I signed up for master DM classes with Alexis Smolensk and had the first of them today. I learned a great deal, and I am looking forward to the next one.
It came up that I am going to graduate school for musicology, and Alexis mentioned that I might be able to tackle the bard problem - talking about how music actually impacts people and how bard players can bring music to the table.
I have a number of gut-reactions and initial thoughts which need some time to incubate. But, I am in a position to talk about what music was like in the 1650s, the time period of Alexis' world. While musicians in the world of Prodigy (being roughly equivalent to the 13th or 14th centuries in Europe), but I think some of my conclusions from this discussion could be useful, later.
Since I don't have access currently to the New Grove Dictionary of Music and Musicians, I pulled out a music history survey textbook which will help us provide a general overview of the period.
Before we begin, I want to reiterate that I am talking about musical traditions in Western Europe, the ones for which we have documentation. Each geographic region would also probably have had its own 'folk' tradition, but the division between modern 'folk' music and other musical traditions did not exist.
The other caveat I want to make here is that much of what I'll talk about is high class music - the music the nobility would be making and hearing. At this point in history, common people would only hear music in church. The nobility were the only folks with enough capital to afford having musicians on staff for regular entertainment, and different courts would compete for the most famous musicians.
The idea, then, of an itinerant minstrel in this period is, in many ways, totally baseless. What did exist were Romani bands, some of which did function as travelling performers, but most bands traveled to find a new place to settle (having been exiled from their previous home), bringing some of their music with them. In the 19th century, as each of the major European powers struggled to define their 'national character' (and a large part of that was their 'national musical style'), Hungarian music was almost exclusively played by the Roma communities who arrived there at the beginning of the 15th century but claimed by the ethnic Hungarians (the Roma, it was said, had 'borrowed' the music from the Hungarians). I think it would be fair to say that similar dynamics appeared in the mid-17th century, although at that time the idea of 'owning music' was, for the most part, ludicrous.
Our three models, then, for musicians in the 1650s are the court-supported professional musicians playing consort/chamber music and opera, the Roma or Roma-like musicians playing in what could be considered a 'folk' tradition, and the kapellmeisters (musicians supported by the Catholic or Lutheran Church, depending upon geography).
The Roma-style musicians are the closest to the romanticized ideal of bard expressed in most of the D&D source books that I have read. Some Romani would work as professional musicians at taverns or inns, playing the popular music of the area and expressing virtuosic skill. These individuals could read the general mood of a crowd to keep the audience happy. They typically played either solo or with a partner or two. At this point in music history, voice and instrument were considered equal (previously, vocal music was regarded as far superior to the artificiality of instrumental music), so these entertaining musicians would probably know how to sing and play a couple instruments (probably choosing between the violin-family, recorder and woodwind family, and some form of percussion (tambourine, bodhran, etc.)). Their skills, then, would have included learning new music quickly by ear and knowing how to change a preexisting piece to suit the audience listening to it.
This brings me to a good point that is often misunderstood by people thinking about music before the 19th century - until Beethoven, music was a trade, like carpentry or masonry. The elevation of music as a supreme art form did not occur until the 19th century - until then, music was expressly not art but entertainment (this had to do with the Church's taste-making power). At the beginning of the 17th century we have performer/composers working to make music reflect emotion (chiefly in the brand-new genre of opera with speech-like rhythms [Monteverdi's Orfeo], but also in non-liturgical polyphonic vocal music which used dissonance and consonance to bring meaning to the words [See Monteverdi's Cruda Amarilli]). Music was not seen, culturally, as an end in and of itself but as a way to make a living.
The court-supported professional musicians would have received several years of training in an instrument (I believe only one - a violinist would not have been trained to play the cello or harpsichord). Courts would not have an 'ensemble' - they would have independent musicians contracted to play with the court who would sometimes play music together, and while the singers would exclusively sing opera backed by the instrumentalists, the instrumentalists might play works based upon another composition's' melody(ies), improvisations (only for keyboardists and lute-players, as a solo), fugue-like pieces (works taking a single, new melody and constantly transforming it. This could be improvised (see J.S. Bach) on harpsichord or written out and played by a larger ensemble), pieces with contrasting sections (i.e. loud and soft, or woodwinds and viols), or dances (which sometimes were to accompany actual dances and other times works written in the same style with irregular rhythms which would make it challenging to dance to). Improvisation and the ability to compose were expected skills of all musicians, although some were more renowned for this than others.
The last group is that of the church musician, usually an organist (since instruments other than the organ were typically not allowed to be part of the Mass). These organists were highly skilled improvisers - J.S. Bach being the best of the best (although he appears somewhat after our time frame of 1650).
In short, when playing a bard with a European background, one has three choices - to be Roma, a former court-sponsored musician, or an ex-church musician. Due to the organ's lack of portability, the last one is probably unsuited for D&D play, but the first two would fit right in.
A Roma-style bard would be used to playing for people on the street. They would probably be completely ear-trained. Their music would seek to entice people to stay and listen, and they would need to be able to know what kinds of music would please the audience - they would play the music popular in a city, not what they had learned before.
A court-style bard would be used to playing for the upper classes and could read and write music. Unlike the Roma-style bard, the court bard would not have been responsible for picking and choosing repertoire, but they would be good at sight-reading and engaging with music on a more intellectual level - taking a single melody and playing it in many different ways. They would also be familiar with the more common pieces (dances, fantasies, etc.) of whatever geographic region in which they were last employed - each region of Europe was developing specific musical preferences, although Italian music was widely regarded as superior in every way.