Children's musical development begins in the prenatal period and continues after birth. It largely depends on the child's heritage, personality, desire, motivation, his family environment, and formal and informal education. It is important to provide children with a stimulating musical environment at an early age so that they can explore freely, discover their potential, and advance in the development of musical abilities. By conducting musical activities in educational institutions, progress can be made in the social-emotional, cognitive, and psychomotor development of children. The aim of this paper is to describe the musical and rhythmic abilities of children born early and to show their prenatal development. In addition, the paper presents the data and results of a case study based on the observation of sound and musical interests and reactions of fraternal twins T. and M. at the age of 10 to 14 months. In addition to the observation and analysis of the conducted activities within the framework of the case study, an interview with the mother was conducted before and after conducting the research. Mother B. states that from the very beginning she noticed an innate difference in interest and sensitivity to sound. Also, she points out that female fans like to listen to music because it soothes them. In an interview after the research, mother B. states that they both react much better to sounds, but that M. is still more sensitive to them. Also, he emphasizes that T. and M. react very well to the rhythm because when a song is sung to them rhythmically, then their attention is completely focused on the person singing. By observing the sound and musical interests and reactions of the twins over a period of 5 months, it was determined that when exposed to sound stimuli and performing games and musical activities, the twins T. and M. had different interests and reactions, but also that they but also that they were quite similar during certain months. The obtained results correspond to the research results of Richardson and Norgate (2005), who found that fraternal twins can perceive their environment differently and have different interests and methods of acquiring knowledge and skills.