Frequency utilities

This utility provides frequency and fractional octave frequency bands functionalities.

For syntax purposes you should start with:

>>> from pytta import utils as utils

Available functions:

>>> utils.freq_to_band(freq, nthOct, ref, base)
>>> utils.fractional_octave_frequencies(nthOct = 3, freqRange = (20., 20000.), refFreq = 1000., base = 10)
>>> utils.normalize_frequencies(freqs, samplingRate = 44100)
>>> utils.freqs_to_center_and_edges(freqs)
>>> utils.filter_values(freq, values, nthOct = 3)

For further information, check the docstrings for each function mentioned above.

Authors:

João Vitor G. Paes joao.paes@eac.ufsm.br and Caroline Gaudeoso caroline.gaudeoso@eac.ufsm.br Rinaldi Petrolli rinaldi.petrolli@eac.ufsm.br

pytta.utils.freq_to_band(freq: float, nthOct: int, ref: float, base: int) → int[source]

Band number from frequency value.

Parameters:

  • freq (float) – The frequency value.

  • nthOct (int) – How many bands per octave.

  • ref (float) – Frequency of reference, or band number 0.

  • base (int) – Either 10 or 2.

Raises:

ValueError – If base is not 10 nor 2 raises value error.

Returns:

The band number from center.

Return type:

int

pytta.utils.fractional_octave_frequencies(nthOct: int = 3, freqRange: Tuple[float] = (20.0, 20000.0), refFreq: float = 1000.0, base: int = 10) → ndarray[source]

Lower, center and upper frequency values of all bands within range.

Parameters:

  • nthOct (int, optional) – bands of octave/nthOct. The default is 3.

  • freqRange (Tuple[float], optional) – frequency range. These frequencies are inside the lower and higher band, respectively. The default is (20., 20000.).

  • refFreq (float, optional) – Center frequency of center band. The default is 1000..

  • base (int, optional) – Either 10 or 2. The default is 10.

Returns:

freqs – Array with shape (N, 3).

Return type:

numpy.ndarray

pytta.utils.normalize_frequencies(freqs: ndarray, samplingRate: int = 44100) → ndarray[source]

Normalize frequencies for any sampling rate.

Parameters:

  • freqs (np.ndarray) – DESCRIPTION.

  • samplingRate (int, optional) – DESCRIPTION. The default is 44100.

Returns:

DESCRIPTION.

Return type:

TYPE

pytta.utils.freqs_to_center_and_edges(freqs: ndarray) → Tuple[ndarray][source]

Separate the array returned from fractional_octave_frequencies.

The returned arrays corresponde to the center and edge frequencies of the fractional octave bands

Parameters:

freqs (np.ndarray) – Array returned from fractional_octave_frequencies.

Returns:

  • center (np.ndarray) – Center frequencies of the bands.

  • edges (np.ndarray) – Edge frequencies (lower and upper) of the bands.