outsig = lopezpoveda2001(insig,fs);

`lopezpoveda2001(insig,fs)` computes the Dual Resonance Non-Linear (lopezpoveda2001)
filterbank of the input signal insig sampled at *fs* Hz with channels
specified by the center frequencies in *fc*. The lopezpoveda2001 is described in
the paper Lopez-Poveda and Meddis (2001). The lopezpoveda2001 models the basilar
membrane non-linearity.

This version of the lopezpoveda2001 incoorperate the middleear filter used in Lopez-Poveda and Meddis (2001).

The lopezpoveda2001 takes a lot of parameters which vary over frequency. Such a
parameter is described by a \(1 \times 2\) vector `[b a]` and indicates
that the value of the parameter at frequency *fc* can be calculated by

\begin{equation*}
10^{b+a\cdot log_{10}(fc)}
\end{equation*}

The parameters are:

'flow',flow |
Set the lowest frequency in the filterbank to
flow. Default value is 80 Hz. |

'fhigh',fhigh |
Set the highest frequency in the filterbank to
fhigh. Default value is 8000 Hz. |

'basef',basef |
Ensure that the frequency basef is a centre frequency
in the filterbank. The default value of [] means
no default. |

'middleear' |
Perform middleear filtering before the actual lopezpoveda2001 is applied using the middleear filter specified in Lopez-Poveda and Meddis (2001), and compensate for the effect of the filter after lopezpoveda2001 filtering. This is the default. |

'no_middleear' |
No middleear filtering. Be carefull with this setting, as another scaling must then be perform to convert the input to stapes movement. |

'bothparts' |
Compute both the linear and the non-linear path of the lopezpoveda2001. This is the default. |

'linonly' |
Compute only the linear path. |

'nlinonly' |
Compute only the non-linear path. |

'lin_ngt',n |
Number of cascaded gammatone filter in the linear part, default value is 2. |

'lin_nlp',n |
Number of cascaded lowpass filters in the linear part, default value is 4 |

'lin_gain',g |
Gain in the linear part, default value is [4.20405 ... .47909]. |

'lin_fc',fc |
Centre frequencies of the gammatone filters in the linear part. Default value is [-0.06762 1.01679]. |

'lin_bw',bw |
Bandwidth of the gammatone filters in the linear part. Default value is [.03728 .78563] |

'lin_lp_cutoff',c |
Cutoff frequency of the lowpass filters in the linear part. Default value is [-0.06762 1.01679 ] |

'nlin_ngt_before',n |
Number of cascaded gammatone filters in the non-linear part before the broken stick non-linearity. Default value is 3. |

'nlin_ngt_after',n |
Number of cascaded gammatone filters in the non-linear part after the broken stick non-linearity. The default value of [] means to use the 'before' value. |

'nlin_nlp',n |
Number of cascaded lowpass filters in the non-linear part. Default value is 3. |

'nlin_fc_before',fc |
Center frequencies of the gammatone filters in the non-linear part before the broken stick non-linearity. Default value is [-0.05252 1.01650]. |

'nlin_fc_after',fc |
Center frequencies of the gammatone filters in the
non-linear part after the broken stick
non-linearity. The default value of [] means to use the 'before'
value. |

'nlin_bw_before',bw |
Bandwidth of the gammatone filters in the non-linear part before the broken stick non-linearity. Default value is [-0.03193 .77426 ]. |

'nlin_bw_after',w |
Bandwidth of the gammatone filters in the non-linear
part after the broken stick non-linearity. The default
value of [] means to use the 'before' value. |

'nlin_lp_cutoff',c |
Cutoff frequency of the lowpass filters in the non-linear part. Default value is [-0.05252 1.01650 ]. |

'nlin_a',a |
The a coefficient for the broken-stick non-linearity. Default
value is [1.40298 .81916 ]. |

'nlin_b',b |
The b coefficient for the broken-stick non-linearity. Default
value is [1.61912 -.81867]. |

'nlin_c',c |
The c coefficient for the broken-stick non-linearity. Default
value is [-.60206 0]. |

'nlin_d',d |
The d coefficient for the broken-stick non-linearity. Default
value is 1. |

The output from lopezpoveda2001 can be conveniently visualized using the
`plotfilterbank` function from LTFAT.

E. Lopez-Poveda and R. Meddis.
A human nonlinear cochlear filterbank.
*J. Acoust. Soc. Am.*, 110:3107--3118, 2001.

R. Meddis, L. O'Mard, and E. Lopez-Poveda.
A computational algorithm for computing nonlinear auditory frequency
selectivity.
*J. Acoust. Soc. Am.*, 109:2852--2861, 2001.