acoustat | R Documentation |

This function returns statistics based on STFT time and frequency contours.

```
acoustat(wave, f, channel = 1, wl = 512, ovlp = 0, wn = "hanning",
tlim = NULL, flim = NULL,
aggregate = sum, fraction = 90,
plot = TRUE, type = "l", ...)
```

`wave` |
an R object. |

`f` |
sampling frequency of |

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

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

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

`wn` |
window name, see |

`tlim` |
modifications of the time limits of the analysis (in s). |

`flim` |
modifications of the frequency limits of the analysis (in kHz). |

`aggregate` |
a character vector of length 1 specifying the function to be applied on the rows (time) and columns (frequency) of the STFT matrix. By default set to |

`fraction` |
a numeric vector of length 1, specifying a particular fraction of the contours amplitude to be captured by the initial and terminal percentile values (in %). See details. |

`plot` |
a logical, if |

`type` |
if |

`...` |
other |

The principle of `acoustat`

is as follows:

Compute the short-term Fourier transform (STFT) with usual parameters (

`wl`

for window length,`ovlp`

for overlap of successive windows, and`wn`

for the name of window shape).This results in a time * frequency matrix.

Compute an aggregation function (specified with the argument

`aggregate`

set by default to`sum`

) accross rows and columns of time * frequency matrix.)This results in two components: (

*i*) the time contour, and (*ii*) the frequency contour.Each contour is considered as a probability mass function (PMF) and transformed into a cumulated distribution function (CDF).

Measures are extracted from each CDF: median (M), initial percentile (P1) value, terminal percentile (P2) value, interpercentile range (IPR). P1, P2 and IPR are defined using a fraction parameter (

`fraction`

) that sets the percent of the contour amplitude to be captured by the initial and terminal percentile values. A fraction of 50% would result in the familiar quartiles and interquartile range. An energy fraction of 80% would return the 10th and 90th percentile values, and the width of the range in between.

The function returns a list with 10 items:

`time.contour` |
the time contour as a two-column matrix, the first colum being time (s) and the second colum being the amplitude probability mass function (no scale). |

`freq.contour` |
the frequency contour as a two-column matrix, the first colum being frequency (kHz) and the second colum being the amplitude probability mass function (no scale). |

`time.P1` |
the time initial percentile |

`time.M` |
the time median |

`time.P2` |
the time terminal percentile |

`time.IPR` |
the time interpercentile range |

`freq.P1` |
the frequency initial percentile |

`freq.M` |
the frequency median |

`freq.P2` |
the frequency terminal percentile |

`freq.IPR` |
the frequency interpercentile range |

`acoustat`

was originally developped in Matlab language by Kurt Fristrup and XXXX Watkins (1992) .

The R function was kindly checked by Kurt Fristrup.

Jerome Sueur

Fristrup, K. M. and Watkins, W. A. 1992. Characterizing acoustic features of marine animal sounds. Woods Hole Oceanographic Institution Technical Report WHOI-92-04.

`meanspec`

, `specprop`

```
data(tico)
note <- cutw(tico, from=0.5, to=0.9, output="Wave")
## default setting
acoustat(note)
## change the percentile fraction
acoustat(note, fraction=50)
## change the STFT parameters
acoustat(note, wl=1024, ovlp=80)
## change the function to compute the aggregate contours
## standard deviation instead of sum
acoustat(note, aggregate=sd)
## direct time and frequency selection
acoustat(tico, tlim=c(0.5,0.9), flim=c(3,6))
## some useless graphical changes
acoustat(note, type="o", col="blue")
```

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.