The "S" sound is typically one of the last sounds a child learns. This is partly due to the fact that its production requires very precise tongue tension. In the German language, there are two variants of the sound: voiced (humming) when following a vowel, and voiceless before a consonant and at the end of a syllable or word. The articulation of the hissing "S" sound often poses challenges for preschool-aged children. In technical terms, the difficulty in producing the "S" sound is referred to as sigmatism. Up until the age of four, issues with the production of the "S" sound are considered a normal part of language development and are not a cause for concern. At this stage, it is important that the child is able to distinguish the sound from others and that their oral musculature is developing appropriately for their age. By the time they start school, the child should be able to produce all sounds correctly.