Um and ah
Both ‘um and ah’, which is more British, and ‘hem and haw’, which is more American, are expressions of hesitancy when dithering to find the right words when communicating with others. Both expressions are echoic or imitative of the sounds one makes in clearing one’s throat or thinking of the right words to say. Hem is similar to ahem and dates from the 15th century, while haw dates from the 1600s. In Shakespeare’s time, the expression was ‘hum and ha’ as in Merry Wives of Windsor Act III, Scene V, “Hum! Ha! Is this a vision? Is this a dream?” ‘Um and ah’ is first cited as an expression from the late 1600s, while ‘hem and haw’, the American version, comes a little later during the 1700s.