note was necessary to reproduce them correctly. Correct mimicking was performed by singing the first syllable with the appropriate side of the syrinx—right for a high frequency tone and left for low frequency—and the second median tone with the opposite side. When the same side was used for both tones, the step-wise frequency change between the tones became slurred, suggesting that lateralization allows for abrupt frequency changes in song. See also Syrinx (bird anatomy) Bird vocalization Lateralization of brain function Animal communication Bioacoustics References External links X-ray video of a cardinal singing Macaulay Library at the Cornell Lab of Ornithology is the world's largest collection of animal sounds and associated video. xeno-canto a community database with c. 183,000 recordings of c. 9,000 bird species (August 2014) Neuroethology Bird sounds Passeri