Frequency-shifts (not pitch-shifts) two copies of a source signal by independent Hz amounts, one per ear — the same Hilbert-transform / single-sideband technique as the FreqShifter Mac app. Feed it your mic, or use the built-in tone generator for clean binaural beats. Use headphones either way.
Left ear
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Right ear
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Beat Δ
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Technique: computes the analytic signal (original + Hilbert-transformed / 90°-shifted quadrature component via a 129-tap FIR kernel), then multiplies by a rotating complex exponential at the shift frequency and keeps the real part. This shifts every frequency component by a fixed Hz amount rather than scaling them. In tone mode both ears start from the same pure carrier, so shifting them apart is mathematically the same thing a normal binaural-beat generator does with two separate oscillators — this just does it via the real DSP path shared with the Mac app and the mic input. Adds ~23ms of processing latency (inaudible as a delay). Large shifts on complex sound (mic mode) will sound a bit metallic since harmonics stop lining up — that's expected, not a bug.
Recent systematic reviews and meta-analyses (2024–2025) find a medium, fairly consistent effect of binaural beats on anxiety, pain, and some cognitive measures — strongest in perioperative/dental-anxiety settings, and better when listening starts before the task rather than only during it. That said, at least one line of evidence finds binaural beats aren't clearly better than plain music for relaxation, and none of this shows a mechanism as strong as the pop-science "instant brainwave entrainment" framing suggests — treat it as a mild, well-tolerated relaxation aid, not a substitute for sleep, anxiety, or pain treatment.
Carrier frequency matters more than most guides mention. Gerald Oster's original perception research found beats are only reliably heard below a ~1000Hz carrier, with the sweet spot around 400–500Hz, but the carrier that best matches a target beat frequency shifts lower as the beat gets smaller (his curve puts alpha-range beats around a 230–240Hz carrier and theta-range beats around 160–210Hz). The presets above use that curve for delta/theta/alpha; beta/gamma carriers are rougher extrapolations since the literature thins out there. Also worth knowing: the subjective "beating" sensation itself gets harder to perceive above roughly 25–30Hz difference regardless of carrier — so don't expect the gamma preset to produce an obvious pulse the way delta/theta do.
| Band | Beat range | Typical use | Suggested carrier |
|---|---|---|---|
| Delta | 0.5–4 Hz | Deep sleep | ~200 Hz |
| Theta | 4–8 Hz | Relaxation, meditation | ~185 Hz |
| Alpha | 8–12 Hz | Calm, alert focus | ~235 Hz |
| Beta | 12–30 Hz | Active concentration | ~300 Hz (approx.) |
| Gamma | 30–100 Hz | Peak performance | ~400 Hz (approx., weak evidence) |
Practical suggestions: use tone mode for anything you actually want to work as a "binaural beat" — mic mode shifts broadband real audio, which won't produce a clean beat frequency the way a single shifted carrier does, and is better reserved for the original experiment (holding a phone playing music/speech up to the mic). Keep early sessions to 10–15 minutes and moderate volume rather than assuming louder/longer is more effective. Skip this if you have a seizure disorder, and don't use it while driving or operating machinery. If pregnant or using a pacemaker, there's no specific contraindication found in this research pass, but check with a doctor first given the general caution around unstudied stimulus exposure.