The study presents frication noise acoustic features of Polish dental voiceless sibilants (fricative /s/ and affricate /t͡s/) in the speech samples collected from 106 children (83 with normative dental articulation and 23 with disordered—interdental—articulation) aged 4;11–8;0. We aimed to 1) verify the differences between the characteristics of the frication noise accompanying these two sounds and 2) investigate the influence of interdentality on the frication noise features. The analysis employed features of the noise band (fricative formants, formant-related measures, and noise energies) and linear-mixed effect models. The results showed significant acoustic differences between the voiceless dental fricative and affricate. Experiments suggest that the place of articulation (dental/interdental) can also be distinguished based on the spectral features of the frication band; this finding may be employed in computer-aided speech diagnosis tools.