Little is known about the strategies that humans use to estimate the distance of a sound source. Variations in the sound pressure level and changes in the sound induced by its relationship with the acoustic environment have been proposed as important cues in the judgment of the apparent distance of a sound source. However, relatively little attention has been given to the role of frequency spectrum in the determination of auditory distance. In this work, psychophysical experiments on distance perception using auditory stimuli with different spectral characteristics are performed. The first series of experiments show that subjects perceive better the changes in the distance of the source for spectrally complex auditory stimuli compared to pure tones. In the second set of experiments, noise bands with bandwidths located on different parts of the frequency spectrum were used. From this experiment, the minimum bandwidth required for a sound signal in order to preserve information on the distance to the acoustic source is obtained as a function of frequency. These results show that the spectral characteristics of sounds can significantly influence the perception of the distance to a sound source.