Unlike musical tones that are composed of the sum of a number of harmonically related sinusoidal components, pure tones only contain one such sinusoidal waveform. When presented in isolation, and when its frequency pertains to a certain range, pure tones give rise to a single pitch percept, which can be characterized by its frequency. In this situation, the instantaneous phase of the pure tone varies linearly with time. If a pure tone gives rise to a constant, steady-state percept, then it can be concluded that its phase does not influence this percept. However, when multiple pure tones are presented at once, like in musical tones, their relative phase plays a role in the resulting percept. In such a situation, the perceived pitch is not determined by the frequency of any individual component, but by the frequency relationship between these components (see missing fundamental).