This article deals with the use of the human voice within the instrumentation process. It defines three basic situations in which the voice can be found: Dominant role of vocal part, The human voice as an equal partner to other instruments and The human voice and its timbre function. The text also mentions the human voice as an accompaniment to other instruments. The function of these approaches is demonstrated by the chosen examples of Arnold Schönberg´s and György Ligeti´s compositions. This contribution points to many factors which could be taken to consideration during composing. It marginally focuses on the connection between the timbre and emotions.