Remove line noise with CleanLine

Removes power-line noise (and optional harmonics) by sliding-window sinusoidal regression with a Thomson F-test (the CleanLine / Chronux approach; Mitra & Bokil, 2008). In each Hann-overlapped window each channel is regressed onto the line sine/cosine pair; when the fit is significant (p < p_thresh) the fitted sinusoid is subtracted. This attenuates the line deeply without a wide spectral notch and works on any number of channels.

Usage

cleanLine(
  x,
  line_freq = 50,
  bandwidth = 2,
  harmonics = 1,
  p_thresh = 0.01,
  window_sec = 4,
  assay_name = NULL,
  output_assay = "cleanline"
)

Arguments

x: A PhysioExperiment object with a 2D (time x channels) assay.
line_freq: Line frequency in Hz (default: 50).
bandwidth: Reserved spectral bandwidth in Hz around the line (default: 2).
harmonics: Number of harmonics to remove, including the fundamental (default: 1, i.e. line_freq only; 3 removes 50/100/150 Hz).
p_thresh: F-test significance threshold for subtracting the line (default: 0.01).
window_sec: Sliding-window length in seconds (default: 4).
assay_name: Input assay (default: defaultAssay(x)).
output_assay: Name for the cleaned assay (default: "cleanline").

Value

The PhysioExperiment with the cleaned signal in output_assay; the removed line-power fraction is stored in metadata(x)$line_noise and logged in provenance.

References

Mitra, P., & Bokil, H. (2008). Observed Brain Dynamics. Oxford University Press.

Usage

Arguments

Value

References

See also