Class NoiseProfile

contains info re noise profile of an entire spectrogram.

Inheritance
Object
NoiseProfile
Inherited Members
Namespace: AudioAnalysisTools.DSP
Assembly: AudioAnalysisTools.dll
Syntax
public class NoiseProfile

Properties

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MaxDb

Declaration
public double[] MaxDb { get; set; }
Property Value
Type Description
Double[]
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MinDb

Declaration
public double[] MinDb { get; set; }
Property Value
Type Description
Double[]
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NoiseMean

Declaration
public double[] NoiseMean { get; set; }
Property Value
Type Description
Double[]
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NoiseMedian

Declaration
public double[] NoiseMedian { get; set; }
Property Value
Type Description
Double[]
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NoiseMode

Declaration
public double[] NoiseMode { get; set; }
Property Value
Type Description
Double[]
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NoiseSd

Declaration
public double[] NoiseSd { get; set; }
Property Value
Type Description
Double[]
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NoiseThresholds

Declaration
public double[] NoiseThresholds { get; set; }
Property Value
Type Description
Double[]

Methods

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CalculateBackgroundNoise(Double[,])

(1) MODAL METHOD Calculates the modal background noise for each freqeuncy bin. Return the smoothed modal profile. Set the default zero value for number of SDs.

Declaration
public static double[] CalculateBackgroundNoise(double[, ] spectrogram)
Parameters
Type Name Description
Double[,] spectrogram

Assumes the passed spectrogram is oriented as: rows=frames, cols=freq bins.
Returns
Type Description
Double[]
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CalculateMeanNoiseProfile(Double[,])

(1) MEAN SUBTRACTION Assumes the passed matrix is a spectrogram. i.e. rows=frames, cols=freq bins. Returns the noise profile over freq bins. i.e. one noise value per freq bin. Note that NoiseThresholds array is identical to NoiseMedian array.

Declaration
public static NoiseProfile CalculateMeanNoiseProfile(double[, ] matrix)
Parameters
Type Name Description
Double[,] matrix

the spectrogram with origin top-left.
Returns
Type Description
NoiseProfile
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CalculateMedianNoiseProfile(Double[,])

(1) MEDIAN SUBTRACTION Assumes the passed matrix is a spectrogram. i.e. rows=frames, cols=freq bins. Returns the noise profile over freq bins. i.e. one noise value per freq bin. Note that NoiseThresholds array is identical to NoiseMedian array.

Declaration
public static NoiseProfile CalculateMedianNoiseProfile(double[, ] matrix)
Parameters
Type Name Description
Double[,] matrix

the spectrogram with origin top-left.
Returns
Type Description
NoiseProfile
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CalculateModalNoiseProfile(Double[,], Double)

(1) MODAL METHOD Assumes the passed matrix is a spectrogram. i.e. rows=frames, cols=freq bins. Returns the noise profile over freq bins. i.e. one noise value per freq bin.

Declaration
public static NoiseProfile CalculateModalNoiseProfile(double[, ] matrix, double sdCount)
Parameters
Type Name Description
Double[,] matrix

the spectrogram with origin top-left.
Double sdCount

number of standard deviations.
Returns
Type Description
NoiseProfile
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CalculateModalNoiseUsingStartFrames(Double[,], Int32)

(4) FIRST N FRAMES IMPORTANT: this method assumes that the first N frames (N=frameCount) DO NOT contain signal.

Declaration
public static double[] CalculateModalNoiseUsingStartFrames(double[, ] matrix, int firstNFramesCount)
Parameters
Type Name Description
Double[,] matrix

the spectrogram rotated with origin is top-left.
Int32 firstNFramesCount

the first N rows of the spectrogram.
Returns
Type Description
Double[]
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CalculatePercentileNoiseProfile(Double[,], Int32)

Declaration
public static NoiseProfile CalculatePercentileNoiseProfile(double[, ] matrix, int percentile)
Parameters
Type Name Description
Double[,] matrix
Int32 percentile
Returns
Type Description
NoiseProfile
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GetNoiseProfile_BinWiseFromLowestPercentileCells(Double[,], Int32)

(3) BIN-WISE LOWEST PERCENTILE CELLS METHOD Assumes the passed matrix is a spectrogram. Returns the noise profile over freq bins. i.e. one noise value per freq bin. IMPORTANT: This is the preferred method to estiamte a noise profile for short recordings i.e LT approx 10-15 seconds long.

Declaration
public static double[] GetNoiseProfile_BinWiseFromLowestPercentileCells(double[, ] matrix, int lowPercentile)
Parameters
Type Name Description
Double[,] matrix

the spectrogram whose rows=frames, cols=freq bins.
Int32 lowPercentile

The percent of lowest energy frames to be included in calculation of the noise profile.
Returns
Type Description
Double[]
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GetNoiseProfile_fromLowestPercentileFrames(Double[,], Int32)

(2) LOWEST PERCENTILE FRAMES METHOD Assumes the passed matrix is a spectrogram and that all values in the data matrix are positive. Returns the noise profile over freq bins. i.e. one noise value per freq bin. First calculate the frame averages, sort in ascending order and accumulate the first N% of frames. WARNING: This method should NOT be used for short recordings i.e LT approx 10-15 seconds long.

Declaration
public static double[] GetNoiseProfile_fromLowestPercentileFrames(double[, ] matrix, int lowPercentile)
Parameters
Type Name Description
Double[,] matrix

the spectrogram whose rows=frames, cols=freq bins.
Int32 lowPercentile

The percent of lowest energy frames to be included in calculation of the noise profile.
Returns
Type Description
Double[]

Returns a noise profile consisting of averaged values from the selected X% of low energy frames.

Extension Methods