 " Hard " incorporates musical elements of hip hop and is four minutes and ten seconds long . It features militant horns , hissing synths , sharp beats and piano notes . It is written in the key of B minor and set in common time with a pop and R & B groove and a tempo of 91 beats per minute . Rihanna 's vocal range in the song ranges from the low note of G3 to the high note of B4 . As noted by Ailbhe Malone of NME , Rihanna adopts Jay @-@ Z 's vocal style in the lyric , " Brilliant , resilient , fan mail from 27 million . " " Hard " is a song about emulating power and strength , and how Rihanna assumes a role of being the best at what she does . Ryan Dombell of Pitchfork Media wrote that the song is " a strutting statement of power " . 
