annotate filter/formulae.c @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

/*
    Copyright (c) Applied Psychology Unit, Medical Research Council. 1988, 1989
    ===========================================================================

    Permission to use, copy, modify, and distribute this software without fee 
    is hereby granted for research purposes, provided that this copyright 
    notice appears in all copies and in all supporting documentation, and that 
    the software is not redistributed for any fee (except for a nominal shipping 
    charge). Anyone wanting to incorporate all or part of this software in a
    commercial product must obtain a license from the Medical Research Council.

    The MRC makes no representations about the suitability of this 
    software for any purpose.  It is provided "as is" without express or implied 
    warranty.
 
    THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
    ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE
    A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY 
    DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN 
    AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

/*

	formulae.c
	==========

    Functions from : Moore and Glasberg, Formulae describing frequency
    selectivity as a function or frequency and level, and their use in
    calculating excitation paterns. Hearing reserch, 28 (1987) 209-225

*/

#include <math.h>
#include <stdio.h>
#include "../glib/options.h"

#ifndef  _FORMULAE_H_
#include "formulae.h"
#endif

/* latest erb function circa. 1989 from BBG & CJM */

/* derived from erb = 24.7 * ( 4.37e-3 * f +  1 ) */


static double limit = 24.7  ; /* limit = k1 */
static double Q     = 9.265 ; /* Q = 1. / ( k1 * k2 ) */


void SetErbParameters( new_limit, new_Q )
double new_limit, new_Q ;
{
    limit = new_limit ;
    Q     = new_Q     ;

    return ;
}


double Erb( frequency )
     double frequency ;
{
    return ( limit + frequency / Q ) ;
}

/* integrate 1/erb(f) to get erb based scale */

double ErbScale( frequency )
	  double frequency ;
{
    return ( log( 1. + frequency / Q / limit ) * Q ) ;
}


double FofErbScale( E )
	     double E ;
{
  return ( ( exp( E / Q ) - 1 ) * Q * limit ) ;
}


double poly( coefts, x )
double *coefts, x ;
{
    double *cptr = coefts ;
    double power = 1 ;
    double value = 0 ;

    while( *cptr != 0. ) {
	value += *cptr++ * power ;
	power *= x ;
    }

    return ( value ) ;
}

double dBAudiogram( frequency )
	     double frequency ;
{
    static double audiogram_polynomial_coeficients[] = {
	  2661.8, -3690.1, 1917.4, -440.77, 37.706, 0. } ;

    return ( poly( audiogram_polynomial_coeficients, log10( frequency ) ) ) ;
}

double Audiogram( frequency )
	   double frequency ;
{
    return ( pow( 10., -dBAudiogram( frequency ) / 20. ) ) ;
}


/* old versions of above */

static double erb_a  = {  6.23e-6 },
	      erb_b  = { 93.39e-3 },
	      erb_c  = { 28.52    } ;

/* erb rate function coeficients */

static double erb_k1 = {  11.17   },
	      erb_k2 = {   0.312  },
	      erb_k3 = {  14.675  },
	      erb_k4 = {  43.0    } ;

static double     b0 = {  2661.8  },
		  b1 = {  3690.1  },
		  b2 = {  1917.4  },
		  b3 = {  440.77  },
		  b4 = {  37.706  } ;

double OldErb( f )
double f ;
{
    return ( erb_a * f * f + erb_b * f + erb_c ) ;
}

double OldErbScale( f )
double f ;
{
    double fkHz ;

    fkHz = f / 1000. ;

    return ( erb_k1 * log( ( fkHz + erb_k2 ) / ( fkHz + erb_k3 ) ) + erb_k4 ) ;
}

double OldFofErbScale( E )
double E ;
{
    double tmp ;

    tmp = exp( ( E - erb_k4 ) / erb_k1 ) ;

    return ( ( erb_k2 - erb_k3 * tmp ) / ( tmp - 1.0 ) * 1000. ) ;
}