Probably the single greatest turning point in music history was Thomas Edison's invention of the phonograph cylinder in 1877. This invention made it possible to record sound and play it back. Until then, music could only be appreciated through live performance. The continued development of sound recording and sound amplification technology has shaped the role that musical entertainment plays in today's culture.
In the pre-recording age (only live music) there were basically two types of musical entertainment. Large entities such as the church or ruling officials could afford to pay professional composers and musical ensembles. The great composers of the Baroque, Classical and even Romantic eras were commissioned through this method. The only musical alternative available for common people was folk or minstrel style performances. Traveling minstrels tended to be solo performers of a lower skill level when compared to commissioned artists. Folk music was also shared through what we would now call "jam sessions" as family and friends hung out and passed the time. I guess a third category could be the use of music in the military, although this form of music was not purely for entertainment. It also provided order, structure and intimidation.
The divide between folk and professional music caused a huge polarization of the role of music in historical society. Most wealthy people did not consider folk music to be "real" music. True musical concerts were limited occurrences that were looked forward to. By limited, I do not mean to say that concerts hardly ever took place. However, imagine a world where it is not possible to turn on an electronic device and listen to recordings of music. The only time that music could be enjoyed was during public performances. In addition, the only way to become a musician was to train under another professional musician (which required money and predisposed skill). Common people were locked out of this side of musical entertainment. They could only enjoy music by attending church (which also required money at times - corruption in the church) or through the "fiddling around" of untrained performers.
After the invention of audio recording and other developments in music technology, the appreciation of professional music has been made available to all. However, the definition of professional music has changes. It is no longer exclusive to the style and level that was set in the Classical era. Popular culture has infused with musical style to create a variety of musical genres. The study of musical performance and the ability to market music has shifted from an exclusive community to a pool of almost anyone. This change has turned musical entertainment into an entity with an endless variety of style selections and skill levels.
In addition, music is now available to listen to everywhere. As I mentioned earlier, one can just turn on an electronic device and listen to broadcasts or recordings. Plus, it is now possible to access free recordings of most music on the internet, so people don't even have to pay to own these recordings anymore. This shift has changed musical entertainment for something that was extremely select to something that is extremely common. It is even available in settings where people are not intentionally seeking to be musically entertained like elevators, hospitals and shopping malls.
Some would argue that this change is good because now everyone can appreciate music. Others may argue that this change is bad because it has devalued music. Rare items are always more valuable. We naturally have less appreciation for things that are readily available. In addition, we grow tired of things that we have been exposed to too often. The list of pros and cons is enormous on this topic. We could discuss skill level and the change in what is now accepted as professional. We could discuss variety of style and whether or not some styles should even be considered music. However, those (and other) topics will result in a post that is way too long. I simply wished to cause us to think about this change and how it has affected music. The ending to this thought happens in your mind. Please share your thoughts in the comments section if you wish to continue the discussion.