Akademik

delta rhythm
noun
the normal brainwave in the encephalogram of a person in deep dreamless sleep; occurs with high voltage and low frequency (1 to 4 hertz)
Syn: ↑delta wave
Hypernyms: ↑brainwave, ↑brain wave, ↑cortical potential

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ˈdelta rhythm 7 [delta rhythm] noun countable, uncountable (biology)
the normal electrical activity of your brain when you are asleep

Useful english dictionary. 2012.