Lingual articulation in songbirds.

Lingual articulation in humans is one of the primary means of vocal tract resonance filtering that produces the characteristic vowel formants of speech. In songbirds, the function of the tongue in song has not been thoroughly examined, although recent research has identified the oropharyngeal-esophageal cavity as a resonance filter that is actively tuned to the frequency of the song. In northern cardinals (Cardinalis cardinalis), the volume of this cavity is inversely proportional to the frequency of the song above 2 kHz. However, cardinal song extends below this range, leaving the question of whether and how the vocal tract is tracking these low frequencies. We investigated the possible role of the tongue in vocal tract filtering using X-ray cineradiography of northern cardinals. Below 2 kHz, there was prominent tongue elevation in which the tip of the tongue was raised until it seemed to touch the palate. These results suggest that tongue elevation lowers the resonance frequency below 2 kHz by reducing the area of the passage from the oral cavity into the beak. This is consistent with a computational model of the songbird vocal tract in which resonance frequencies are actively adjusted by both changing the volume of the oropharyngeal-esophageal cavity and constricting the opening into the beak.

Suthers RA ，Rothgerber JR ，Jensen KK 《-》

Model for vocalization by a bird with distensible vocal cavity and open beak.

Fletcher NH ，Riede T ，Suthers RA 《JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA》

Vocal tract filtering and sound radiation in a songbird.

Nelson BS ，Beckers GJ ，Suthers RA 《JOURNAL OF EXPERIMENTAL BIOLOGY》

Vocal-tract filtering by lingual articulation in a parrot.

Beckers GJ ，Nelson BS ，Suthers RA 《-》

Vocal tract articulation in zebra finches.

Ohms VR ，Snelderwaard PCh ，Ten Cate C ，Beckers GJ ... -  《-》