Disclosed is a device (2) adapted to detect lateral brainstem response states of a subject (1) over a period of time as a function of a population of neurons&rsquo； evoked response patterns to sound stimuli. The device (2) includes a sound stimuli generating unit (200) operative to repeatedly send, over the period of time, an identical sound stimulus to the subject to evoke the neurons response patterns. The sound stimulus comprises a first train of unmodified sound pulses and at least one second consecutive train of modified sound pulses. A detection unit (210) detects a brainstem response signal related to the neurons&rsquo； response patterns. A first brainstem response signal is caused by the first train of sound pulses and at least one second brainstem response signal is caused by the second consecutive train of modified sound pulses. Storage unit (220) stores information based on the brainstem response signals and a control unit (230) repeatedly, over the period of time, determine the lateral brainstem response states for each of the sound stimulus. The lateral brainstem response states are based on comparisons of the first brainstem response signal and the at least one second brainstem response signal of the sound stimulus.
