# plotVowels.R
# Script for plotting vowel formants in a hertz space and then 
# in an ERB space, making the x- and y-axes cover the same range.

# Start by setting the working directory to the directory where 
# you have the txt file containing the vowel formant values that
# you want to plot (and where you want to store the output pictures.
# Change the path name as below.  
setwd('c:/Lx600.01')

# Read in the data as a data frame.  This assumes that you have 
# a file with three tab-separated columns, that looks something
# like this, which is the contents of the sampleVowels.txt file
# that is linked into the course web page.  Change the file name 
# as appropriate.
#
# vowel	F1_Hz	F2_Hz
# [i]	360	2400
# [e]	680	1900
# [a]	800	1300
# [o]	590	900
# [u]	390	900
formants=data.frame(read.table("sampleVowels.txt",header=TRUE,sep="\t"))

# Make two new columns that are the ERB values for these formants, 
# and name them appropriately.  The formula for calculating ERB here 
# is taken from the following locus classicus:
#   Moore, B., & Glasberg, B.R. (1987). "Formulae describing frequency
#   selectivity as a function of frequency and level, and their use 
#   in calculating excitation patterns." Hearing Research, 28, 209-225.
# ERB stands for "equivalent rectangular bandwidth" and is a slightly 
# modified timbre scale that is close to Barks, differing mostly in 
# low frequencies.  
formants$F1_ERB=
	11.17*log(((formants$F1_Hz/1000)+0.312)/((formants$F1_Hz/1000)+14.675))+43
formants$F2_ERB=
	11.17*log(((formants$F2_Hz/1000)+0.312)/((formants$F2_Hz/1000)+14.675))+43

# Set up a window that is 6" wide by 6" high, using 12point type.
windows(w=6,h=6,pointsize=12)
# Specify plotting parameters to make the font be a serif font and 
# make the plot be square, and have no outside margin around the plot.
par(family="serif",pty="s",oma=rep(0,4))

# Plot the formants in hertz space, with the x-axis going from 
# 2500 to 900 and the y-axis going from 1400 to 0.
plot(formants$F2_Hz,formants$F1_Hz,xlim=c(2500,900),ylim=c(1500,0),
	xlab="second formant measured at vowel mid point (Hz)",
	ylab="first formant measured at vowel mid point (Hz)",pch=19)
# Add text to label the points.
text(formants$F2_Hz,formants$F1_Hz,formants$vowel,adj=c(1.5,0))

# Save the plot to a file of type "wmf" (for Windows Metafile).  
# Specify "ps" if you want to a Postscript file, "pdf" if you 
# want a PDF file, and so on.  Type help(savePlot) to get more 
# options and to understand the syntax of this command.
savePlot("formantsHz",type="wmf")

# Now plot the formants in ERB 
# space, with the x-axis going from 
# 23 to 14 and the y-axis going from 15 to 6.
plot(formants$F2_ERB,formants$F1_ERB,xlim=c(23,14),ylim=c(15,6),
	xlab="second formant measured at vowel mid point (ERB)",
	ylab="first formant measured at vowel mid point (ERB)",pch=19)
# Add text to label the points.
text(formants$F2_ERB,formants$F1_ERB,formants$vowel,adj=c(1.5,0))

# Save the plot to a file of type "wmf" (for Windows Metafile).  
# Specify "ps" if you want to a Postscript file, "pdf" if you 
# want a PDF file, and so on.  Type help(savePlot) to get more 
# options and to understand the syntax of this command.
savePlot("formantsERB",type="wmf")