– ▁management ▁coord ination ▁Justin ▁Sie gel   – ▁production ▁coord ination ▁Mich elle ▁Thomas   – ▁artist ▁development ▁Dave ▁Tom ber lin   – ▁public ist ▁Thom ▁Pan un z io   – ▁A & R Per form ers N icole ▁Sch er z inger   – ▁lead ▁vocals , ▁background ▁vocals ▁Car mit ▁Bach ar   – ▁vocals , ▁backing ▁vocals ▁Mel ody ▁Thor nt on   – ▁vocals , ▁backing ▁vocals ▁Ash ley ▁Roberts ▁  – ▁background ▁vocals ▁ ▁Jess ica ▁S ut ta ▁  – ▁background ▁vocals ▁Kim ber ly ▁Wy att   – ▁background ▁vocals ▁B usta ▁Rh ym es   – ▁featuring ▁artist , ▁vocals , ▁co - writer ▁( track ▁ 1 ) ▁will . i . am   – ▁featuring ▁artist , ▁vocals , ▁co - writer ▁( track ▁ 2 ) ▁Tim bal and   – ▁featuring ▁artist , ▁vocals ▁( track ▁ 3 ) ▁K ara ▁D io Gu ardi   – ▁additional ▁background ▁vocals ▁( track ▁ 1 4 ) ▁K aya ▁Jones   – ▁additional ▁background ▁vocals ▁( tra cks ▁ 1 3 ▁& ▁ 1 5 ) The ▁P CD ▁Orchestra V i ol ins   – ▁End re ▁Gran at , ▁Natal ie ▁Leg get t , ▁Bruce ▁D uk ov , ▁Jack ie ▁Brand , ▁Charlie ▁B ish ar at , ▁Jo el ▁Der ou in , ▁S ara ▁Park ins , ▁Mario ▁De le on , ▁Josef ina ▁Ver g ara , ▁Tam my ▁Hat wan ,