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DIETZ2011 - Dietz 2011 binaural model

Usage

[...] = dietz(insig,fs);

Input parameters

`insig`	binaural signal for which values should be calculated
`fs`	sampling rate (Hz)

Output parameters

`fine`	Information about the fine structure (see below)
`env`	Information about the envelope (see below)

Description

dietz2011(insig,fs) calculates interaural phase, time and level differences of fine- structure and envelope of the signal, as well as the interaural coherence, which can be used as a weighting function.

The output structures fine and env have the following fields:

`.s1`	Left signal as put in the binaural processor
`.s2`	Right signal as put in the binaural processor
`.fc`	Center frequencies of the channels (f_carrier or f_mod)
`.itf`	Transfer function
`.itf_equal`	Transfer function without amplitude
`.ipd`	Phase difference in rad
`.ipd_lp`	Based on lowpass-filtered itf, phase difference in rad
`.ild`	Level difference in dB
`.itd`	Time difference based on instantaneous frequencies
`.itd_C`	Time difference based on central frequencies
`.itd_lp`	As .itd, with low-passed itf
`.itd_C_lp`	As .itd_C, with low-passed itf
`.f_inst_1`	Instantaneous frequencies in the channels of the filtered s1
`.f_inst_2`	Instantaneous frequencies in the channels of the filtered s2
`.f_inst`	Instantaneous frequencies (average of f_inst1 and 2)

The steps of the binaural model to calculate the result are the following (see also Dietz et al., 2011):

Middle ear filtering (500-2000 Hz 1st order bandpass)
Auditory bandpass filtering on the basilar membrane using a 4th-order all-pole gammatone filterbank, employing 23 filter bands between 200 and 5000 Hz, with a 1 ERB spacing. The filter width was set to correspond to 1 ERB.
Cochlear compression was simulated by power-law compression with an exponent of 0.4.
The transduction process in the inner hair cells was modelled using half-wave rectification followed by filtering with a 770-Hz 5th order lowpass.

The interaural temporal disparities are then extracted using a second-order complex gammatone bandpass (see paper for details).

dietz2011 accepts the following optional parameters:

`'flow',flow`	Set the lowest frequency in the filterbank to flow. Default value is 200 Hz.
`'fhigh',fhigh`	Set the highest frequency in the filterbank to fhigh. Default value is 5000 Hz.
`'basef',basef`	Ensure that the frequency basef is a center frequency in the filterbank. The default value is 1000.
`'filters_per_ERB',filters_per_erb`
	Filters per erb. The default value is 1.
`'middle_ear_thr',r`	Bandpass freqencies for middle ear transfer. The default value is `[500 2000]`.
`'middle_ear_order',n`
	Order of middle ear filter. Only even numbers are possible. The default value is 2.
`'haircell_lp_freq',hlpfreq`
	Cutoff frequency for haircell lowpass filter. The default value is 770.
`'haircell_lp_order',hlporder`
	Order of haircell lowpass filter. The default value is 5.
`'compression_power',cpwr`
	The default value is 0.4.
`'alpha',alpha`	Internal noise strength. Convention FIXME 65dB = 0.0354. The default value is 0.
`'int_randn'`	Internal noise XXX. This is the default.
`'int_mini'`	Internal noise XXX.
`'filter_order',fo`	Filter order for output XXX. Used for both 'mod' and 'fine'. The default value is 2.
`'filter_attenuation_db',fadb`
	Used for both 'mod' and 'fine'. The default value is 10.
`'fine_filter_finesse',fff`
	Only for finestructure plugin. The default value is 3.
`'mod_center_frequency_hz',mcf_hz`
	Only for envelope plugin. The default value is 135.
`'mod_filter_finesse',mff`
	Only for envelope plugin. The default value is 8.
`'level_filter_cutoff_hz',lfc_hz`
	For ild- or level-plugin. The default value is 30.
`'level_filter_order',lforder`
	For ild- or level-plugin. The default value is 2.
`'coh_param',coh_param`
	This is a structure used for the localization plugin. It has the following fields: `max_abs_itd` The default value is 1e-3. `tau_cycles` The default value is 5. `tau_s` The default value is 10e-3.
`'signal_level_dB_SPL',signal_level`
	Sound pressure level of left channel. Used for data display and analysis. Default value is 70.

References: