This paper measures the efficiency as Shannon information calculated on a Google corpus correlated against word length: https://www.pnas.org/content/108/9/3526

This paper measures the efficiency as Shannon information calculated on a Google corpus correlated against word length: https://www.pnas.org/content/108/9/3526 https://www.pnas.org/content/108/9/3526 This paper shows that speaker size correlates close to .9 with efficiency: https://royalsocietypublishing.org/doi/10.1098/rstb.2015.0192 https://royalsocietypublishing.org/doi/10.1098/rstb.2015.019...