The objective of the present invention is to suitably
record ambient environmental sound and information related to hearing of a user at the time in order to collect data of a volume of data necessary for fitting at a
hearing aid store. This electroencephalograph is provided with a sound collection unit which generates sound data of sound of the outside, an
electroencephalography unit for generating brain wave data of
brain waves of a user, a classification unit for classifying the collected sound into a plurality of divisions which have been pre-defined in relation to
sound pressure, an accumulation assessment unit for assessing whether or not to
record the brain wave data on the basis of whether the number of times of data accumulation has reached a pre-set target value for the divisions into which the sound has been classified, and an accumulation unit for associating the brain wave data and the sound data and accumulating thereof if an assessment has been made to
record the brain wave data. A target value is set for each division so that when the target value of a first division, into which sounds of an expected minimum value are classified, is treated as a first value, and the target value of a second division, into which sounds of
sound pressure greater than the minimum value are classified, is treated as a second value, the first value is set so that the first value becomes greater than or equal to the second value for the accumulation assessment unit.