▁cas ual ▁observer — b am ! ▁It ' s ▁no ▁coinc idence ▁that ▁he ▁was ▁working ▁at ▁the ▁same ▁time ▁that ▁[ And y ] ▁War hol ▁and ▁[ Ro y ] ▁L ichten stein ▁were ▁doing ▁pop ▁art ." ▁Wilson ▁wrote ▁in ▁ 1 9 9 0 : ▁ ▁Before ▁ 1 9 6 6 , ▁Brian ' s ▁master y ▁of ▁song writing ▁proved ▁that ▁he ▁was ▁capable ▁of ▁applying ▁odd ▁harm onic ▁progress ions , ▁unexpected ▁dis ru ptions ▁of ▁hyper meter , ▁jazz ▁theory , ▁tempo ▁changes , ▁met rical ▁ambigu ity , ▁and ▁unusual ▁tone ▁colors ▁successfully ▁within ▁a ▁pop ▁context . ▁He ▁made ▁on - the - spot ▁dec isions ▁about ▁notes , ▁art ic ulation , ▁and ▁tim bre ; ▁compos ing ▁at ▁the ▁mixing ▁board ▁and ▁using ▁the ▁studio ▁as ▁a ▁musical ▁instrument . ▁Through ▁att ending ▁Phil ▁Spect or ' s ▁sessions ▁sp or ad ically , ▁Brian ▁learned ▁how ▁to ▁act ▁as ▁a ▁producer ▁for ▁records ▁while ▁being ▁educated ▁on ▁the ▁Wall ▁of ▁Sound ▁process . ▁As ▁his ▁produ ctions ▁advanced , ▁he ▁became ▁recognized ▁for ▁his ▁pop ▁art istry , ▁vocal ▁harm on ization , ▁in cess ant ▁studio ▁per fection ism , ▁forward - th inking ▁song ▁structures , ▁engineering ▁and ▁mixing ▁know - how , ▁and ▁cre ative ▁mult it ask ing ▁ab ilities . ▁From ▁then ▁on , ▁Brian ▁received ▁some ▁production ▁advice ▁from ▁Jan ▁Ber ry . ▁As ▁they ▁collabor ated ▁on ▁several ▁hit ▁singles ▁written ▁and