Duan H, et al. - In this population-based twin study, researchers evaluated the heritability of better ear hearing level (BEHL), defined as hearing level of the better ear at a given frequency, and pure-tone averages at the middle (0.5, 1.0, and 2.0 kHz) and high (4.0, 8.0, and 12.5 kHz) frequencies among middle-aged and elderly Chinese twins. In addition, they sought for their genetic correlations. Analyzing 226 monozygotic and 132 dizygotic twin-pairs and 1 triplet (age range, 33 to 80 years; mean age, 51.55 years), they identified a reverse J-shaped pattern of BEHLs at six frequencies by age and sex. As per the univariate analysis, at the frequencies between 2.0 and 12.5 kHz, the heritability of BEHLs ranged from 47.08 to 54.20%, but at the frequencies of 0.5 and 1.0 kHz, the heritability was 1.65% and 18.68%, respectively. At the middle and high frequencies, the heritability of pure-tone average was 34.77% and 43.26%, respectively. They identified significant genetic correlations among BEHLs at all six frequencies in multivariate analysis, with the correlation coefficients ranging from 0.48 to 0.83 at middle frequencies, and from 0.46 to 0.75 at high frequencies.