https://www.sciencedaily.com/releases/2020/06/200626114808.htm

"Brain activity produces neuronal oscillations that can be measured using electroencephalography," begins Anne-Lise Giraud, professor in the Department of Basic Neurosciences in UNIGE's Faculty of Medicine and co-director of the Evolving Language NCCR. These are electromagnetic waves that result from the coherent electrical activity of entire networks of neurons. There are several types, defined according to their frequency. They are called alpha, beta, theta, delta or gamma waves. Taken individually or superimposed, these rhythms are linked to different cognitive functions, such as perception, memory, attention, alertness, etc.

However, neuroscientists do not yet know whether they actively contribute to these functions and how. In an earlier study published in 2015, Professor Giraud's team showed that the theta waves (low frequency) and gamma waves (high frequency) coordinate to sequence the sound flow in syllables and to analyse their content so they can be recognised.