# Binaural beats and isochronic tones: a systematic literature review

- Type: research summary
- Study: Aparecido-Kanzler, Cidral-Filho and Prediger (2021)
- Stimulus: Binaural beats
- Design: Systematic review of randomized controlled trials
- Sample: 17 trials
- Evidence grade: Moderate evidence
- Original paper: Effects of binaural beats and isochronic tones on brain wave modulation: Literature review by Sandro Aparecido-Kanzler, Francisco J. Cidral-Filho, Rui D. Prediger (https://doi.org/10.24875/rmn.20000100)
- Summary by: Science Editor
- URL: https://sentiosonics.com/research/effects-of-binaural-beats-and-isochronic-tones-on-brain-wave-modulation-literature-review/

Aparecido-Kanzler and colleagues set out to collect every controlled trial of audio brainwave entrainment they could find. Searching PubMed, MEDLINE, LILACS and ScienceDirect for terms such as “binaural beats”, “isochronic tones” and “auditory beat stimulation” produced 674 records. After removing duplicates and off-topic papers they were left with 33 randomized controlled trials, which they scored with the Jadad scale. Seventeen trials scored three or better and were read in full.

Fifteen of those seventeen used binaural beats; only two used isochronic tones, which says something about how thin the isochronic literature is. Most of the included trials reported some effect of the audio on the outcome they measured, across anxiety, cognition, pain and mood.

The authors are careful about what that adds up to. They note that several positive findings rest on measurement tools that were not well matched to the intervention, and they recommend better-designed trials with analysis aimed squarely at the neurophysiological and behavioural effects of entrainment.

**Limitations.** This is a structured literature review, not a meta-analysis: it counts and describes trials rather than pooling their effect sizes. The Jadad scale is a coarse quality filter, the included trials are mostly small, and the review does not report a formal risk-of-bias assessment. Read it as a map of the trial literature up to 2020, and as evidence that the field is promising but under-tested.