The research notebook.

Binaural, monaural, and the morph between.

Nighthawk Tube runs two oscillators a few hertz apart. What reaches your ears depends on the BEAM switch, and the difference matters more than most beat apps let on:

What the evidence says, and doesn't.

The app describes the stimulus, never an outcome. Here's why that grammar is the honest one.

Solid

The beat percept itself is thoroughly established (Oster 1973). Monaural beats evoke a much larger measured auditory steady-state response than binaural, the most consistently replicated finding in the area (Draganova 2008, Orozco Perez 2020).

Modest but real-ish

A meta-analysis across 22 studies found an overall effect of g = 0.45 for anxiety, cognition and pain, with no detectable publication bias; longer exposure did better (Garcia-Argibay 2019). A 6 Hz beat study reported d = 0.58 on state anxiety (Chaieb 2017).

Contested

"Entraining your brainwaves" as a literal mechanism is not established: a systematic review found 5 of 14 EEG studies supporting entrainment and 8 against, with zero support in the beta band (Ingendoh 2023). A 2025 parametric EEG study (n = 64) did find elevated power at the beat frequency, while the beats did nothing for the attention task they were meant to help (Scientific Reports 2025).

The newest bridge

A 2026 study had listeners hear drumming at delta, theta and alpha rates: neural tracking at 4 Hz predicted the intensity of altered experience (ρ = 0.39) (Scientific Reports 2026). Drumming is amplitude modulation, the monaural stimulus, not the binaural one, which is why the app's 4 Hz Pulse preset ships in FUSE. Shamanic traditions have drummed near this tempo for a very long time; that's an observation, not a claim.

Nine rhythms, each with a reason.

Carriers sit in the 250–450 Hz region where the binaural percept is most salient; two ride at 340 Hz, the best-performing carrier in the 2025 parametric study.

Four charts, no canon.

Ask the internet for "chakra frequencies" and you get four mutually incompatible answers. They disagree about every chakra, because they come from four different places.

Where each chart comes from

The diatonic mapping, one note per chakra, C at the root, is a 20th-century Western construct, assembled between Leadbeater (1927), Hills (1977) and Judith (1987), with pitch assignments arriving later from the crystal-bowl trade. The classical sources (Ṣaṭ-Cakra-Nirūpaṇa, 1577) specify seed syllables, petal counts, elements, and no frequencies whatsoever. Even the rainbow colors are modern (the Theosophical account).

Solfeggio comes from a 1970s numerological reading of the Book of Numbers (history; a skeptical audit). The syllable names are genuinely medieval; the Hertz values are not, and the set isn't a scale in any tuning system. Nighthawk doesn't ship it.

Cousto's Cosmic Octave (1978) is the chart with actual arithmetic: take a natural period, invert it, and octave-double into the audible range (the full table). The Earth's year, 31,556,736 seconds, doubled 32 octaves lands at 136.10 Hz, remarkably close to the classical tampura drone. Because the tones come from orbital mechanics rather than a scale, the set can't be named by pitch class at all (why the charts collide).

BREATHE: a pacer that isn't a screen.

ORBIT's rotation has two tempos. DRIFT is the original slow turn. BREATHE locks the orbit to a 10-second cycle: six breaths a minute, the rate the slow-breathing literature centers on.

Slow-paced breathing near six cycles per minute is the active ingredient in most heart-rate-variability training: a meta-analysis of HRV biofeedback found large effects on stress and anxiety (Goessl 2017), and controlled comparisons suggest the paced breathing itself does most of the work, with or without the biofeedback display (Laborde 2022). Every paced-breathing app is a circle you must watch. Nighthawk's pacer is a sound moving around your head, eyes closed, no screen required, with the beat riding inside the orbit.

Session lengths, from the exposure literature.

Study exposures run about 5–33 minutes, with longer generally doing better and starting before the target activity beating starting during it (Garcia-Argibay 2019). The timer ladder (1 · 5 · 10 · 15 · 20 · 30) spans that range; twenty minutes is the canonical sit. The free tier's 5-minute sessions sit at the bottom of the studied range: a taste, honestly labeled.

References.

Auditory beats

• Oster (1973). Auditory Beats in the Brain. Scientific American 229(4)
• Schwarz & Taylor (2005). Human auditory steady state responses to binaural and monaural beats. Clin Neurophysiol
• Draganova et al. (2008). Cortical steady-state responses to central and peripheral auditory beats. Cerebral Cortex
• Pratt et al. (2009). Cortical evoked potentials to an auditory illusion: binaural beats. Clin Neurophysiol
• Chaieb et al. (2017). The impact of monaural beat stimulation on anxiety and cognition. Front Hum Neurosci
• Orozco Perez, Dumas & Lehmann (2020). Binaural beats through the auditory pathway. eNeuro
• Garcia-Argibay, Santed & Reales (2019). Efficacy of binaural auditory beats: a meta-analysis. Psychological Research
• Ingendoh et al. (2023). Binaural beats to entrain the brain? A systematic review. PLOS ONE
• López-Caballero & Escera (2017). Binaural beat: a failure to enhance EEG power and emotional arousal. Front Hum Neurosci
• A parametric investigation of binaural beats (2025). Scientific Reports
• Neural tracking at theta predicts drumming-induced altered states (2026). Scientific Reports
• Aparicio-Terrés et al. (2025). The neurobiology of altered states induced by drumming. Ann NY Acad Sci
• Martorell et al. (2019). Multi-sensory gamma stimulation and Alzheimer's-associated pathology. Cell

Breath & heart

• Goessl, Curtiss & Hofmann (2017). HRV biofeedback for stress and anxiety: a meta-analysis. Psychological Medicine
• Laborde et al. (2022). Slow-paced breathing at six cycles per minute, with and without HRV biofeedback. Psychophysiology

Chakras & tunings

• Ṣaṭ-Cakra-Nirūpaṇa (Purnananda, 1577), trans. Woodroffe
• Wallis. The Real Story on the Chakras
• Theosophical Society. The Rainbow Body
• Yoga Basics. Chakra colors (Leadbeater → Hills)
• Cousto. The Cosmic Octave tuning forks, full table. Planetware
• Planetware. The Earth-year tone, 136.10 Hz
• Solfeggio.dk. History
• Sound Meditation Presents. Solfeggio mythologies, busted
• Sound Healing LAB. Why chakra and planetary charts disagree

Safety

• Fisher et al. (2022). Visually sensitive seizures. Epilepsia
• WHO. Safe listening

Nighthawk Tube is an instrument for listening and calm focus, not a medical or therapeutic device. Band labels and preset lore describe the stimulus and what studies reported, never a promised effect.