Every sound, explained on its own page.
What each sound is, when it works, how to listen, and the research where it exists. All of them are in the Mindael app, free on the App Store. Choosing an app? See our comparison checklists.
Noise colors
Brown noise
Brown noise is the deepest of the noise colors: a soft, low rumble like a distant waterfall, with almost no hiss.
Noise centred on the mid frequencies, around 500 HzGreen noise
Green noise is a noise color with the lows and highs trimmed, leaving a band in the middle where most natural ambience lives.
Random noise, energy falls 3 dB per octavePink noise
Pink noise sits between white and brown: softer than static, brighter than a rumble, like steady rain.
Random noise, equal energy at every frequencyWhite noise
White noise is the bright, hissy member of the noise family, like radio static or a fan on high.
Nature and ambience
Ocean waves
Ocean waves are rain with a rhythm.
Natural broadband sound, close to a pink spectrumRain sounds
Rain is the most popular natural sleep sound for a reason: its spectrum is close to pink noise, it is steady without being mechanical, and almost everyone already associates it with staying indoors and doing nothing.
Binaural beats
Alpha waves
Alpha is the 8 to 13 Hz band, the rhythm of a brain that is relaxed and awake at the same time: eyes closed, nothing urgent, ready.
Binaural beat, 13 to 30 Hz difference (15 and 20 Hz in the app)Beta waves
Beta is the 13 to 30 Hz band, the rhythm of a brain that is awake, alert and working.
Binaural beat, 1 to 4 Hz difference (1, 2 and 3.5 Hz in the app)Delta waves
Delta is the slowest brainwave band, 1 to 4 Hz, the rhythm of deep, dreamless sleep.
Binaural beat, 40 Hz differenceGamma 40 Hz
Gamma, above 30 Hz, is the fastest brainwave band, associated with binding information together: the moment the pieces of a problem click.
Binaural beat, 4 to 8 Hz difference (4, 6 and 7.5 Hz in the app)Theta waves
Theta is the 4 to 8 Hz band, the rhythm of deep relaxation, drowsiness and experienced meditators.
Solfeggio frequencies
174 Hz
174 Hz is the lowest of the nine solfeggio tones, a deep hum close to the F below middle C.
Pure tone at 285 Hz, solfeggio scale285 Hz
285 Hz is a low, warm solfeggio tone a little above 174 Hz, traditionally paired with restoration and settling.
Pure tone at 396 Hz, solfeggio scale396 Hz
396 Hz is the first tone of the original six, traditionally paired with letting go of fear and guilt.
Pure tone at 417 Hz, solfeggio scale417 Hz
417 Hz is traditionally the tone of change: clearing what was and making room for what is next.
Pure tone at 528 Hz, solfeggio scale528 Hz
528 Hz is the most listened-to solfeggio tone by a wide margin: a warm mid tone near the C above middle C, called the love frequency in the tradition, and the one tone with a published study, where five minutes of music at 528 Hz lowered stress markers compared with standard tuning..
Pure tone at 639 Hz, solfeggio scale639 Hz
639 Hz is traditionally the tone of connection: relationships, communication and warmth toward others.
Pure tone at 741 Hz, solfeggio scale741 Hz
741 Hz is traditionally the tone of expression and solutions: speaking clearly, thinking clearly, finding the way through.
Pure tone at 852 Hz, solfeggio scale852 Hz
852 Hz is traditionally the tone of intuition and inner order, the last of the original six.
Pure tone at 963 Hz, solfeggio scale963 Hz
963 Hz is the highest of the nine solfeggio tones, traditionally paired with awareness and a sense of oneness.