## 4 Discussion
Our findings are also in agreement with observations indicating an age-related enhancement in sensitivity to frequency differences, whether in the context of pure tones or F0 [38; 39; 40]. This observed developmental pattern can potentially be attributed to the progressive maturation of temporal processing mechanisms [37]. Other studies suggest, however, that although, as a group, children may show immature temporal processing abilities, adult-like frequency discrimination thresholds [45] and VD thresholds based on F0 cues can be achieved in childhood [8]. This discrepancy can be explained by the notion that an ongoing process of maturation for temporal and central processing occurs in childhood. The maturational differences in F0 perception between the children and adults seemed to have led to different coping strategies when the formant cues were less accessible, i.e., in the presence of noise. For adults, F0 became the more salient cue, resulting in only a decline of about 35% (from 0.43 to 0.58 semitone) in VD when the combined F0 + formant cues were provided in the noisy conditions (comparing second VD measurements between quiet and noisy conditions). In contrast, children encountered a more significant challenge in noisy conditions, inefficiently utilizing both F0 and formant cues, leading to deterioration of about 74% (from 0.46 to 0.80 semitones) in VD with combined cues. Although the difference between the children and adults' VD in noisy conditions based on the combined cues was not found to be significant, potentially due to the large within-group variance for the children, this outcome may help clarify the difficulties children face when listening in noisy environments. A substantial portion, ranging from 25% to 55% of the observed variance in VD performance in noisy conditions, could be accounted for by the performance exhibited in quiet environments by both children and adults. This indicates a strong influence of the basic spectral and temporal processing mechanisms involved in VD under quiet conditions on the performance in noisy environments. These mechanisms encompass the cochlea's ability to resolve frequencies, which provides crucial information regarding the relationship between formant peaks in the spectral envelope of the speech signal [22; 23], as well as the temporal processing of intensity fluctuations over time in the speech envelope [25; 26]. However, an additional 75% to 45% of the variance in performance in noisy conditions was not explained by performance in quiet conditions. This variance may be attributed to higher top-down cognitive processes such as attention and short-term memory, which have a significant role in the formation of auditory objects and enhance stream segregation [66; 67]. Specifically, auditory attention could serve to extract the relevant spectral and temporal signal elements from the competing background noise, temporarily storing them in working memory to facilitate the discrimination task [68]. Subsequent investigations should consider exploring the correlation between VD in noisy conditions and cognitive capabilities of the participants. The combination of both F0 and formant cues yielded the best discrimination scores in quiet and in noisy conditions. That is, participants from both age groups benefitted from the integration of these cues, even though the formant cues were partly interrupted by noise. A possible explanation for this finding may be related to the fact that children acquire substantial exposure to the integration of these two vocal cues under impoverished conditions from a very early age. In everyday routine, children and adults often hear many voices embedded in background noise. Those are mixed into a unified acoustic stream, necessitating listeners to parse the desired speech from the obstructing background noise to facilitate successful communication. Accurate identification of the F0 and formant frequencies of the relevant talker aids in the segregation process and, thus, enhances speech recognition [69].