Sound Lab

Breathing near six breaths a minute increases heart rate variability during the practice, according to a large review. Whether it lowers stress or anxiety in the long run is Emerging, and six per minute is a starting point, not a magic number.

When each ear hears a slightly different tone, you perceive a third, pulsing “beat” at the difference. A 2019 meta-analysis of 22 studies found a medium average effect on cognition, anxiety and pain perception, and noted that results depend on frequency, how long you listen and when. A later review of memory and attention found mixed results. Brain-wave bands themselves are well established as EEG patterns, but whether a beat in your headphones reliably moves you into one is not settled.

A review of 34 studies with 1,103 adults found no strong evidence that white or pink noise improves sleep, though pink noise looked more promising and no adverse effects were reported in the short term. For stress, meta-analyses find natural sounds tend to help more than quiet, with some inconsistency between studies. Water sounds and birdsong stand out in the research.

No single pitch has been shown to work better than another. The Solfeggio set (396, 417, 528 and so on) was popularized in the mid-1970s by Joseph Puleo, and we found no reliable evidence that these particular pitches do anything special. They are here because many people enjoy them. Choose the tone that feels calm to you.

Earth’s electromagnetic resonance near 7.83 Hz is real and measurable. That it tunes your body is Speculative. It is also far below the range of human hearing, so in the Lab it is offered as a beat between your ears, not as a tone.