Calculate locus equations for two-dimensional data
The function plots a locus equation and returns associated statistical information.
locus( target, onset, labels.vow = NULL, yxline = TRUE, plotgraph = TRUE, axes = TRUE, ... )
target |
a numerical vector typically of F2 values at the vowel target |
onset |
a numerical vector typically of the same length as target of F2 values at the vowel onset |
labels.vow |
an optionally character vector for plotting labels at the points (target, onset) of the same length as target |
yxline |
optionally plot the line target = onset. Defaults to True. |
plotgraph |
a logical vector for specifying whether the data should be plotted. Defaults to True. |
axes |
A logical vector indicating whether the axes should be plotted |
... |
graphical options par |
A locus equation is a straight line regression fitted with lm() in which the F2- values typically at the vowel onset are regressed on those of the target. The slope can be used to give an indication of target-on-onset coarticulatory influences.
The best estimate of the locus frequency is where the locus equation bisects the line target = onset.
A list containing regression diagnostics of the function lm() that can be accessed with summary() and the estimated locus frequency in \$locus. A plot of values in the onset x target plane with superimposed locus equation and line onset=target.
Jonathan Harrington
# calculate an F2-locus equation for initial [d] # preceding lax vowels produced by female speaker "68". # the onset is taken at the vowel onset; the # vowel target is taken at the vowel's temporal midpoint. # identify initial "d" of speaker "68" temp <- vowlax.left == "d" & vowlax.spkr == "68" # get the F2 value at the vowel's temporal midpoint targ <- dcut(vowlax.fdat[temp,2], .5, prop=TRUE) # F2 value at the vowel's acoustic onset. on <- dcut(vowlax.fdat[temp,2], 0, prop=TRUE) # locus equation plot result <- locus(targ, on, vowlax.l[temp]) # statistical diagnostics of the regression line (locus equation) summary(result) # intercept and slope result$coeff # best estimate of the locus frequency, i.e. the # point of bisection of on = TRUEarg with the regression line result$locus
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.