Description Usage Arguments Details Value Author(s) See Also Examples

This function computes the Fourier analysis of a time wave envelope. This allows to detect periodicity, in particular those generated by amplitude modulations.

1 |

`wave` |
an R object. |

`f` |
sampling frequency of |

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

`envt` |
the type of envelope to be used: either "abs" for absolute amplitude envelope or "hil" for Hilbert amplitude envelope. |

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

`plot` |
logical, if |

`type` |
if |

`...` |
other |

This function is based on `env`

and `meanspec`

.

The envelope of `wave`

is first computed and the spectrum of this envelope
is then processed. All `env`

and `meanspec`

arguments can be
set up. Be sure to set up `wl`

large enough if you want to detect low amplitude
modulation periodicity.

If `plot`

is `FALSE`

, `ama`

returns a numeric
vector corresponding to the computed spectrum.
If `peaks`

is not `NULL`

, `ama`

returns a list with
two elements:

`spec` |
the spectrum computed |

`peaks ` |
the peaks values (in kHz). |

Jerome Sueur sueur@mnhn.fr

1 2 3 4 5 6 7 | ```
data(orni)
# detection of the main amplitude modulation in a cicada song:
# one with a 0.258 kHz frequency (due to pulses in the echemes)
# one with a 2.369 kHz frequency (fundamental frequency)
ama(orni,f=22050,wl=1024)
# these amplitude modulations can be identify with a cursor:
ama(orni,f=22050,wl=1024,identify=TRUE)
``` |

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