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phased.CustomMicrophoneElement System object

Package: phased

Custom microphone

Description

The CustomMicrophoneElement object creates a custom microphone element.

To compute the response of the microphone element for specified directions:

  1. Define and set up your custom microphone element. See Construction.

  2. Call step to compute the response according to the properties of phased.CustomMicrophoneElement. The behavior of step is specific to each object in the toolbox.

Construction

H = phased.CustomMicrophoneElement creates a custom microphone system object, H, that models a custom microphone element.

H = phased.CustomMicrophoneElement(Name,Value) creates a custom microphone object, H, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

Properties

FrequencyVector

Operating frequency vector

Specify the frequencies in hertz where the frequency responses of element are measured as a vector. The elements of the vector must be increasing. The microphone element has no response outside the specified frequency range.

Default: [0 1e20]

FrequencyResponse

Frequency responses

Specify the frequency responses in decibels measured at the frequencies defined in the FrequencyVector property as a row vector. The length of the vector must equal the length of the frequency vector specified in the FrequencyVector property.

Default: [0 0]

PolarPatternFrequencies

Polar pattern measuring frequencies

Specify the measuring frequencies in hertz of the polar patterns as a row vector of length M. The measuring frequencies must be within the frequency range specified in the FrequencyVector property.

Default: 1e3

PolarPatternAngles

Polar pattern measuring angles

Specify the measuring angles in degrees of the polar patterns as a row vector of length N. The angles are measured from the central pickup axis of the microphone, and must be between –180 and 180, inclusive.

Default: [-180:180]

PolarPattern

Polar pattern

Specify the polar patterns of the microphone element as an M-by-N matrix. M is the number of measuring frequencies specified in the PolarPatternFrequencies property. N is the number of measuring angles specified in the PolarPatternAngles property. Each row of the matrix represents the magnitude of the polar pattern (in decibels) measured at the corresponding frequency specified in the PolarPatternFrequencies property and corresponding angles specified in the PolarPatternAngles property. The pattern is assumed to be measured in the azimuth plane where the elevation angle is 0 and where the central pickup axis is assumed to be 0 degrees azimuth and 0 degrees elevation. The polar pattern is assumed to be symmetric around the central axis and therefore the microphone's response pattern in 3-D space can be constructed from the polar pattern.

Default: An omnidirectional pattern with 0 dB response everywhere

Methods

cloneCreate omnidirectional microphone object with same property values
getNumInputsNumber of expected inputs to step method
getNumOutputsNumber of outputs from step method
isLockedLocked status for input attributes and nontunable properties
isPolarizationCapablePolarization capability
plotResponsePlot response pattern of microphone
releaseAllow property value and input characteristics changes
stepOutput response of microphone

Examples

Create a custom Cardioid microphone, and calculate that microphone's response at response at 500, 1500, and 2000 Hz in the directions [0;0] and [40;50].

h = phased.CustomMicrophoneElement;
h.PolarPatternFrequencies = [500 1000];
h.PolarPattern = mag2db([...
    0.5+0.5*cosd(h.PolarPatternAngles);...
    0.6+0.4*cosd(h.PolarPatternAngles)]);
resp = step(h,[500 1500 2000],[0 0;40 50]');
plotResponse(h,500,'RespCut','Az','Format','Polar');

Algorithms

The total response of a custom microphone element is a combination of its frequency response and spatial response. phased.CustomMicrophoneElement calculates both responses using nearest neighbor interpolation and then multiplies them to form the total response. When the PolarPatternFrequencies property value is nonscalar, the object specifies multiple polar patterns. In this case, the interpolation uses the polar pattern that is measured closest to the specified frequency.

See Also

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