The invention relates to a
system (1) and method for detecting malfunctions of the neurovascular
coupling of a user of a device that can be worn or implanted on the head, in particular a
hearing aid (2), long-term monitoring being carried out with the aid of a device worn by the user, in particular a
hearing aid. The device has a
signal processing unit (8) and a memory (16). The
system (1) also has at least two sensors (18, 20, 22), namely a sensor (20) for detecting brain activity and a blood sensor (18, 22) for detecting
blood flow to the brain. The at least two sensors (4, 18, 20, 22) are connected to the
signal processing unit (8) for transmitting sensor data (A, B), namely brain activity data (A) and
blood flow data (B). The
signal processing unit (8) is designed to process the sensor data (A, B) in such a way that characteristic data, in particular a characteristic value (K) for a correlation, in particular a time
delay between increased brain activity and
increased blood flow caused thereby, is determined, and reference characteristic data and in particular a reference characteristic value (RK) are formed therefrom over a relatively long
observation period (Z) as a measure of the time
delay Z. The reference characteristic data are compared with instantaneous characteristic data recorded later and a warning signal (W) is emitted in the event of an inadmissible deviation.