Santiago Barreda
Postdoctoral Researcher, Dept. of Physiology, University of Arizona

Main Research Vignettes CV phonTools Statistics Links

 


normalize [phonTools]


This function normalizes vowel data using several different methods in order to facilitate the comparison of vowels produced by different speakers. The figures show normalized vowels from the Peterson & Barney data, plotted using the vowelplot() function included on this package. The methods currently supported are Nearey intrinsic (NeareyI) and extrinsic (NeareyE) log-mean normalization, Lobanov and Watt and Fabricius (wandf). Normalizing vowel data can greatly reduce between-category overlap relative to raw formant-data.

 

 

Code used to generate examples:


library (phonTools) ## normalize all Peterson & Barney (1952) vowels using each method. data (pb52) neareyE = normalize (pb52[,7:9], pb52$speaker, pb52$vowel, method = 'neareyE') lobanov = normalize (pb52[,7:9], pb52$speaker, pb52$vowel, method = 'lobanov') wandf = normalize (pb52[,7:9], pb52$speaker, pb52$vowel, method = 'wandf', corners = c('i','A')) ## compare normalization methods using vowelplot(). par (mfrow = c(2,2), mar = c(4,4,3,1)) vowelplot (pb52[,7], pb52[,8], pb52$vowel, alternateAxes = TRUE, pointType = 16, main = 'Raw data', ellipses = TRUE, logaxes = 'xy') vowelplot (neareyI[,1], neareyI[,2], neareyI$vowel, alternateAxes = TRUE, pointType = 16, main = 'neareyI', ellipses = TRUE) vowelplot (lobanov[,1], lobanov[,2], lobanov$vowel, alternateAxes = TRUE, pointType = 16, main = 'lobanov', ellipses = TRUE) vowelplot (wandf[,1], wandf[,2], wandf$vowel, alternateAxes = TRUE, pointType = 16, main = 'wandf', ellipses = TRUE)