The Tympani is arguably the best known of the modern percussion instruments. They come in various sizes, construction, and have different types of tuning. In a very general sense, the modern tympani is tuned by means of a series of tuning rods, going through a steel ring held down over the skin. This type of modern tympani has a foot pedal which are connected to the tuning rods with a series of steel rods. The performer presses foot pedal down, and the rods pull down on the tuning rods, tightening the ring and skin, thereby raising the pitch. A skilled tympanist can accurately determine how much pressure he needs to place on the pedal to achieve a defined pitch, and vice versa, can push the rear of the pedal to release the tension, and lower the pitch. Another tuning mechanism on a tympani is a single tuning rod that is connected to all the others by a chain and gears, so when the tympanist rotates the tuning rod, it proportionally changes all the others as the chain moves. The tuning rod is usually equipped with a handle or a place to attach a crank, making the tympanist's job easier.
The modern tympani is normally constructed of copper drums, or kettles, over which a plastic skin is stretched. The performer strikes the skin, with single or multiple strokes, and adds further variation of tone with the use of mallets of varied construction. A hard mallet, with a wooden ball or head brings a sharp tone, where a soft mallet head, often made of cotton or wool give a much softer tone. The user may ascertain from this brief description that the hard mallet produces a much harder attack than the soft mallet, and the composer can exploit this in a variety of instructions to the tympanist, defining which head, and technique is to be used, with a series of notational symbols.
The tympanist usually plays the tympani by striking nearer the edge of the skin than the middle. This allows the tympani to ring, where striking the tympani in the middle produces a much darker sound, but with little or no resonance at all. It's important for the composer to remember that a tympani cannot be retuned immediately. A modern orchestral tympanist has 4 or 5 tympanis to choose from, in varying sizes. Nevertheless, he will still need time to retune a tympani in a performance. A general rule of thumb is when intially tuning or retuning, allow about 15 seconds, and for checking, allow nearer 7 or 8 seconds.
The modern tympanist can play an extreme dynamic range, from the merest whisper to a crashing explosion of sound. He can also play the instruments using a tremolo, or rapid alternating strokes to achieve a sustained tone, which is a common feature of orchestral music written for tympani. There are a number of less used, but still useful additional effects, like rolling a coin across the skin, or placing a bowl on the skin and striking the bowl, whilst varying the tension of the skin with the pedal. This produces an interesting glissando effect not dissimilar to that of a gong or cymbal.
The composer should, and this is relevant for all percussion notation, mark clearly on the tympani part exactly that which he desires from the performer. Do not be afraid to add extensive comments for the performer, including using the header page of the piece to clearly and accurately list the initial tuning, mallet types required, and any additional performance effects and expectations. This is essential for a precise as possible reproduction of the composer's intent