Class EventFilters

Inheritance

Object

EventFilters

Inherited Members

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Namespace: AudioAnalysisTools.Events

Assembly: AudioAnalysisTools.dll

Syntax

public static class EventFilters

Methods

FilterEventsOnComponentCount(List<EventCommon>, Int32)

Removes composite events from a list of EventCommon that contain more than the specfied number of SpectralEvent components.

Declaration

public static List<EventCommon> FilterEventsOnComponentCount(List<EventCommon> events, int maxComponentCount)

Parameters

Type	Name	Description
List<EventCommon>	events
Int32	maxComponentCount

Returns

Type	Description
List<EventCommon>

FilterEventsOnSidebandActivity(List<SpectralEvent>, BaseSonogram, Nullable<Int32>, Nullable<Int32>, Nullable<Double>, Nullable<Double>, TimeSpan)

Removes events from a list of events that contain excessive noise in the lower and/or upper neighbourhood. Excess noise can indicate that this is not a legitimate event. This method measures noise as the average decibel value in the buffer zones above and below the events.

Declaration

public static List<EventCommon> FilterEventsOnSidebandActivity(List<SpectralEvent> events, BaseSonogram spectrogram, int? lowerHertzBuffer, int? upperHertzBuffer, double? thresholdForBackgroundDecibels, double? thresholdForMaxSidebandActivity, TimeSpan segmentStartOffset)

Parameters

Type	Name	Description
List<SpectralEvent>	events	A list of spectral events.
BaseSonogram	spectrogram	A matrix of the spectrogram in which event occurs.
Nullable<Int32>	lowerHertzBuffer	The band width of the required lower buffer. 100-200Hz is often appropriate.
Nullable<Int32>	upperHertzBuffer	The band width of the required upper buffer. 300-500Hz is often appropriate.
Nullable<Double>	thresholdForBackgroundDecibels	The max allowed value for the average decibels value (over all spectrogram cells) in an event's sideband.
Nullable<Double>	thresholdForMaxSidebandActivity	The max allowed value for the decibels value in a sideband timeframe or freq bin.
TimeSpan	segmentStartOffset	Start time of the current recording segment.

Returns

Type	Description
List<EventCommon>	A list of filtered events.

FilterEventsOnSyllableCountAndPeriodicity(List<EventCommon>, Int32, Double, Double)

Removes composite events from a list of EventCommon where the component syllables do not have the correct periodicity.

Declaration

public static List<EventCommon> FilterEventsOnSyllableCountAndPeriodicity(List<EventCommon> events, int maxSyllableCount, double expectedPeriod, double expectedSd)

Parameters

Type	Name	Description
List<EventCommon>	events
Int32	maxSyllableCount
Double	expectedPeriod
Double	expectedSd

Returns

Type	Description
List<EventCommon>

FilterForEventType<T, U>(List<U>)

Declaration

public static (List<T> TargetEvents, List<U> OtherEvents) FilterForEventType<T, U>(this List<U> events)
    where T : EventCommon where U : EventCommon

Parameters

Type	Name	Description
List<U>	events

Returns

Type	Description
(T1, T2)<List<T>, List<U>>

Type Parameters

Name	Description
T
U

FilterLongEvents(List<SpectralEvent>, Double)

Filters list of events to remove long events.

Declaration

public static List<SpectralEvent> FilterLongEvents(List<SpectralEvent> events, double maximumDurationSeconds)

Parameters

Type	Name	Description
List<SpectralEvent>	events
Double	maximumDurationSeconds

Returns

Type	Description
List<SpectralEvent>

FilterOnBandwidth(List<EventCommon>, Double, Double)

Declaration

public static List<EventCommon> FilterOnBandwidth(List<EventCommon> events, double minBandwidth, double maxBandwidth)

Parameters

Type	Name	Description
List<EventCommon>	events
Double	minBandwidth
Double	maxBandwidth

Returns

Type	Description
List<EventCommon>

FilterOnBandwidth(List<EventCommon>, Double, Double, Double)

Filters lists of spectral events based on their bandwidth. Note: The typical sigma threshold would be 2 to 3 sds.

Declaration

public static List<EventCommon> FilterOnBandwidth(List<EventCommon> events, double average, double sd, double sigmaThreshold)

Parameters

Type	Name	Description
List<EventCommon>	events	The list of events.
Double	average	The expected value of the bandwidth.
Double	sd	The standard deviation of the bandwidth.
Double	sigmaThreshold	THe sigma value which determines the max and min thresholds.

Returns

Type	Description
List<EventCommon>	The filtered list of events.

FilterOnDecibelDetectionThreshold(List<EventCommon>, Double)

Filters lists of events based on their DecibelDetectionThreshold.

Declaration

public static List<EventCommon> FilterOnDecibelDetectionThreshold(List<EventCommon> events, double threshold)

Parameters

Type	Name	Description
List<EventCommon>	events	The list of events.
Double	threshold	The Decibel Detection Threshold.

Returns

Type	Description
List<EventCommon>	The filtered list of events.

FilterOnDuration(List<EventCommon>, Double, Double)

Remove events from a list of events whose time duration is either too short or too long.

Declaration

public static List<EventCommon> FilterOnDuration(List<EventCommon> events, double minimumDurationSeconds, double maximumDurationSeconds)

Parameters

Type	Name	Description
List<EventCommon>	events
Double	minimumDurationSeconds
Double	maximumDurationSeconds

Returns

Type	Description
List<EventCommon>

FilterOnDuration(List<EventCommon>, Double, Double, Double)

Filters lists of events based on their duration. Note: The typical sigma threshold would be 2 to 3 sds.

Declaration

public static List<EventCommon> FilterOnDuration(List<EventCommon> events, double average, double sd, double sigmaThreshold)

Parameters

Type	Name	Description
List<EventCommon>	events	The list of events.
Double	average	The expected value of the duration.
Double	sd	The standard deviation of the duration.
Double	sigmaThreshold	THe sigma value which determines the max and min thresholds.

Returns

Type	Description
List<EventCommon>	The filtered list of events.

FilterShortEvents(List<SpectralEvent>, Double)

Filters list of events to remove short events.

Declaration

public static List<SpectralEvent> FilterShortEvents(List<SpectralEvent> events, double minimumDurationSeconds)

Parameters

Type	Name	Description
List<SpectralEvent>	events
Double	minimumDurationSeconds

Returns

Type	Description
List<SpectralEvent>

GetLowerEventSideband(SpectralEvent, Double[,], Double, Int32, UnitConverters)

Returns the matrix of neighbourhood values below an event.

Declaration

public static double[, ] GetLowerEventSideband(SpectralEvent ev, double[, ] spectrogramData, double bufferHertz, int gap, UnitConverters converter)

Parameters

Type	Name	Description
SpectralEvent	ev	The event.
Double[,]	spectrogramData	The spectrogram data as matrix with origin top/left.
Double	bufferHertz	THe bandwidth of the buffer zone in Hertz.
Int32	gap
UnitConverters	converter	A converter to convert seconds/Hertz to frames/bins.

Returns

Type	Description
Double[,]	The sideband as a matrix.

GetPeriodicity(Boolean[], Double)

Declaration

public static (int Count, double AveragePeriod, double SdPeriod) GetPeriodicity(bool[] temporalFootprint, double timeScale)

Parameters

Type	Name	Description
Boolean[]	temporalFootprint
Double	timeScale

Returns

Type	Description
(T1, T2, T3)<Int32, Double, Double>

GetTemporalFootprint(EventCommon)

Declaration

public static (bool[] TemporalFootprint, double TimeScale) GetTemporalFootprint(EventCommon compositeEvent)

Parameters

Type	Name	Description
EventCommon	compositeEvent

Returns

Type	Description
(T1, T2)<Boolean[], Double>

GetUpperEventSideband(SpectralEvent, Double[,], Double, Int32, UnitConverters)

Returns the matrix of neighbourhood values above an event.

Declaration

public static double[, ] GetUpperEventSideband(SpectralEvent ev, double[, ] spectrogramData, double bufferHertz, int gap, UnitConverters converter)

Parameters

Type	Name	Description
SpectralEvent	ev	The event.
Double[,]	spectrogramData	The spectrogram data as matrix with origin top/left.
Double	bufferHertz	The bandwidth of the buffer zone in Hertz.
Int32	gap
UnitConverters	converter	A converter to convert seconds/Hertz to frames/bins.

Returns

Type	Description
Double[,]	The neighbourhood as a matrix.

IsSidebandActivityBelowThreshold(Double[,], String, Nullable<Double>, Nullable<Double>)

This method determines the acoustic activity in a portion of a spectrogram. The passed matrix represents the sideband of an acoustic event. The sideband is subject to two tests:. Test 1: Tests whether the average or background decibel value in the sideband is below the user supplied threshold? Test 2: This test covers the possibility that there is much acoustic activity concentrated in one or two freq bins or time frames. Therefore, also require that there be at most one sideband bin or frame containing acoustic activity greater than the supplied decibel threshold.

Declaration

public static bool IsSidebandActivityBelowThreshold(double[, ] sidebandMatrix, string side, double? thresholdForBackgroundDecibels, double? thresholdForActivityDecibels)

Parameters

Type	Name	Description
Double[,]	sidebandMatrix	A matrix that represents a portion of spectrogram which is actually the sideband of an acoustic event.
String	side
Nullable<Double>	thresholdForBackgroundDecibels	Decibel threshold for the background test.
Nullable<Double>	thresholdForActivityDecibels	Decibel threshold for the activity test.

Returns

Type	Description
Boolean	A boolean determining whether the sideband is accepoted or rejected.