Modules¶

Generators¶

Module containing various generator functions:

whiteNoise: Adds White Gaussian Noise of approx. 16dB crest to a FFT block.
gauss_grid: Compute Gauss-Legendre quadrature nodes and weights in the SOFiA / VariSphear data format.
lebedev: Compute Lebedev quadrature nodes and weights given a maximum stable order. Alternatively, a degree may be supplied.
radial_filter: Generate modal radial filter of specified orders and frequencies.
radial_filter_fullspec: Generate NFFT/2 + 1 modal radial filter of orders 0:max_order for frequencies 0:fs/2, wraps radial_filter().
spherical_head_filter: Generate coloration compensation filter of specified maximum SH order.
spherical_head_filter_spec: Generate NFFT/2 + 1 coloration compensation filter of specified maximum SH order for frequencies 0:fs/2, wraps spherical_head_filter().
tapering_window: Design tapering window with cosine slope for orders greater than 3.
sampled_wave: Returns the frequency domain data of an ideal wave as recorded by a provided array.
ideal_wave: Ideal wave generator, returns spatial Fourier coefficients Pnm of an ideal wave front hitting a specified array.
spherical_noise: Returns order-limited random weights on a spherical surface.
delay_fd: Generate delay in frequency domain that resembles a circular shift in time domain.

I/O¶

Module containing various input and output functions:

TimeSignal: Named tuple to store time domain data and related metadata.
SphericalGrid: Named tuple to store spherical sampling grid geometry.
ArrayConfiguration: Named tuple to store microphone array characteristics.
ArraySignal: Named tuple to store microphone array data in terms of TimeSignal, SphericalGrid and ArrayConfiguration
HrirSignal: Named tuple to store Head Related Impulse Response grid data in terms of TimeSignal for either ear and SphericalGrid
read_miro_struct: Read Head Related Impulse Responses (HRIRs) or Array / Directional Impulse Responses (DRIRs) stored as MIRO Matlab files and convert them to ArraySignal.
read_SOFA_file: Read Head Related Impulse Responses (HRIRs) or Array / Directional Impulse Responses (DRIRs) stored as Spatially Oriented Format for Acoustics (SOFA) files and convert them to ArraySignal or HrirSignal.
empty_time_signal: Returns an empty np rec array that has the proper data structure.
load_array_signal: Convenience function to load ArraySignal saved into np data structures.
read_wavefile: Reads in WAV files and returns data [Nsig x Nsamples] and fs.
write_SSR_IRs: Takes two time signals and writes out the horizontal plane as HRIRs for the SoundScapeRenderer. Ideally, both hold 360 IRs but smaller sets are tried to be scaled up using repeat.

Lebedev¶

Module to generate Lebedev grids and quadrature weights for degrees 6, 14, 26, 38, 50, 74, 86, 110, 146, 170, 194:

genGrid(n): Generate Lebedev grid geometry of degree n.

Adapted from Richard P. Mullers Python version, https://github.com/gabrielelanaro/pyquante/blob/master/Data/lebedev_write.py C version: Dmitri Laikov F77 version: Christoph van Wuellen, http://www.ccl.net

Users of this code are asked to include reference 3 in their publications, and in the user- and programmers-manuals describing their codes.

References

3: V.I. Lebedev, and D.N. Laikov ‘A quadrature formula for the sphere of the 131st algebraic order of accuracy’ Doklady Mathematics, Vol. 59, No. 3, 1999, pp. 477-481.

Plotting¶

Module containing various plotting functions:

makeMTX: Returns a plane wave decomposition over a full sphere.
makeFullMTX: Generates visualization matrix for a set of spatial fourier coefficients over all kr.
plot2D: Visualize 2D data using plotly.
plot3D: Visualize matrix data, such as from makeMTX(Pnm, dn).
plot3Dgrid: Visualize matrix data in a grid, such as from makeMTX(Pnm, dn).

Processing¶

Module containing functions to act on the Spatial Fourier Coefficients.

BEMA: Perform Bandwidth Extension for Microphone Arrays (BEMA) spatial anti-aliasing.
FFT: Perform real-valued Fast Fourier Transform (FFT).
iFFT: Perform inverse real-valued (Fast) Fourier Transform (iFFT).
spatFT: Perform spatial Fourier transform.
spatFT_RT: Perform spatial Fourier transform for real-time applications (otherwise use spatFT() for more more convenience and flexibility).
spatFT_LSF: Perform spatial Fourier transform by least square fit to provided data.
iSpatFT: Perform inverse spatial Fourier transform.
plane_wave_decomp: Perform plane wave decomposition.
rfi: Perform radial filter improvement (RFI)
sfe: Perform sound field extrapolation (SFE) - WORK IN PROGRESS.
wdr: Perform Wigner-D rotation (WDR) - NOT YET IMPLEMENTED.
convolve: Convolve two arrays A & B row-wise where one or both can be one-dimensional for SIMO/SISO convolution.

Spherical¶

Module containing various spherical harmonics helper functions:

besselj / neumann: Bessel function of first and second kind of order n at kr.
hankel1 / hankel2: Hankel function of first and second kind of order n at kr.
spbessel / spneumann: Spherical Bessel function of first and second kind of order n at kr.
sphankel1 / sphankel2: Spherical Hankel of first and second kind of order n at kr.
dspbessel / dspneumann: Derivative of spherical Bessel of first and second kind of order n at kr.
dsphankel1 / dsphankel2: Derivative spherical Hankel of first and second kind of order n at kr.
spherical_extrapolation: Factor that relate signals recorded on a sphere to it’s center.
array_extrapolation: Factor that relate signals recorded on a sphere to it’s center. In the rigid configuration, a scatter_radius that is different to the array radius may be set.
sph_harm: Compute spherical harmonics.
sph_harm_large: Compute spherical harmonics for large orders > 84.
sph_harm_all: Compute all spherical harmonic coefficients up to degree nMax.
mnArrays: Generate degrees n and orders m up to nMax.
reverseMnIds: Generate reverse indexes according to stacked coefficients of orders m up to nMax.
cart2sph / sph2cart: Convert cartesian to spherical coordinates and vice versa.
kr: Generate kr vector for given f and array radius.
kr_full_spec: Generate full spectrum kr.

Utilities¶

Module containing various utility functions:

env_info: Guess environment based on sys.modules.
progress_bar: Display a spinner or a progress bar.
db: Convenience function to calculate the 20*log10(abs(x)).
cart2sph / sph2cart: Transform cartesian into spherical coordinates and vice versa.
SOFA_grid2acr: Transform coordinate grid with specified coordinate system definition from a SOFA file into spherical coordinates in radians.
nearest_to_value / nearest_to_value_IDX / nearest_to_value_logical_IDX: Returns nearest value inside an array.
interleave_channels: Interleave left and right channels. Style == ‘SSR’ checks if we total 360 channels.
simple_resample: Wrap scipy.signal.resample with a simpler API.
scalar_broadcast_match: Returns arguments as np.array, if one is a scalar it will broadcast the other one’s shape.
frq2kr: Returns the kr bin closest to the target frequency.
stack: Stacks two 2D vectors along the same-sized dimension or the smaller one.
zero_pad_fd: Apply zero padding to frequency domain data by transformation into time domain and back.
current_time: Return current system time based on datetime.now().
time_it: Measure execution of a specified statement which is useful for the performance analysis. In this way, the execution time and respective results can be directly compared.