Final answer:
Subcultures influence each other musically through a process known as cross-cultural or intercultural influence, a key concept in ethnomusicology, leading to the blending of styles and evolution of music.
Step-by-step explanation:
The sphere of musical interaction that occurs when subcultures influence each other in the shared process of musical exchange is typically referred to as cross-cultural influence or intercultural influence.
Subcultures, such as ethnic and racial groups, or more interest-based communities like punk or biker culture, have unique musical tastes and contributions that reflect their specific experiences and values. When these subcultures interact, they can influence each other musically, creating a rich tapestry of sound that draws from a variety of sources.
For example, punk music with its DIY ethos and rebellious lyrics has influenced and been influenced by other genres and subcultures, demonstrating a blending of musical styles and themes.
This exchange is crucial for the evolution of music, as it incorporates diverse perspectives and expands upon traditional boundaries set by any one culture. In the context of ethnomusicology, the study of these interactions reveals how music is not only a reflection of a culture but also a medium through which cultures can communicate, merge, and evolve.