# Synthesis of time wave (tonal model) This functions synthesizes pure tone sound based on an amplitude envelope and an instantaneous frequency contour. The function can also be used to modify a reference sound. ```r synth2(env = NULL, ifreq, f, plot = FALSE, listen = FALSE, output = "matrix", ...) ``` ## Arguments - `env`: a numeric vector describing the amplitude envelope (i.e. the amplitude modulation). By default `NULL`, generating a squared enveloppe. - `ifreq`: a numeric vector describing the instantaneous frequency (in Hz). - `f`: a numeric vector for the sampling frequency (in Hz) - `plot`: if `TRUE` returns the spectrogram of the synthezised sound (by default `FALSE`). - `listen`: if `TRUE` the new sound is played back. - `output`: character string, the class of the object to return, either `"matrix"`, `"Wave"`, `"Sample"`, `"audioSample"` or `"ts"`. - ``...``: other `spectro` graphical parameters. ## Details `env` and `ifreq` must have exactly the same length. The amplitude envelope can be obtained with the Hilbert envelope (function `env`) and the instantaneous frequency can be obtained with the Hilbert transform (function `ifreq`). This opens a great variety of signal modidications as shown in the example section. ## Returns If `plot` is `FALSE`, a new wave is returned. The class of the returned object is set with the argument `output`. ## References Beeman, K. 1998 Digital signal analysis, editing and synthesis, in **Animal acoustic communication** edited by Hopp SL, Owren MJ, Evans CS, Springer, 59-103. ## Author(s) Jérôme Sueur and Laurent Lellouch ## See Also `synth2`, `noisew`, `pulse`, `echo` ## Examples ```r ## You can use plot=TRUE and spectro() options ## to directly 'see' the new-built sounds ## MODIFICATION OF A REFERENCE SIGNAL data(tico) env.tico <- env(tico, f=22050, plot=FALSE) ifreq.tico <- ifreq(tico, f=22050, plot=FALSE)$f[,2] # recover the original signal s <- synth2(env=env.tico, ifreq=ifreq.tico*1000, f=22050) # original signal with instantaneous frequency reversed s <- synth2(env=env.tico, ifreq=rev(ifreq.tico)*1000, f=22050) # original signal with a +1000 Hz linear frequency shift s <- synth2(env=env.tico, ifreq=ifreq.tico*1000+1000, f=22050) # original signal with instantaneous frequency multiplied by 2 s <- synth2(env=env.tico, ifreq=ifreq.tico*1000*2, f=22050) # original signal with a linear instantaneous frequency at 2000 Hz s <- synth2(env=env.tico, ifreq=rep(2000, times=length(tico@left)), f=22050) ## DE NOVO SYNTHESIS # instantaneous frequency increasing by step of 500 Hz s <- synth2(ifreq=rep(c(500,1000,1500,2000,2500,3000,3500,4000), each=2000), f=16000) # square function of the instantaenous frequency s <- synth2(ifreq=500+seq(-50,50, length.out=8000)^2, f=8000) # linear increase of the amplitude envelope s <- synth2(env=seq(0,1,length=8000), ifreq=rep(2000,8000), f=8000) # square-root increase of the amplitude envelope s <- synth2(env=sqrt(seq(0,1,length=8000)), ifreq=rep(2000,8000), f=8000) # square-root increase and decrease of the amplitude envelope s <- synth2(env=c(sqrt(seq(0,1,length=4000)), sqrt(seq(1,0,length=4000))), ifreq=rep(2000,8000), f=8000) # amplitude envelope and instantaneous frequency following a normal density shape norm <- rep(dnorm(-4000:3999, sd=1000), 2) s <- synth2(env=norm, ifreq=500+(norm/max(norm))*1000, f=8000) ```

synth2 function