Generate sample stimuliΒΆ

This shows how to generate some simple stimuli. It will also play a couple of sample stimuli.

generate simple stimuli
from os import path as op
import numpy as np
import matplotlib.pyplot as plt

from import write_hdf5, write_wav
from expyfun.stimuli import play_sound


def generate_stimuli(num_trials=10, num_freqs=4, stim_dur=0.5, min_freq=500.0,
                     max_freq=4000.0, fs=24414.0625, rms=0.01, output_dir='.',
                     save_as='hdf5', rand_seed=0):
    """Make some sine waves and save in various formats. Optimized for saving
    as MAT files, but can also save directly as WAV files, or can return a
    python dictionary with sinewave data as values.

    num_trials : int
        Number of trials you want in your experiment. Ignored if save_as is
        not 'mat'.
    num_freqs : int
        Number of frequencies (equally-spaced on a log2-scale) at which to
        generate tones.
    stim_dur : float
        Duration of the tones in seconds.
    min_freq : float
        Frequency of the lowest tone in Hertz.
    max_freq : float
        Frequency of the highest tone in Hertz.
    fs : float | None
        Sampling frequency of resulting sinewaves.  Defaults to 24414.0625 (a
        standard rate for TDTs).
    rms : float
        RMS amplitude to which all sinwaves will be scaled.
    output_dir : str
        Directory to output the files into.
    save_as : str | None
        Format in which to return the sinewaves. 'dict' returns sinewave arrays
        as values in a python dictionary; 'wav' saves them as WAV files at
        sampling frequency 'fs'; 'mat' saves them as a MAT file along with
        related variables 'fs', 'freqs', 'trial_order', and 'rms'.
        None will not save any data.
    rand_seed : int | None
        Seed for the random number generator.

    wavs : dict | None
        The stimulus dictionary.
    if rand_seed is None:
        rng = np.random.RandomState()
        rng = np.random.RandomState(rand_seed)

    # check input arguments
    if save_as is not None and save_as not in ['dict', 'wav', 'hdf5']:
        raise ValueError('"save_as" must be "dict", "wav", or "hdf5"')

    fs = float(fs)
    t = np.arange(np.round(stim_dur * fs)) / fs

    # frequencies equally spaced on a log-2 scale
    freqs = min_freq * np.logspace(0, np.log2(max_freq / float(min_freq)),
                                   num_freqs, endpoint=True, base=2)

    # strings for the filenames / dictionary keys
    freq_names = [str(int(f)) for f in freqs]
    names = ['stim_%s_%s' % (n, f) for n, f in enumerate(freq_names)]

    # generate sinewaves & RMS normalize
    wavs = [np.sin(2 * np.pi * f * t) for f in freqs]
    wavs = [rms / np.sqrt(np.mean(w ** 2)) * w for w in wavs]

    # collect into dictionary & save
    wav_dict = {n: w for (n, w) in zip(names, wavs)}
    if save_as == 'hdf5':
        num_reps = num_trials // num_freqs + 1
        trials = np.tile(range(num_freqs), num_reps)
        trial_order = rng.permutation(trials[0:num_trials])
        wav_dict.update({'trial_order': trial_order, 'freqs': freqs, 'fs': fs,
                         'rms': rms})
        write_hdf5(op.join(output_dir, 'equally_spaced_sinewaves.hdf5'),
                   wav_dict, overwrite=True)
    elif save_as == 'wav':
        for n in names:
            write_wav(op.join(output_dir, n + '.wav'), wav_dict[n], int(fs))
    return wav_dict

if __name__ == '__main__':
    wav_dict = generate_stimuli(save_as=None)

Total running time of the script: ( 0 minutes 0.074 seconds)

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