fickle, volatile -- (marked by erratic changeableness in affections or attachments; "fickle friends"; "a flirt's volatile affections")
erratic, fickle, mercurial, quicksilver -- (liable to sudden unpredictable change; "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next")
(Sound)
