Results of the acoustic analysis.

The age and the sex of each recorded individual, the number of orally and nasally emitted rumbles (and the percentage of those recorded in each context, respectively), and the mean duration, mean fundamental frequency, mean formant frequency values 1 and 2, and mean sound pressure level (SPL) ± SD of rumbles per individual are presented. The estimated vocal tract length (VTL) for each individual based on the spacing in Hz between formants 1 and 2 for nasal and oral rumbles is also given.