The current invention discloses a portable brain-activity monitor for recording a subject's EEG while he/she is listening to music. The brain-activity monitor includes an earphone connected to a portable audio player as well as an EEG sensor. The EEG sensor is connected to EEG electrodes that are shaped and sized to fit within the auditory canal. Suitable electronic processing circuitry, located in close proximity to the electrode, amplify the EEG signals in a range of 0.5 Hz to 100 Hz, perform an analogue-to-digital conversion, filter the output and deliver it to a recording device. A cable connected to the subjects earlobe provides the ground for the EEG sensor. The monitor is preferably Bluetooth enabled to allow it to connect to computing devices such as PCs and smart phones.