seewave (version 1.6.4)

corenv: Cross-correlation between two time wave envelopes

Description

This function tests the similarity between two time wave envelopes by returning their maximal correlation and the time shift related to it.

Usage

corenv(wave1, wave2, f, envt="hil", msmooth = NULL, ksmooth = NULL,
plot = TRUE, plotval = TRUE,
method = "spearman", col = "black", colval = "red",
cexval = 1, fontval = 1, xlab = "Time (s)",
ylab = "Coefficient of correlation (r)", type = "l", pb = FALSE, ...)

Value

• If plot is FALSE, corenv returns a list containing four components:
• r
  a two-column matrix, the first colum corresponding to the time shift (frequency x-axis) and the second column corresponding to the successive r correlation values between env1 and env2 (correlation y-axis).
• rmax
  the maximum correlation value between x and y.
• p
  the p value corresponding to rmax.
• t
  the time offset corresponding to rmax.

Details

Successive correlations between the envelopes of wave1 and wave2 are computed when regularly sliding forward and backward wave2 along wave1. The maximal correlation is obtained at a particular shift (time offset). This shift may be positive or negative. The higher smooth is set up, the faster will be the computation but less precise the results will be. The corresponding p value, obtained with cor.test, is plotted. Inverting wave1 and wave2 may give slight different results.

See Also

env,corspec,covspectro, cor,cor.test.

Examples

data(orni)
# cross-correlation between two echemes of a cicada song
wave1<-cutw(orni,f=22050,from=0.3,to=0.4,plot=FALSE)
wave2<-cutw(orni,f=22050,from=0.58,to=0.68,plot=FALSE)
corenv(wave1,wave2,f=22050)