A polymer interlayer comprising: a first layer comprising a first poly(vinyl butyral) resin having a first residual hydroxyl content of from 8 to 14 weight percent and a first residual acetate content, and a first plasticizer, wherein the first plasticizer comprises an aromatic moiety, and the plasticizer content is less than 100 phr and greater than 10 phr; and a second layer comprising a second poly(vinyl butyral) resin having a second residual hydroxyl content and a second residual acetate content, and a second plasticizer; wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 4.0 weight percent; wherein the residual hydroxyl contents, the residual acetate contents and the plasticizers are selected such that the polymer interlayer has at least one glass transition temperature less than 20°C and a peak tan delta of greater than 1.33, wherein the glass transition temperature is determined by dynamical mechanical thermal analysis (DMTA) in shear mode, which measures the storage (elastic) modulus (G') in Pascals, loss (viscous) modulus (G") in Pascals, tan delta (=G"/G') of the specimen as a function of temperature at a frequency of 1 Hz and temperature sweep rate of 3°C/min, the glass transition temperature then being determined by the position of the tan delta peak on the temperature scale in °C, and a glass panel having a configuration of 2.3-mm glass//interlayer//2.3-mm glass and at 20°C has a transmission loss, TL w, of greater than 42 decibels as measured by weighted average sound transmission loss at 2000 to 8000 Hz, and a transmission loss, TL c, of greater than 38 decibels at the coincident frequency, the sound transmission loss being determined with ASTM E90. a first layer comprising a first poly(vinyl butyral) resin having a first residual hydroxyl content of from 8 to 14 weight percent and a first residual acetate content, and a first plasticizer, wherein the first plasticizer comprises an aromatic moiety, and the plasticizer content is less than 100 phr and greater than 10 phr; and a second layer comprising a second poly(vinyl butyral) resin having a second residual hydroxyl content and a second residual acetate content, and a second plasticizer; wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 4.0 weight percent; wherein the residual hydroxyl contents, the residual acetate contents and the plasticizers are selected such that the polymer interlayer has at least one glass transition temperature less than 20°C and a peak tan delta of greater than 1.33, wherein the glass transition temperature is determined by dynamical mechanical thermal analysis (DMTA) in shear mode, which measures the storage (elastic) modulus (G') in Pascals, loss (viscous) modulus (G") in Pascals, tan delta (=G"/G') of the specimen as a function of temperature at a frequency of 1 Hz and temperature sweep rate of 3°C/min, the glass transition temperature then being determined by the position of the tan delta peak on the temperature scale in °C, and a glass panel having a configuration of 2.3-mm glass//interlayer//2.3-mm glass and at 20°C has a transmission loss, TL w, of greater than 42 decibels as measured by weighted average sound transmission loss at 2000 to 8000 Hz, and a transmission loss, TL c, of greater than 38 decibels at the coincident frequency, the sound transmission loss being determined with ASTM E90.