Class Oscillations2012

NOTE: 21st June 2012.

This class contains methods to detect oscillations in a the sonogram of an audio signal. The method Execute() returns all info about oscillations in the passed sonogram. This method should be called in preference to those in the class OscillationAnalysis. (The latter should be deprecated.)

Inheritance

Object

Oscillations2012

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

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Namespace: AudioAnalysisTools

Assembly: AudioAnalysisTools.dll

Syntax

public static class Oscillations2012

Methods

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CalculateRequiredFrameOverlap(Int32, Int32, Double)

Calculates the optimal frame overlap for the given sample rate, frame width and max oscillation or pulse rate. Pulse rate is determined using a DCT and efficient use of the DCT requires that the dominant pulse sit somewhere 3.4 along the array of coefficients.

Declaration

public static double CalculateRequiredFrameOverlap(int sr, int frameWidth, double maxOscillation)

Parameters

Type	Name	Description
Int32	sr
Int32	frameWidth
Double	maxOscillation

Returns

Type	Description
Double

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ConvertOscillationScores2Events(SpectrogramStandard, Double[], Int32, Int32, Double, Double, Double, TimeSpan)

Converts the Oscillation Detector score array to a list of Oscillation Events.

Declaration

public static List<OscillationEvent> ConvertOscillationScores2Events(SpectrogramStandard spectrogram, double[] scores, int minHz, int maxHz, double scoreThreshold, double minDurationThreshold, double maxDurationThreshold, TimeSpan segmentStartOffset)

Parameters

Type	Name	Description
SpectrogramStandard	spectrogram
Double[]	scores	the array of OD scores.
Int32	minHz	lower freq bound of the acoustic event.
Int32	maxHz	upper freq bound of the acoustic event.
Double	scoreThreshold	threshold.
Double	minDurationThreshold	min threshold.
Double	maxDurationThreshold	max threshold.
TimeSpan	segmentStartOffset	time offset.

Returns

Type	Description
List<OscillationEvent>

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DetectOscillations(SpectrogramStandard, Int32, Int32, Double, Int32, Int32, Double)

Detects oscillations in a given freq bin. there are several important parameters for tuning. a) DCTLength: Good values are 0.25 to 0.50 sec. Do not want too long because DCT requires stationarity. Do not want too short because too small a range of oscillations b) DCTindex: Sets lower bound for oscillations of interest. Index refers to array of coefficient returned by DCT. Array has same length as the length of the DCT. Low freq oscillations occur more often by chance. Want to exclude them. c) MinAmplitude: minimum acceptable value of a DCT coefficient if hit is to be accepted. The algorithm is sensitive to this value. A lower value results in more oscillation hits being returned.

Declaration

public static double[, ] DetectOscillations(SpectrogramStandard sonogram, int minHz, int maxHz, double dctDuration, int minOscilFreq, int maxOscilFreq, double dctThreshold)

Parameters

Type	Name	Description
SpectrogramStandard	sonogram	A spectrogram.
Int32	minHz	min freq bin of search band.
Int32	maxHz	max freq bin of search band.
Double	dctDuration	number of values.
Int32	minOscilFreq	minimum oscillation freq.
Int32	maxOscilFreq	maximum oscillation freq.
Double	dctThreshold	threshold - do not accept a DCT coefficient if its value is less than this threshold.

Returns

Type	Description
Double[,]

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DoDct(Double[], Double[,], Int32)

Declaration

public static double[] DoDct(double[] vector, double[, ] cosines, int lowerDctBound)

Parameters

Type	Name	Description
Double[]	vector
Double[,]	cosines
Int32	lowerDctBound

Returns

Type	Description
Double[]

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Execute(SpectrogramStandard, Int32, Int32, Double, Int32, Int32, Double, Double, Double, Double, out Double[], out List<OscillationEvent>, out Double[,], TimeSpan)

Declaration

public static void Execute(SpectrogramStandard sonogram, int minHz, int maxHz, double dctDuration, int minOscilFreq, int maxOscilFreq, double dctThreshold, double scoreThreshold, double minDuration, double maxDuration, out double[] scores, out List<OscillationEvent> events, out double[, ] hits, TimeSpan segmentStartOffset)

Parameters

Type	Name	Description
SpectrogramStandard	sonogram
Int32	minHz
Int32	maxHz
Double	dctDuration
Int32	minOscilFreq
Int32	maxOscilFreq
Double	dctThreshold
Double	scoreThreshold
Double	minDuration
Double	maxDuration
Double[]	scores
List<OscillationEvent>	events
Double[,]	hits
TimeSpan	segmentStartOffset

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Execute(SpectrogramStandard, Int32, Int32, Double, Int32, Int32, Double, Double, Double, Double, Int32, out Double[], out List<OscillationEvent>, out Double[,], TimeSpan)

Declaration

public static void Execute(SpectrogramStandard sonogram, int minHz, int maxHz, double dctDuration, int minOscilFreq, int maxOscilFreq, double dctThreshold, double scoreThreshold, double minDuration, double maxDuration, int smoothingWindow, out double[] scores, out List<OscillationEvent> events, out double[, ] hits, TimeSpan segmentStartOffset)

Parameters

Type	Name	Description
SpectrogramStandard	sonogram
Int32	minHz
Int32	maxHz
Double	dctDuration
Int32	minOscilFreq
Int32	maxOscilFreq
Double	dctThreshold
Double	scoreThreshold
Double	minDuration
Double	maxDuration
Int32	smoothingWindow
Double[]	scores
List<OscillationEvent>	events
Double[,]	hits
TimeSpan	segmentStartOffset

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GetComponentsWithOscillations(SpectrogramStandard, OscillationParameters, Nullable<Double>, TimeSpan, String)

Declaration

public static (List<EventCommon> SpectralEvents, List<Plot> DecibelPlots) GetComponentsWithOscillations(SpectrogramStandard spectrogram, OscillationParameters op, double? decibelThreshold, TimeSpan segmentStartOffset, string profileName)

Parameters

Type	Name	Description
SpectrogramStandard	spectrogram
OscillationParameters	op
Nullable<Double>	decibelThreshold
TimeSpan	segmentStartOffset
String	profileName

Returns

Type	Description
(T1, T2)<List<EventCommon>, List<Plot>>

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GetOscillationScores(Double[,], Int32, Int32, Double)

Converts the hits derived from the oscillation detector into a score for each frame. NOTE: The oscillation detector skips every second row, so score must be adjusted for this.

Declaration

public static double[] GetOscillationScores(double[, ] hits, int minHz, int maxHz, double freqBinWidth)

Parameters

Type	Name	Description
Double[,]	hits	sonogram as matrix showing location of oscillation hits.
Int32	minHz	lower freq bound of the acoustic event.
Int32	maxHz	upper freq bound of the acoustic event.
Double	freqBinWidth	the freq scale required by AcousticEvent class.

Returns

Type	Description
Double[]

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RemoveIsolatedOscillations(Double[,])

Removes single lines of hits from Oscillation matrix.

Declaration

public static double[, ] RemoveIsolatedOscillations(double[, ] matrix)

Parameters

Type	Name	Description
Double[,]	matrix	the Oscillation matrix.

Returns

Type	Description
Double[,]	a matrix.