Period Instrumental Music
Here's an experiment worth trying: watch any movie with Exciting! Action! Scenes! (the horror genre works best), but hit the MUTE button and experience it by reading the subtitles and seeing the action. You'll probably notice that it's a lot less exciting and the cat-out-of-the-box scares are rather less scary. That's because you're depriving yourself of one of the key cues: the music. It's a rare director who can make a good silent horror scene or movie; most movies rely on tense music to build up the moment, so when the cat does leap out of the box, you're already on an adrenaline rush. The bottom line: music makes the scene.
I've talked about vocal music elsewhere. This is a page about instrumental music. I'm guessing that in the real middle ages, you were less likely to hear music than you are today (especially since we hear a lot of spillover music: e.g., the guy trying to go deaf by his 21st birthday, the girl in the upstairs apartment who broke up with her boyfriend and puts "Can't Live Without You" on repeat, not to mention television and radio commercials). However, our perceptions of the middle ages have been colored by the music in movies and shows, so we expect to hear music. But walk into a random event, and chances are good you won't hear any instrumental music, except as a special performance. If you want to hear music at a medieval event, you have to go to a Renfair.
Why is that? I believe that it's a simple matter of economics. You can try just about anything in the SCA and until you decide you want to spend serious money, you can generally get along with very minimal monetary investment in equipment. Garb? You can get by on loaner garb for your first few events (chances are good your first event was a friend throwing clothes at you and saying "Here, put this on, we're going somewhere...") Brewing? You'll need a waterlock ($2), yeast ($1), and a bottle (potentially free, if you recycle) to start. Fighting? Except for the athletic cup (which, for some reason, no one wants to share...), you can go to fight practice for quite a while and get by on loaner armor.
Instrumental music, on the other hand, suffers from a lack of loaner equipment. Part of the reason is that for any musician, the instrument they play is part of them, and they're uncomfortable letting others touch it. Part of the reason is that you don't actually want to loan out most instruments: no one wants to loan or borrow a flute. So unless you already have the equipment, you've got to go out and get your own...and musical instruments aren't cheap and (unlike armor) can't easily be made by the novice.
There are several solutions. One is to bring whatever instrument you do play into the SCA, and play period music on it. A lot of folks do that, and as long as you're not bringing something obviously modern (like an electronic keyboard), most people take it for what it is: an attempt at period recreation. However, not all of us have that luxury: it's one thing to bring a flute, another thing entirely to bring a piano. Thus, this page is for those interested in playing period music, but who don't already play a period or perioid instrument: in other words, you're interested in music, but know you'll have to learn a new instrument and aren't sure what to try. What I've done below is listed some relatively inexpensive modern instruments which are reasonably similar to period instruments. My suggestion is that if you're interested, try the modern versions first and see if you enjoy playing them; if you don't, you haven't wasted a lot of money.
A qualifying statement: This is based on my own research, and unless noted, I haven't yet confirmed all the statements below. The only instrument I've had anything resembling formal training on is the piano, so I can't speak to the differences between modern and period performance techniques; obviously, this will have a big difference on how the instrument sounds. I've arranged these instruments by the price of an entry-level instrument (which is to say, the price I paid for them when I bought mine through a certain internet bidding company).
For those who want to have some fun, here's the start of the woodcuts from Praetorius's Syntagma Musicum (1619, though this version is from an 1884 printing), and Agricola's Musica Instrumetalis (1528/1545, from an 1896 printing). Praetorius gives detailed descriptions of a lot of musical instruments, and the woodcuts show you what he's talking about, and more detail about a broad range of Medieval and Renaissance musical instruments from Musica Antiqua's website. Edinburgh University has a nicely organized collection of musical instruments from different periods,and the Grinnell College Music Instrument Collection website shows the evolution of various instruments. The following list is somewhat biased: I can play strings and keyboards, but have difficulty with woodwinds and brass. By far the best collection I've found is that at the Metropolitan Museum of Art; I also consider their website to be by far the best museum website.
Some Basics of Music Theory
I've written this so you don't need a lot of musical training to get started. However, those who have some musical training may appreciate the following. One of the main issues of music in the western tradition is what constitutes a consonance. Classical music theory (dating back to Pythagoras) holds the consonances are connected to the existence of small whole number ratios. The acceptable ratios were 3: 2 (which corresponds to the interval of a fifth, for example C-G) and the ratio 4: 3 (which corresponds to the interval of a fourth, for example, C-F). The interval between the two higher notes (F-G) is a tone, and corresponds to a 9:8 ratio. Both mathematically and perceptually, the tone is dissonant.
Against this theoretical position was a purely practical one: the intervals are very large, and there are other intervals that sound consonant. In particular, the third (C-E) sounded pleasant. From a Pythagorean point of view, the third corresponded to an 81: 64 ratio, which is dissonant. However, this is very close to 80: 64 = 5: 4, which satisfies the requirement of the ratio being between small whole numbers. Starting in the Roman period, there was increasing acceptance of the third as a musically consonant ratio.
Notation
One of the great inventions of western civilization is musical notation. Originally, musical notation consisted of neumes, which indicated the relative pitch of notes in a musical piece. These are essentially reminders, to the performer, of whether the pitch rises or falls. Guido of Arezzo (fl. 11th cent.) is credited with the idea of identifying specific pitches. From lowest to highest, these were ut-re-mi-fa-sol-la. The names were taken from the initial syllables of words in a hymn to Saint John (where the corresponding words were to be sung at the corresponding pitch). Somewhat later, "Ut" was changed to "do", and "si" (from Sancte Iohannes) was added; in the 19th century "si" was changed to "ti", which gives us the modern do-re-mi-fa-sol-la-ti. Guido also introduced the four (later five) line staff to represent the notes.
The staff allowed the pitch of the notes to be recorded. The duration was recorded through several techniques, though two are particularly important. The first (common during the 14th and 15th centuries) is often referred to as "black mensural notation," which indicate the length of a note by varying shapes of a blackened quadrilateral. In the 15th and 16th centuries, white notation appeared; the major difference between modern musical notation and white notation is that the notes are squares with a diagonal oriented vertically and the stem originating at the apex, rather than elliptical with the stems running through the end of the major axis (I am a mathematician...).
In all of this, one important feature must be noted: A lot of music was never written down. The status of the performing musician was low enough (and that of the instrumentalist even lower) that until the Renaissance, very few treatises dealt with their work. Most historians believe that, as in modern jazz, a lot of instrumental performance was improvised.
The Players
As noted above, instrumental players tended to rank fairly low on the social scale (the one exception being trumpeteers, owing to their association with the court). The troubadours, perhaps the best-known of the medieval musicians, were not actually instrumentalists; in fact, the etymology of the word indicates that they were composers first, performers second. In terms of social acceptance, the rough ranking was: music critic, composer, vocalist, instrumentalist. Pure instrumentalists were viewed with particular suspicion: if you think about it, there is something very disturbing about the fact that someone can affect your emotional status without saying a word (see the note above on watching scary movies).
At the same time, it was acceptable for persons of a high social rank to be musicians and composers. Castiglione notes that the ideal courtier must not only be able to appreciate music, but should be able to play as well. William IX of Aquitaine was one of the early troubadours. Probably the best-known example of King Henry VIII of England, who was a skilled lutenist, and composer. He wrote a number of pieces, which did not include "Greensleeves.' To my ear, most of Henry's pieces are fairly pedestrian: they're reasonable pieces, but it was a good thing he had another job...his daughter Elizabeth was also a competent player on an instrument called the virginal (a form of the harpsichord).
Classification
Modern instruments are often classified into four basic types: percussion, wind, brass, and string. This classification system works well...if all you're talking about are drums, flutes, trombones, and violins. Most instruments fall into two categories, or between categories. For example, a piano's sound comes from striking a string: does this make it a string instrument or a percussion instrument?
Medieval and Renaissance classification was much more pragmatic: they distinguished between haut ("high", but taken to mean "loud") and basse ("low", but taken to mean "soft).
Recorders
I'll start with this one, as the recorder was the first musical instrument I learned in the SCA. You can get a cheap recorder for $5. You can get a really cheap recorder at most dollar stores. The five-dollar records look reasonably period (they're plastic, but from a distance, a myopic person would assume they were made out of horn or ivory). The really cheap recorders are one-piece extruded plastic, often in day-glo colors. I don't recommend them, but if you want to try-but-not-inhale, they might be fun to play with.
On the right is a page from Agricola, showing four different instruments he calls a "floten." For those with a little knowledge of German, that translates as "flute" (cf. Mozart's Zauberflote). However, looking at the shape of the top end, it's clear that these are what we would classify as recorders.
The difference between the two is that in a proper flute, you blow across an opening, but not directly into the instrument. It takes quite a bit of practice to get your airflow control to the point where you can make a noise, so proper flutes take some time to learn. In a recorder (sometimes called a ducted flute), you blow directly into the instrument, and there's a mechanism at the top which essentially takes up the work of governing the air flow. Consequently, recorders are much easier to learn.
Flutes
On the right is another page from Agricola showing flutes proper ("fifes", if you read down the side). Notice that these are very different from what we consider a flute; the modern "concert flute" is a 19th century invention. These are actually closer in style to the cheap bamboo flutes you can buy in Chinatowns around the country. I've never been able to get good sounds from them, but it's not entirely clear which end of the mouthpiece is responsible for this problem...
Violins and Fiddles
Absolutely period, in a broad range of shapes and sizes (see the illustration on the right). According to several websites I've visited rating the difficulty of playing musical instruments, violins are actually very easy to learn (!). I can't speak to whether or not this is true, since I don't play any bowed stringed instruments. The illustration from Praetorius (on the right) shows several of these.
Instruments 1 and 2 (Kleine posche) are versions of what is known as a rebec: a three-stringed bowed instrument. The Bulgarian gadulka is physically very similar to the rebec, though it usually has more strings; you can get these commercially.
Dulcimers and Travel Guitars
In the illustration to the right, take a close look at instrument number 8, known as a scheitholt. It's about as simple as a stringed instrument can be: it's a fretted soundbox with three or four strings. There's an implication it was originally a teaching instrument: something you could cobble together easily and if it broke because a student wasn't careful...no great loss.
There is a modern instrument called (variously) a mountain or Appalachian dulcimer, which shares many similarities with the scheitholt as a four-stringed instrument. However, the soundbox has a very different shape, either a sinusoidal or a teardrop shape. The shape is actually closest to what's sold as a backpack travel guitar, but that has six strings.
Bugles and Trombones
On the right is Praetorius' page on a variety of blown instruments. You can see trombones in various sizes (known as posauns; another term is sackbut). I don't play any brass instruments, so I can't speak too authoritatively, but my understanding is that brass instruments have no reeds and change their notes either by variations of air flow (the trumpet, as in number 10 and 11) or by changing the length of the resonating chamber (the posauns, numbers 1 through 4).
Shawms
One of the more common medieval instruments was the shawm, a double reeded woodwind instrument that subsequently developed into a broad range of woodwind instruments including the oboe (which didn't appear until the 17th century, under the name hautbois, literally "loud wood").
The shawm apparently evolved from the Middle Eastern zurna, which is commercially available today. I'm not a woodwind player, so I can't say too much else about this, except that the zurna is physically similar to a shawm, and is also a double-reeded instrument. Note that many players consider double reed instruments like the oboe and the shawm to be extremely difficult to play well.
The Ukulele, Guitar, and Mandolin
A number of plucked string instruments existed in period, but beware: while instruments called the gittara, mandola, zithern, and the like existed, they might not bear any resemblance to the modern guitar, mandolin, or zither. Remember: words change their meaning over time.
Very roughly speaking, period plucked string instruments were 1) small, 2) had paired strings, and 3) not many of them. That's about as useful as generalization as "knights wore armor," so here are some specifics.
The quintessential medieval plucked string instrument is the lute. This had a variable number of strings (but 12 was fairly common; this is the major exception to the "few strings" rule), strung in pairs. You can actually buy Renaissance lutes today, though you'll pay at least $1500 for them. The lute spawned a number of other instruments.
My extensive research indicates that the ukulele (properly pronounced, by the way, as "ook-uh-lay-lee") derived from a fifteenth century four-stringed fretted Portuguese instrument known a cavaquinho. I haven't been able to locate any pictures of one, so I won't say much more.
The guitar is the most common relative of the lute. Strictly speaking, the 6-string guitar is not a period instrument; the oldest ones only go back to the early 1700s (and for a long time were derided as instruments for the dabblers, not for serious musicians). Most of the very early guitars were strung in pairs, and had 4 or 5 courses. What makes the guitar interesting is that you can find images of instruments that, at first glance, look very much like guitars: take a look at the woodcut to the right, from the frontispiece of El Maestro by Luis Milan (1500-1561?).
At first glance, it looks like a modern guitar, with some changes: the position and number of the soundholes,in particular. But take a closer look at the headpiece: there are too many tuners (I count ten). The instrument appears to be an illustration of a vihuela. Surviving instruments have six pairs of strings, very much like a modern 12-string guitar. Note that there is a modern instrument called a vihuela, used by mariachi bands. The modern vihuela, however, only has five strings.
There are other differences between a modern 12-string guitar and a vihuela. The major one is the tuning: the period vihuela's strings were tuned E-A-D-F#-B-E (which corresponds to the tuning of a 6-course lute: anything you can play on a 6-course lute you can play on a vihuela) with both strings in a pair tuned to the same note, with the highest string often single; this is in contrast to the modern 12-string, where the two strings of a pair are generally tuned an octave apart. The strings were gut; you'll probably want to use nylon (mainly to save your fingers...remember, no plectrum).
The Others
There's a bunch of other instruments I won't include here, because while they are period, they represent a significant monetary investment, or are simply too difficult to transport. They include the harp, hammered dulcimer, most flutes, and various keyboard instruments (the virginal, the harpsichord, and clavichord, the last of which evolved into the piano).
"Extensive research" = I googled it.