Objective: The purpose of the research was to examine and measure singing accuracy, intonation and quality of the singing voice of children aged 10-14 and explore the impact of structured warm-up exercises on children’s singing voices. A further aim of the study is to investigate the effects of the movement, imagination, and targeted instructions used during warm-up on children's singing voice.

Methods: 60 children aged 10-14 participated in the study, singing in children's choirs. Self-developed instruments were used to assess the accuracy, intonation and quality of the children's singing voices. The research methods employed were rating scales and analysis of video recordings of children singing. Data were analysed using qualitative and quantitative analysis protocols (Likert scale, descriptive statistics, Pearson correlation).

Results: A well-structured warm-up has a significantly positive effect on singing accuracy, intonation and quality. The movement exercises at the beginning of the warm-up are necessary to develop the correct posture, which creates the right conditions for deep breathing and activation of the diaphragm. The different types of singing exercises should take into account children's singing voice formation problems and use appropriate consonant and vowel combinations to correct them. Imagination, using images and metaphors, is essential in improving the singing voice quality and intonation. The targeted instructions greatly help children to achieve natural, correct singing voice formation.

Conclusions: The development of singing accuracy, intonation and the singing voice quality are closely linked. The warm-up should be deliberately structured, with the exercises following each other in a specific order. A warm-up combined with movement and imagination is beneficial for developing children's singing voices. When planning the warm-ups, it is essential to consider the children's possible vocal production problems and plan the warm-up with this in mind.