1. Ukulele: A small, guitar-like instrument with four strings, originating from Hawaii.
2. Upright Bass: Also known as a double bass or contrabass, it is a large stringed instrument that is played standing up or with the musician seated on a high stool.
3. Udu: A West African membranophone, typically made from clay, with a hole at the top and another hole on the side that is covered with a membrane. It produces a distinctive sound when struck with the hands or sticks.
4. Uilleann Pipes: A traditional Irish bagpipe, played with a bellows operated by the elbow and a chanter with keys.
5. Underwater Speaker: A specialized speaker designed for use underwater, emitting sound waves that travel through water instead of air.