A cochlear implant provides electrical pulses to neurons and is configured to convert the excitation signal into a sparsified signal for electrically stimulating the neurons, thereby reducing the redundancy of the stimuli applied to the neurons. A signal analyser is configured to perform dimension reduction or factorisation of said excitation signal in the time domain or in the frequency domain followed by a sparse transform, the resulting relatively clean output signal providing the input to an inverse transformation step to create the sparsified signal. The dimension reduction or factorisation can be performed by principal component analysis (PCA), and the sparse transform can be performed by independent component analysis (ICA).
