A hearing aid system comprising - an acoustical-electrical transducer adapted for converting an acoustical input sound into an electrical audio signal; - a noise generator (101, 102) adapted to provide a noise generator output signal; - a signal splitter configured to split the noise generator output signal in at least N parallel branches; - N band-pass filters wherein each of said N branches comprises one of said N band-pass filters adapted to provide an output signal; - level modulating means adapted to control the level of the output signal from the band-pass filters, hereby providing level modulated band-pass filter output signals and further adapted to increase the level of the output signal from one of the band-pass filters while decreasing the level of the output signal from another of the band-pass filters; - first summing means adapted to sum the level modulated band-pass filter output signals from said N branches hereby providing a sound enriched sound signal; - harmonic controller means adapted to set the center frequencies of the band-pass filters in accordance with a predetermined musical scale and such that at least N-1 of the band-pass filter center frequencies are selected from N-1 different predetermined frequency intervals, and adapted to change the center frequency of at least one of the band-pass filters, in response to a trigger event; - timing controller means adapted to trigger the harmonic controller means to change the center frequency of at least one of the band-pass filters in response to the event that the level modulating means has increased a peak level of the output signal from one of the band-pass filters to a first predetermined level, or has decreased a peak level of the output signal from one of the band-pass filters to a second predetermined level; - second summing means for adding the sound enriched sound signal to the electrical audio signal hereby providing an electrical input signal; - signal processing means configured to amplify the electrical input signal in order to alleviate a hearing loss of a hearing aid user, hereby providing an electrical output signal; and - an electrical-acoustical output transducer for converting the electrical output signal into sound. - an acoustical-electrical transducer adapted for converting an acoustical input sound into an electrical audio signal; - a noise generator (101, 102) adapted to provide a noise generator output signal; - a signal splitter configured to split the noise generator output signal in at least N parallel branches; - N band-pass filters wherein each of said N branches comprises one of said N band-pass filters adapted to provide an output signal; - level modulating means adapted to control the level of the output signal from the band-pass filters, hereby providing level modulated band-pass filter output signals and further adapted to increase the level of the output signal from one of the band-pass filters while decreasing the level of the output signal from another of the band-pass filters; - first summing means adapted to sum the level modulated band-pass filter output signals from said N branches hereby providing a sound enriched sound signal; - harmonic controller means adapted to set the center frequencies of the band-pass filters in accordance with a predetermined musical scale and such that at least N-1 of the band-pass filter center frequencies are selected from N-1 different predetermined frequency intervals, and adapted to change the center frequency of at least one of the band-pass filters, in response to a trigger event; - timing controller means adapted to trigger the harmonic controller means to change the center frequency of at least one of the band-pass filters in response to the event that the level modulating means has increased a peak level of the output signal from one of the band-pass filters to a first predetermined level, or has decreased a peak level of the output signal from one of the band-pass filters to a second predetermined level; - second summing means for adding the sound enriched sound signal to the electrical audio signal hereby providing an electrical input signal; - signal processing means configured to amplify the electrical input signal in order to alleviate a hearing loss of a hearing aid user, hereby providing an electrical output signal; and - an electrical-acoustical output transducer for converting the electrical output signal into sound.