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librosa.core.tone¶

librosa.core.tone(frequency, sr=22050, length=None, duration=None, phi=None)[source]¶

Returns a pure tone signal. The signal generated is a cosine wave.

Parameters

frequencyfloat > 0: frequency
srnumber > 0: desired sampling rate of the output signal
lengthint > 0: desired number of samples in the output signal. When both duration and length are defined, length would take priority.
durationfloat > 0: desired duration in seconds. When both duration and length are defined, length would take priority.
phifloat or None: phase offset, in radians. If unspecified, defaults to -np.pi * 0.5.

Returns

tone_signalnp.ndarray [shape=(length,), dtype=float64]: Synthesized pure sine tone signal

Raises

ParameterError

If frequency is not provided.
If neither length nor duration are provided.

Examples

>>> # Generate a pure sine tone A4
>>> tone = librosa.tone(440, duration=1)

>>> # Or generate the same signal using `length`
>>> tone = librosa.tone(440, sr=22050, length=22050)

Display spectrogram

>>> import matplotlib.pyplot as plt
>>> plt.figure()
>>> S = librosa.feature.melspectrogram(y=tone)
>>> librosa.display.specshow(librosa.power_to_db(S, ref=np.max),
...                          x_axis='time', y_axis='mel')
>>> plt.show()