Birds have a special organ called the syrinx, that allow them to sing the way they sound. It is located on the trachea to produce sound. It is similar to the mammalian larynx but the way air is used is different. In the syrinx, 100% of the air is converted to sound where the larynx only uses 2%. The vibrated air passes through the syringeal passageway to project on the tympaniform membrane. This vibration is the result of how birds can vocalize. The syrinx is a complex organ itself but the muscle attached around it is also complex. There are layers of muscle structures to create fine adjustment of vibration. The sound produced by the syrinx can be filtered to change the loudness and the pitch. The experiment was done to prove that sound travels faster than helium atmosphere showed sound produced in such atmosphere had different pitch and frequency than the sound produced in our normal atmosphere. The understanding of syrinx and physics of sound helped scientists to learn more about vocalization.