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ukulele - a small four stringed guitar originally from Portugal, most associated with Hawaiian songs. There are several different tunings. Standard tuning is G(fourth string ), C (third string ), E (second string )and A (first string). There are four main sizes, soprano (standard), concert, tenor and baritone.
unison - playing or singing the same notes together with another instrument or voice.
upbeat - or up-tempo, music played fast and lively.
undertones - much theorizing has been done on this topic. The most popular explanation seems to be one of two. One being that each instrument has particular sounds produced by the vibration of differing materials creating an overall sound beyond the basic or harmonic note that is played. The other is a theoretical interpretation of harmony and emotion in the descending minor triad.
