autoCochleagram Sound_to_Cochleagram (Sound me, double dt, double df, double dt_window, double forwardMaskingTime) {
try {
double duration = my nx * my dx;
long nFrames = 1 + (long) floor ((duration - dt_window) / dt);
long nsamp_window = (long) floor (dt_window / my dx), halfnsamp_window = nsamp_window / 2 - 1;
long nf = lround (25.6 / df);
double dampingFactor = forwardMaskingTime > 0.0 ? exp (- dt / forwardMaskingTime) : 0.0; // default 30 ms
double integrationCorrection = 1.0 - dampingFactor;
nsamp_window = halfnsamp_window * 2;
if (nFrames < 2) return autoCochleagram ();
double t1 = my x1 + 0.5 * (duration - my dx - (nFrames - 1) * dt); // centre of first frame
autoCochleagram thee = Cochleagram_create (my xmin, my xmax, nFrames, dt, t1, df, nf);
autoSound window = Sound_createSimple (1, nsamp_window * my dx, 1.0 / my dx);
for (long iframe = 1; iframe <= nFrames; iframe ++) {
double t = Sampled_indexToX (thee.get(), iframe);
long leftSample = Sampled_xToLowIndex (me, t);
long rightSample = leftSample + 1;
long startSample = rightSample - halfnsamp_window;
long endSample = rightSample + halfnsamp_window;
if (startSample < 1) {
Melder_casual (U"Start sample too small: ", startSample,
U" instead of 1.");
startSample = 1;
}
if (endSample > my nx) {
Melder_casual (U"End sample too small: ", endSample,
U" instead of ", my nx,
U".");
endSample = my nx;
}
/* Copy a window to a frame. */
for (long i = 1; i <= nsamp_window; i ++)
window -> z [1] [i] =
( my ny == 1 ? my z[1][i+startSample-1] : 0.5 * (my z[1][i+startSample-1] + my z[2][i+startSample-1]) ) *
(0.5 - 0.5 * cos (2.0 * NUMpi * i / (nsamp_window + 1)));
autoSpectrum spec = Sound_to_Spectrum (window.get(), true);
autoExcitation excitation = Spectrum_to_Excitation (spec.get(), df);
for (long ifreq = 1; ifreq <= nf; ifreq ++)
thy z [ifreq] [iframe] = excitation -> z [1] [ifreq] + ( iframe > 1 ? dampingFactor * thy z [ifreq] [iframe - 1] : 0 );
}
for (long iframe = 1; iframe <= nFrames; iframe ++)
for (long ifreq = 1; ifreq <= nf; ifreq ++)
thy z [ifreq] [iframe] *= integrationCorrection;
return thee;
} catch (MelderError) {
Melder_throw (me, U": not converted to Cochleagram.");
}
}
Cochleagram Sound_to_Cochleagram_edb
(Sound me, double dtime, double dfreq, int hasSynapse, double replenishmentRate,
double lossRate, double returnRate, double reprocessingRate)
{
try {
double duration_seconds = my xmax;
if (dtime < my dx) dtime = my dx;
long ntime = floor (duration_seconds / dtime + 0.5);
if (ntime < 2) return NULL;
long nfreq = floor (25.6 / dfreq + 0.5); // 25.6 Bark = highest frequency
autoCochleagram thee = Cochleagram_create (my xmin, my xmax, ntime, dtime, 0.5 * dtime, dfreq, nfreq);
/* Stages 1 and 2: outer- and middle-ear filtering. */
/* From acoustic sound to oval window. */
for (long ifreq = 1; ifreq <= nfreq; ifreq ++) {
double *response = thy z [ifreq];
/* Stage 3: basilar membrane filtering by gammatones. */
/* From oval window to basilar membrane response. */
double midFrequency_Bark = (ifreq - 0.5) * dfreq;
double midFrequency_Hertz = Excitation_barkToHertz (midFrequency_Bark);
autoSound gammatone = createGammatone (midFrequency_Hertz, 1 / my dx);
autoSound basil = Sounds_convolve (me, gammatone.peek(), kSounds_convolve_scaling_SUM, kSounds_convolve_signalOutsideTimeDomain_ZERO);
/* Stage 4: detection = rectify + integrate + low-pass 500 Hz. */
/* From basilar membrane response to firing rate. */
if (hasSynapse) {
double dt = my dx;
double M = 1; /* Maximum free transmitter. */
double A = 5, B = 300, g = 2000; /* Determine permeability. */
double y = replenishmentRate; /* Meddis: 5.05 */
double l = lossRate, r = returnRate; /* Meddis: 2500, 6580 */
double x = reprocessingRate; /* Meddis: 66.31 */
double h = 50000; /* Convert cleft contents to firing rate. */
double gdt = 1 - exp (- g * dt), ydt = 1 - exp (- y * dt),
ldt = (1 - exp (- (l + r) * dt)) * l / (l + r),
rdt = (1 - exp (- (l + r) * dt)) * r / (l + r),
xdt = 1 - exp (- x * dt);
double kt = g * A / (A + B); /* Membrane permeability. */
double c = M * y * kt / (l * kt + y * (l + r)); /* Cleft contents. */
double q = c * (l + r) / kt; /* Free transmitter. */
double w = c * r / x; /* Reprocessing store. */
for (long itime = 1; itime <= basil -> nx; itime ++) {
double splusA = basil -> z [1] [itime] * 10 + A;
double replenish = M > q ? ydt * (M - q) : 0;
double eject, loss, reuptake, reprocess;
kt = splusA > 0 ? gdt * splusA / (splusA + B) : 0;
eject = kt * q;
loss = ldt * c;
reuptake = rdt * c;
reprocess = xdt * w;
q = q + replenish - eject + reprocess;
c = c + eject - loss - reuptake;
w = w + reuptake - reprocess;
basil -> z [1] [itime] = h * c;
}
}
if (dtime == my dx) {
for (long itime = 1; itime <= ntime; itime ++)
response [itime] = basil -> z [1] [itime];
} else {
double d = dtime / basil -> dx / 2;
double factor = -6 / d / d;
double area = d * sqrt (NUMpi / 6);
double expmin6 = exp (-6), onebyoneminexpmin6 = 1 / (1 - expmin6);
for (long itime = 1; itime <= ntime; itime ++) {
double t1 = (itime - 1) * dtime, t2 = t1 + dtime, mean = 0;
long i1, i2;
long n = Matrix_getWindowSamplesX (basil.peek(), t1, t2, & i1, & i2);
Melder_assert (n >= 1);
if (n <= 2) {
for (long isamp = i1; isamp <= i2; isamp ++)
mean += basil -> z [1] [isamp];
mean /= n;
} else {
double mu = floor ((i1 + i2) / 2.0);
long muint = mu, dint = d;
for (long isamp = muint - dint; isamp <= muint + dint; isamp ++) {
double y = 0;
if (isamp < 1 || isamp > basil -> nx)
Melder_casual ("isamp %ld", isamp);
else
y = basil -> z [1] [isamp];
mean += y * onebyoneminexpmin6 * (exp (factor * (isamp - muint) *
(isamp - muint)) - expmin6);
}
mean /= area;
}
response [itime] = mean;
}
}
}
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, ": not converted to Cochleagram (edb).");
}
}
