precision. Many calculators store beat values as integers (rounded to 0.1 Hz) which would force 7.83 to 7.8. This tool uses arbitrary floating-point inputs so 7.83 is preserved exactly. The companion Binaural Beats Generator slider uses 0.01 Hz resolution to preserve the same precision in its UI.
What if my left frequency is higher than the right?
Mode B handles that by taking the absolute difference: the beat is the same whether you "put the higher tone on the left or right ear". In practice some sources argue there's a subtle asymmetry — that "high on left" feels different from "high on right" because of hemispheric brain processing — but this is debated and not well-established. For most uses, the beat magnitude is what matters.
Can I get gamma-range beats (over 30 Hz)?
Mathematically, yes — set the beat to 40 Hz and the calculator gives you f_L=200, f_R=240. Perceptually, the binaural-beat illusion weakens above ~30 Hz, so what you hear with headphones may be less like a slow pulse and more like a "rough" or "buzzy" combined sound. The 40 Hz target has the most research interest in the gamma range but the actual entrainment is less reliable than for slower bands.
What's the midpoint pitch in Mode B for?
It's the perceived "pitch center" of the binaural sound — informally, the "note" your brain hears the two tones as. Useful when you want to match the binaural beat to a musical pitch (e.g. tune the midpoint to A=440 Hz for compatibility with other instruments) or to a specific frequency in a recording.
Is the calculator's "above gamma" warning meaningful?
It just means the beat is faster than what the standard EEG-band naming covers (γ tops out around 100 Hz). Mathematically nothing is wrong; perceptually you're well outside the brainwave-entrainment range and into the territory of ordinary "two close tones beating together" auditory perception. For binaural-beat purposes stay within 0.5–40 Hz.