The word comes from the Italian in its preferred spelling. The oldest word of origin is the Greek tympanon (transliterated). So the use of the y (epsilon) is more correct given the Greek origin, BUT since the word is ultimately from the Italian not the Greek the use of the y doesn't work because there is no y in the Italian alphabet (really, there's no w either). So the most correct spelling is TIMPANI.
Now the next question is one of number, the definition tells us timpani is a n. pl. or a plural noun, like sheep. So when we say timpani we mean more than one, and in fact it is extremely rare that only one is used in music. The singular form is timpano, as on my home page under the first graphic, BUT, in actual fact this form is not so often used by timpanists. We tend to say simply drum when we refer to only one instrument, as in "that twenty-nine inch DRUM sounds great" rather than "that twenty-nine inch TIMPANO sounds great".
These days, most timpanists use plastic timpani heads made by Remo, Inc. A number of years ago it was discovered (an effort mainly the responsibility of Cloyd Duff working with the people at Remo) that quality plastic timpani heads have a "grain" in the plastic similar to that of a natural calfskin head, and that if the head is both manufactured and mounted with attention paid to the placement of the grain, better and more consistent quality control and a superior sound is achieved.
At first the grain line was marked on the outside edge of the head with a marking pen; eventually Remo began to manufacture their heads with the more permanent marking as you can see here in the graphic. There is some debate among timpanists as to whether the presence of the line marking itself has a negative effect on the sound. My opinion is that its effect is at best insignificant.
Those "little brown things" sometimes placed on top of the timpani are called mutes. They can be made of various materials but leather is probably used most often. These pads are quite inexpensive to procure. Timpanists can often be found in Army/Navy surplus stores, or in suede shops like Tandy Leather, asking for the bin of leather scraps. We look for pieces large enough to cut into squares of about eight to ten inches, and then fold them over a couple of times to make them compact.
The pads, or mutes, serve a twofold purpose. The first is cancellation of any sympathetic vibrations that any drums (which are not being used during a particular piece or movement) can pick up from other drums actually in use. Simply placing the pad on top of the head in the correct location easily facilitates this type of muffling. This is important because the timpani are highly resonant instruments. Timpanists often place their hands onto one drum almost immediately after striking it so that the vibrations do not "bleed-over" and obscure the sound of another drum about to be played. These sympathetic vibrations cloud not only the attack, but also the clarity of the ringing pitch of the next drum to be struck. With this in mind, one can see how useful the mutes are when they completely silence a drum that is not being played at all.
The second purpose of a mute is to "dry out" the tone of a drum while it IS being played. Sometimes a composer writes a musical passage requiring a sound that is much less resonant than the timpani can possibly produce under normal playing conditions. Usually a harder mallet (one with less felt sewn around the playing end of the stick) is sufficient to produce a sound that can be described as mostly attack (or "impact" or "point") with very little resonant tone following it. Sometimes, however, the required sound is so dry that it cannot be produced without the assistance of a mute -- regardless of how hard a mallet is used -- and this is accomplished by placing the pad on the drum (or on several timpani if needed). A most interesting aspect of this placement of the pad is that, owing to how vibrations traverse across the head of the drum, different degrees of dryness can be attained by placing the mute at different locations around the head. If put directly over the center of the drum, a minimum amount of dryness occurs. If moved six to eight inches in almost ANY direction from the center, maximum dryness is attained. Finally, placing a pad over the edge of the drum, just barely in from the "lip" of the bowl will produce a moderate degree of dryness, or "muting" (ergo the name).
Probably for the same reason that maintenance men always seem to carry a large chain of keys hooked to their belt straps or mechanics have toolboxes that fill up an entire wall. Our sticks, or mallets, could be considered the timpanist's "keys" for entrance into various doorways of sound possibilities. There exists a veritable plethora of various types of sounds and tones available (MUCH more than just a simple BOOM), and the timpanist must to be able to vary his or her tone quality to blend with the myriad of sound possibilities of the full symphony orchestra. This is done by use of a wide range of different pairs of mallets, all of unique construction. In addition, there are numerous ways to hold or grip the sticks, as well as various ways to strike the timpani with them, but that subject should be treated separately.
The first aspect of mallet construction is the shaft itself. A number of different woods are commonly used by timpanists and mallet makers. Various qualities of the wood are important to consider such as weight, density, strength, flexibility, warp-ability, length of grain and so on. Probably the most obvious important characteristic is the weight of the wood. All musicians have the ability to brighten or darken the tones produced by their instrument, which is necessary to fit the different moods of the music being performed. For the timpanist, the weight of the mallet is a very important consideration in producing a tone that is bright, dark, or somewhere in between. Basically, the heavier the wood -- the darker the tone. Some of the various woods commonly used by timpanists (in order from light to heavy) are: bamboo, cherry, birch, maple, and hickory. Most professional timpanists utilize several of these woods in their standard set of sticks in order to blend with different sounds going on around them in a performance.
Another facet of stick construction is the felt, which makes direct contact with the drum head. The timpanist also needs to vary his or her sound in terms of the amount of resonance produced by the drum(s). An extremely resonant tone is often called a fat (or broad) sound. The opposite of this, where one hears mostly the attack with little resonance, is labeled dry (or pointed). To achieve this, various types, as well as amounts, of felt are sewn onto the stick. Basically, the more felt on a stick -- up to a point, anyway -- the fatter the sound. In addition, the type of felt used has an impact (pardon the pun), on the amount of resonance produced. We buy damper felt as used by piano technicians, and these felts have a certain range of tightness to their weave as well as a range of materials used by the felt manufacturer. At its simplest, the tighter the weave -- the dryer (or more pointed) the sound.
Finally, there is a small hard "core" glued onto the end of the mallet which the felt is sewed around, which also contributes to this quality of sound "shape" I've been talking about. Materials often used for this core (from softest to hardest) are: cork, hard piano damper felt, and wood, or combinations of these. There is the same relationship berween the hardness of the core and the resulting sound quality -- the harder the core, the dryer (or more pointed) the sound.
In summary, the types of sound discussed here -- bright, dark, fat, pointed -- seem to indicate qualities more associated with vision (color and shape) rather than hearing. Yet these terms are well known to, and often used by, all instrumentalists in discussing the subject of orchestral sound. Therefore, in order for the professional timpanist to manipulate the sound of the drum in order to blend and play "in context" with both the orchestra and the music, he or she MUST have a large arsenal of sticks in the case, ready to "roll".
No, we are not doubled over in pain. We are, in fact, tuning our timpani. If you've ever had a good look at our drums up close (or from a balcony) you may have noticed that each timpano has a foot pedal about twelve inches or so from the floor. This pedal allows the timpanist to change the pitch of the drum. This may be somewhat confusing because not all percussion instruments produce actual pitches (many simply seem to go "BOOM" to the average listener), and of those that can, VERY few have the ability to actually change those pitches. But I need to back up a bit. Percussion instruments are grouped into two categories: indefinitely pitched and definitely pitched. The indefinitely pitched instruments include the snare drum, bass drum, cymbals, triangle, tom-toms, tambourine, and a host of others. When struck, they emit a band of frequencies that is too wide and scattered for the human ear to discern actual pitches from them. Some of the definitely pitched percussion instruments include the xylophone, marimba, bells (or glockenspiel), chimes and the timpani. These instruments are crafted so that the band of vibrations emitted is much narrower when struck, allowing the human ear and brain to perceive a discernible pitch. Of these specific instruments mentioned above, only the timpani can actually VARY their pitches, and the foot pedal is the mechanism that the timpanist manipulates to do so. I could go into a very detailed explanation of how all this works, but that would entail quite a lot of technical talk. Suffice it to say that when the timpanist pushes the pedal down, it stretches the timpani head and drives up the pitch in the same way that stretching a rubberband while plucking it also produces a pitch that is consistently higher.
Timpanists need to be able to tune and re-tune their drums because music is written in various keys. When the key changes -- between compositions, in pauses between movements, possibly even in the middle of a piece -- the timpanist must re-tune to remain in "harmonic-sync" with the orchestra. It's either that or "stick out like a sore thumb".) So when you see us bending over the drum a lot, we are quietly and discreetly tapping our fingers or mallets on the drum head to check our new notes.
Actually, it's none of the above. Though there are clues to the reason hidden in the last two sillier answers. Basically, we're just fine-tuning our instruments. Brass players tune by manipulating slides, woodwinds by adjusting lengths of joints between sections of their instruments, and strings have the tuning pegs or the fine-tuners on the tailpiece. We do it by manipulating ("fiddling with") the tension placed on each instrument's drumhead.
If you've watched your local timpanist do this prior to, and sometimes during a performance, you may have noticed a long metal rod on the outside of the kettle, extending downward from wherever the performer places his T-handle ("screw-thingie"). There are normally eight of these long rods extending around the drum, and together they serve as the principal means of fine-tuning the timpani. At the top end they are connected to a round metal collar (or counterhoop) which is placed over the drumhead and holds it in place. These rods are then connected at the bottom of the drum to what we call the "spider mechanism" (spider because of the eight rods connected to it, and its resulting appearance of having as many legs). This spider mechanism moves down when the timpanist pushes his foot pedal down to raise the pitch, and vice versa. The downward movement of the spider also pulls the rods downward which also pulls down the counterhoop at the top of the drum, which drives up the pitch because of the increased tension.
But I'm getting ahead of myself. These eight rods are actually long screws, with a few inches of threading at the bottom, and they connect to the spider mechanism in such a way that we can actually "fine-tune" the timpani. For our instrument to produce a clear ringing pitch when struck, it must be played in tune with itself. To accomplish this, the tension applied to the head must be equal at all eight points around the drum. By placing (and then manipulating) the hand-held T-handle on top of the long threaded rod, the timpanist can make fine adjustments to the tension at each of the eight connecting points. This is done by striking the drum lightly in front of the rod, listening for the pitch and then tightening or loosening the rod accordingly. This is a very complex skill to master on timpani. It takes years of practice to develop one's ears so one can really hear the minute pitch discrepancies in a localized part of the drum, especially in the context of the resonance of the entire head. One's constant goal is an absolutely clear pitch sounding from the entire ringing surface of the drum head. It's the only way to play in tune, and a basic ingredient to producing a beautiful musical tone on the instrument.
Have you ever attended a concert in which the timpanist's contribution seemed to amount to nothing more than glorifed noise? That can, frankly, be due to a number of factors and a common cause is the performer's inability to fine-tune the instrument. If, on the other hand, you've heard a concert in which you were struck by the beauty of the timpani sound, then I guarantee you -- he or she was playing in tune. There were probably ten or twenty other things that the timpanist was doing right as well, but added together they wouldn't have accounted for nearly as much when the timpani are out of tune, either with themselves or with the orchestra.