This paper presents a new method for the speech signal decomposition into periodic and aperiodic components. Proposed method is based on the Discrete Harmonic Transform (DHT). This transformation is able to analyze the signal spectrum in the harmonic domain. Another feature of the DHT is its ability to synchronize the transformation kernel with the time-varying pitch frequency. The system works without a priori knowledge about the pitch track. Unlike the most applications proposed method estimates the fundamental frequency changes within a frame before estimating fundamental the frequency itself. Periodic component is modelled as a sum of harmonically related sinusoids and for accurate estimation of the amplitudes and initial phases DHT is used. Aperiodic component is defined as a difference between the original speech and the estimated periodic component.