The acoustic responses of a dynamical system reflect the characteristics of the external excitation and vibrating system. The objective in an identification problem is to characterise the system and excitation from the measured responses. This becomes challenging if the characteristics of the dynamical system are time-varying. The analysis of the acoustic signal generated as a result of the tyre-pavement interaction (TPI) is one such situation, where in order to study the time-varying nature there is a need to obtain the characteristics of the instantaneous response. This study explores the single frequency filtering analysis of signals to examine the time-varying characteristics of tyre-pavement interaction noise (TPIN). Field measurements of TPI acoustic signals were obtained for a two-wheeler driven at different speeds on asphalt and cement concrete pavements. The time-frequency characteristics of the tyre tread impact and of the air cavity resonances are analysed by investigating the effect of vehicular speed and pavement type on TPIN. The specific features of TPIN such as the harmonics due to periodic tread impact and the frequency response due to resonances of the air cavities are examined in detail. The analysis presented in this paper will be useful in developing methods for health monitoring of tyre and pavement systems.