myogen.simulator.IntramuscularEMG.add_noise#

IntramuscularEMG.add_noise(
snr__dB: float,
noise_type: str = 'gaussian',
*,
spectral_slope: float = -0.5,
excess_kurtosis: float = 3.0,
powerline_hz: float = 50.0,
powerline_amplitude: float = 0.1,
powerline_harmonic_ratios: list[float] | None = None,
powerline_frequency_drift_hz: float = 0.3,
powerline_amplitude_modulation_depth: float = 0.15,
peak_hz: float = 1000.0,
analog_hpf_hz: float = 10.0,
baseline_drift_rms_uv: float = 0.0,
baseline_drift_alpha: float = 1.75,
baseline_drift_low_hz: float | None = None,
baseline_drift_high_hz: float = 1.0,
) → INTRAMUSCULAR_EMG__Block[source]#

Add noise to the electrode array.

Two noise models are available:

  • "gaussian" – white Gaussian noise (legacy default). Each electrode channel gets independent normal noise scaled to hit the requested per-channel SNR.

  • "realistic" – spectrally colored noise calibrated against real bipolar fine-wire iEMG recordings (TEP / Synergy studies). 1/f-like base, mid-band spectral emphasis from electrode–amplifier bandwidth, heavy tails from cross-talk artifacts, and additive 50/60 Hz powerline interference with harmonics. See myogen.utils.emg_noise for the math.

Per-channel SNR is preserved across both modes: each electrode’s noise RMS is computed from that channel’s own signal RMS so electrodes with different amplitudes get appropriately scaled noise.

Parameters:

  • snr__dB (float) – Signal-to-noise ratio in dB. Higher values result in cleaner signals. Typical intramuscular EMG has SNR ranging from 15–50 dB. Applied independently to each electrode channel.

  • noise_type ({"gaussian", "realistic"}, default="gaussian") – Noise model to use. "realistic" activates the colored noise pipeline; the remaining keyword-only parameters then apply.

  • spectral_slope (float, default=-0.5) – PSD slope in log–log space for the colored-noise base. 0 = white, -1 = pink. Real iEMG: -0.4 to -0.8. Ignored when noise_type="gaussian".

  • excess_kurtosis (float, default=3.0) – Target excess kurtosis (0 = Gaussian). Controlled isometric iEMG: 1–6. Dynamic tasks: higher. Ignored when noise_type="gaussian".

  • powerline_hz (float, default=50.0) – Powerline interference frequency. Use 60.0 for North America, 0.0 to disable. Ignored when noise_type="gaussian".

  • powerline_amplitude (float, default=0.1) – Powerline fundamental amplitude as a fraction of noise RMS. Set to 0 (or powerline_hz=0) to disable. Ignored when noise_type="gaussian".

  • powerline_harmonic_ratios (list of float, optional) – Per-harmonic amplitude ratios relative to the fundamental. None uses the default [1.0, 0.5, 0.3, 0.15, 0.08] (fundamental + 4 harmonics). Ignored when noise_type="gaussian".

  • powerline_frequency_drift_hz (float, default=0.3) – Standard deviation (Hz) of the slow random walk of the mains instantaneous frequency. Broadens each line peak from a delta into a ~2-5 Hz FWHM bump (typical of real recordings). Set to 0 for a pure-tone powerline. Ignored when noise_type="gaussian".

  • powerline_amplitude_modulation_depth (float, default=0.15) – Fractional AM depth (±15% by default) applied to each powerline harmonic — adds narrow sidebands within ±2 Hz of every line. Set to 0 to disable. Ignored when noise_type="gaussian".

  • peak_hz (float, default=1000.0) – Center frequency of the mid-band spectral emphasis from electrode–amplifier bandwidth interaction. Ignored when noise_type="gaussian".

  • baseline_drift_rms_uv (float, default=0.0) – Target RMS (post-HPF) of a band-limited 1/f^α baseline drift representing electrode/interface noise (Huigen 2002, Gondran 1996). Same units as the EMG block. Set to 0 (the default) to disable, preserving legacy behaviour. The spectral form is paper-constrained; the amplitude defaults are not validated for intramuscular EMG — calibrate against real recordings via myogen.utils.calibrate_baseline_drift_profile(). Broadband movement artifacts (0–20 Hz, De Luca 2010) are a separate phenomenon out of scope here. Ignored when noise_type="gaussian".

  • baseline_drift_alpha (float, default=1.75) – Drift PSD slope α (PSD ∝ 1/f^α). Midpoint of the [1.5, 2.0] electrode-noise regime. Must be > 0. Ignored when noise_type="gaussian".

  • baseline_drift_low_hz (float or None, default=None) – Lower edge of the drift band, in Hz. None resolves to the lowest nonzero FFT bin available for the simulation length. Ignored when noise_type="gaussian".

  • baseline_drift_high_hz (float, default=1.0) – Upper edge of the drift band, in Hz. Default keeps the knob scoped to sub-1 Hz baseline wander. Ignored when noise_type="gaussian".

  • analog_hpf_hz (float)

Returns:

Noisy intramuscular EMG signals for the electrode array as a neo.Block. Results are also stored on noisy_intramuscular_emg__Block.

Return type:

INTRAMUSCULAR_EMG__Block

Raises:

ValueError – If intramuscular EMG has not been simulated (call simulate_intramuscular_emg() first) or noise_type is unrecognized.