# modification of a signal with the synthesis function synth2()
data(tico)
env.tico <- env(tico, f=22050, plot=FALSE)
ifreq.tico <- ifreq(tico, f=22050, plot=FALSE)$f[,2]
# original signal with instantaneous frequency reversed
synth2(env=env.tico, ifreq=rev(ifreq.tico)*1000, f=22050, plot=TRUE)