meanspec | R Documentation |

This function returns the mean frequency spectrum (i.e. the mean relative amplitude of the frequency distribution) of a time wave. Results can be expressed either in absolute or dB data.

```
meanspec(wave, f, channel = 1, wl = 512, wn = "hanning", ovlp = 0, fftw = FALSE,
norm = TRUE, PSD = FALSE, PMF = FALSE, FUN = mean, correction = "none", dB = NULL,
dBref = NULL, from = NULL, to = NULL, identify = FALSE,
col = "black", cex = 1, plot = 1, flab = "Frequency (kHz)",
alab = "Amplitude", flim = NULL, alim = NULL, type ="l", ...)
```

`wave` |
an R object. |

`f` |
sampling frequency of |

`channel` |
channel of the R object, by default left channel (1). |

`wl` |
length of the window for the analysis (even number of points, by default = 512). |

`wn` |
window name, see |

`ovlp` |
overlap between two successive analysis windows (in %). |

`fftw` |
if |

`norm` |
if |

`PSD` |
if |

`PMF` |
if |

`FUN` |
the function to apply on the rows of the STFT matrix, by
default |

`correction` |
a character vector of length 1 to apply an
amplitude ("amplitude") or an energy ("energy") correction
to the FT window. This argument is useful only when one wish to obtain
absolute values that is when |

`dB` |
a character string specifying the type dB to return: "max0" for a maximum dB value at 0, "A", "B", "C", "D", and "ITU" for common dB weights. |

`dBref` |
a dB reference value when |

`from` |
start mark where to compute the spectrum (in s). |

`to` |
end mark where to compute the spectrum (in s). |

`identify` |
to identify frequency and amplitude values on the plot with the help of a cursor. |

`col` |
colour of the spectrum. |

`cex` |
pitch size. |

`plot` |
if |

`flab` |
title of the frequency axis. |

`alab` |
title of the amplitude axis. |

`flim` |
range of frequency axis (in kHz). |

`alim` |
range of amplitude axis. |

`type` |
if |

`...` |
other |

See examples of `spec`

. This function is based on `fft`

.

If `plot`

is `FALSE`

, `meanspec`

returns a two columns matrix,
the first column corresponding to the frequency axis, the second column
corresponding to the amplitude axis.

If `identify`

is `TRUE`

, `spec`

returns a list with
two elements:

`freq` |
the frequency of the points chosen on the spectrum |

`amp` |
the relative amplitude of the points chosen on the spectrum |

The argument `peaks`

is no more available
(version > 1.5.6). See the function `fpeaks`

for peak(s) detection.

The argument `fftw`

can be used to try to speed up process
time. When set to `TRUE`

, the Fourier transform is computed
through the function `FFT`

of the package `fftw`

. This package is a
wrapper around the fastest Fourier transform of the free C subroutine
library FFTW (http://www.fftw.org/). FFT should be then installed on your OS.

Jerome Sueur sueur@mnhn.fr

`spec`

,`fpeaks`

,
`localpeaks`

, `dynspec`

,
`corspec`

, `diffspec`

, `simspec`

, `fft`

.

```
data(orni)
# compute the mean spectrum of the whole time wave
meanspec(orni,f=22050)
# compute the mean spectrum of a time wave section (from 0.32 s to 0.39 s)
meanspec(orni,f=22050,from=0.32,to=0.39)
# different window lengths
op<-par(mfrow=c(3,1))
meanspec(orni,f=22050,wl=256)
title("wl=256")
meanspec(orni,f=22050,wl=1024)
title("wl=1024")
meanspec(orni,f=22050,wl=4096)
title("wl=4096")
par(op)
# different overlap values (almost no effects here...)
op<-par(mfrow=c(3,1))
meanspec(orni,f=22050)
title("ovlp=0")
meanspec(orni,f=22050,ovlp=50)
title("ovlp=50")
meanspec(orni,f=22050,ovlp=95)
title("ovlp=95")
par(op)
# use of flim to zoom in
op<-par(mfrow=c(2,1))
meanspec(orni,f=22050)
title("zoom in")
meanspec(orni,f=22050,wl=512,flim=c(4,6))
par(op)
# comparaison of spectrum and mean spectrum
op<-par(mfrow=c(2,1))
spec(orni,f=22050)
title("spec()")
meanspec(orni,f=22050)
title("meanspec()")
par(op)
# log scale on frequency axis
meanspec(orni, f=22050, log="x")
# median spectrum
meanspec(orni,f=22050, FUN=median)
# variance spectrum
meanspec(orni,f=22050, FUN=var)
```

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