Musical instruments that start with the letter I include the igil, ipu, Irish uillean, Irish bouzouki, ichigenkin, inci, iya, itotele and istarski mih. The instruments originate from countries ranging from Cuba and Ireland to Croatia, Japan and the Philippines.
Bessel's functions are often used in acoustics for describing circular membranes behaviour (exploited by most of the musical instruments). They are the solutions of the wave equations using polar coordinates. Set the properties of the membrane Bessel's functions describe the vibrational modes of the membrane.
A bezel is a narrow piece of metal used to hold a gem in place on a piece of jewelry. The bezel surrounds the gemstone all the way around. A bezel is also the part of the watch surrounding the crystal on a watch face that holds the crystal in place. Bezels may or may not be set with gems and may or may not be textured.