norm(data, speakerlabs, type = "gerst", rescale = FALSE)track."nearey", "cen", "lob", "gerst"
(default), for normalisation according to Nearey, centroid method, Lobanov,
or Gerstman."nearey", Nearey : Find the log of each data
element and subtract from each the mean of the logarithmic data.
"cen", centroid: Find the mean of the data column and subtract it
from each data element in that column. "lob", Lobanov: Find the
mean and standard deviation of the data. Subtract the mean from each data
element and devide each result by the standard deviation. "gerst",
Gerstman: Subtract from the data the minimun formant value then devide by
the formant range.