Calculate vocal tract length

This command displays in the Info window the estimated vocal tract length in the neutral configuration, calculated from a formant frequency value.


Adapted from the procedure described at:
http://www.languagebits.com/phonetics-english/resonant-frequencies-and-vocal-tract-length/

Code in R by Romeo Mlinar:
http://www.languagebits.com/files/formants-tract-length-in-r.html

Original formula from Johnson, Keith. Acoustic and Auditory Phonetics. 2nd ed. Malden, Mass: Blackwell Pub, 2003. p. 96