Table 1.

Vocal changes following lesion surgery to the alar edge of the ventral pouch. Animals were recorded before surgery and twice (immediately and two weeks) after surgery. The table lists qualitative differences between the spectrographic appearance of USV observed before and after surgery. None of the animals showed signs of respiratory stress. The table also lists the results of the evaluation of the magnitude of the lesion to the ventral pouch (reconstructed laryngeal airway). After the second sound recording (two weeks after surgery), animals were sacrificed. The dissected larynx was fixed and imaged with contrast-enhanced microCT. USV, ultrasonic vocalization.

ratvocal changereconstructed laryngeal airwaydiagnosis
alar rat 1, male
  • Immediately after surgery: complete loss of USVs after surgery

  • Two weeks after surgery: USVs reminiscent of 50 and 22 kHz calls indicate that sounds occupy normal frequency ranges, but duration and characteristic frequency modulation patterns are different. The rat produces a lot of sniffing when excited by female bedding. Sniffs are sometimes associated with ultrasonic components

  • Alar cartilage is broken

  • Alar edge is discontinuous, right portion is missing

  • Mucosa of ventral pouch is normal

Severe vocal change associated with damage to the ventral pouch
alar rat 2, male
  • Immediately after surgery: rat produces modified USV. 50 and 22 kHz calls contain sidebands and sound amplitude is reduced

  • Two weeks after surgery: 50 kHz calls can be recognized, but fundamental frequencies are lower than prior to surgery. 22 kHz calls are shorter than before surgery

  • Alar cartilage is not broken

  • Alar edge is intact

  • Mucosa of ventral pouch is thickened

Mild vocal change associated with minor alteration of the mucosa inside an intact ventral pouch
alar rat 3, male
  • Immediately after surgery: complete loss of USVs after surgery. The rat produces sniffs when excited by female bedding, which are associated with ultrasonic components

  • Two weeks after surgery: only very short or incomplete 22 kHz calls produced, but the animal shows typical slow breathing motions associated with long 22 kHz call production. No 50 kHz calls are produced, although the animal is stimulated when exposed to female bedding

  • Alar cartilage is broken

  • Alar edge is partly removed

  • Mucosa of ventral pouch is thickened

Severe vocal change associated with damage to ventral pouch
alar rat 4, male
  • Immediately after surgery: rat produces normal USVs

  • Two weeks after surgery: rat produces normal USVs

  • Alar cartilage is intact

  • Alar edge is continuous

  • Mucosa of ventral pouch is thickened

No vocal change associated with minor alteration of the mucosa inside the ventral pouch
alar rat 5, female
  • Immediately after surgery: complete loss of USVs after surgery

  • Two weeks after surgery: modified 50 kHz calls, no 22 kHz calls but typical slow breathing motions associated with long 22 kHz call production

  • Alar cartilage is broken and alar edge is level with the surface of epiglottis

  • Mucosa of ventral pouch is thickened

Severe vocal change associated with damage to ventral pouch
alar rat 6, female
  • Immediately after surgery: complete loss of USVs

  • Two weeks after surgery: no USV. Sniffs sometimes contain USV components

  • Alar cartilage is broken

  • Alar edge is removed

  • Mucosa of ventral pouch is thickened

Severe vocal change associated with damage to ventral pouch