def loudness_zwicker_time(third_octave_levels, field_type):
"""Calculate Zwicker-loudness for time-varying signals
Calculate the acoustic loudness according to Zwicker method for
time-varying signals.
Normatice reference:
DIN 45631/A1:2010
ISO 532-1:2017 (method 2)
The code is based on C program source code published alongside
with ISO 532-1 standard.
Note that for reasons of normative continuity, as defined in the
preceeding standards, the method is in accordance with
ISO 226:1987 equal loudness contours (instead of ISO 226:2003)
Parameters
----------
third_octave_levels : numpy.ndarray
rms acoustic pressure [Pa] per third octave versus time
(temporal resolution = 0.5ms)
field_type : str
Type of soundfield corresponding to signal ("free" by
default or "diffuse")
Outputs
-------
N : float
Calculated loudness [sones]
N_specific : numpy.ndarray
Specific loudness [sones/bark]
bark_axis : numpy.ndarray
Corresponding bark axis
"""
# Calculate core loudness
num_sample_level = np.shape(third_octave_levels)[1]
core_loudness = np.zeros((21, num_sample_level))
for i in np.arange(num_sample_level - 1):
core_loudness[:, i] = calc_main_loudness(third_octave_levels[:, i], field_type)
#
# Nonlinearity
core_loudness = calc_nl_loudness(core_loudness)
#
# Calculation of specific loudness
loudness = np.zeros(np.shape(core_loudness)[1])
spec_loudness = np.zeros((240, np.shape(core_loudness)[1]))
for i_time in np.arange(np.shape(core_loudness)[1]):
loudness[i_time], spec_loudness[:, i_time] = calc_slopes(
core_loudness[:, i_time]
)
#
# temporal weigthing
filt_loudness = loudness_zwicker_temporal_weighting(loudness)
#
# Decimation from temporal resolution 0.5 ms to 2ms and return
dec_factor = 4
N = filt_loudness[::dec_factor]
N_spec = spec_loudness[:, ::dec_factor]
return N, N_spec
def loudness_zwicker_stationary(spec_third, third_axis=[], field_type="free"):
"""Zwicker-loudness calculation for stationary signals
Calculates the acoustic loudness according to Zwicker method for
stationary signals.
Normatice reference:
ISO 532:1975 (method B)
DIN 45631:1991
ISO 532-1:2017 (method 1)
The code is based on BASIC program published in "Program for
calculating loudness according to DIN 45631 (ISO 532B)", E.Zwicker
and H.Fastl, J.A.S.J (E) 12, 1 (1991).
Note that due to normative continuity, as defined in the
preceeding standards, the method is in accordance with
ISO 226:1987 equal loudness contours (instead of ISO 226:2003)
Parameters
----------
spec_third : numpy.ndarray
A third octave band spectrum [dB ref. 2e-5 Pa]
third_axis : numpy.ndarray
Normalized center frequency of third octave bands [Hz]
field_type : str
Type of soundfield corresponding to spec_third ("free" by
default or "diffuse")
Outputs
-------
N : float
Calculated loudness [sones]
N_specific : numpy.ndarray
Specific loudness [sones/bark]
"""
#
# Input parameters control and formating
fr = [
25,
31.5,
40,
50,
63,
80,
100,
125,
160,
200,
250,
315,
400,
500,
630,
800,
1000,
1250,
1600,
2000,
2500,
3150,
4000,
5000,
6300,
8000,
10000,
12500,
]
if field_type != "diffuse" and field_type != "free":
raise ValueError(
"ERROR: field_type should be either 'diffuse' or 'free'")
if len(spec_third) != 28:
raise ValueError(
"ERROR: spectrum must contains 28 third octave bands values")
if len(third_axis) == 0:
third_axis = fr
elif (len(third_axis) == 28
and np.all(third_axis != fr)) or len(third_axis) < 28:
raise ValueError(
"""ERROR: third_axis does not contains 1/3 oct between 25 and
12.5 kHz. Check the input parameters""")
else:
# TODO: manage spectrum and third_axis longer than 28 (extract data
# between 25 and 12.5 kHz)
pass
# if (min(spec_third) < -60 or max(spec_third) > 120):
# TODO: replace value below -60 by -60 and raise a warning
# raise ValueError(
# """ERROR: Third octave levels must be within interval
# [-60, 120] dB ref. 2e-5 Pa (for model validity) """
# )
#
#
# Calculate main loudness
Nm = calc_main_loudness(spec_third, field_type)
#
# Calculation of specific loudness pattern and integration of overall
# loudness by attaching slopes towards higher frequencies
N, N_specific = calc_slopes(Nm)
return N, N_specific