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An omnidirectional microphone has a response which is equal to one in all nonbaffled directions. The phased.OmnidirectionalMicrophoneElement object enables you to model an omnidirectional microphone. When you use this object, you must specify these aspects of the microphone:
Operating frequency range of the microphone
Whether the response of the microphone is baffled at azimuth angles outside the interval [–90,90]
Construct an omnidirectional microphone element using the human audible frequency range of 20 to 20,000 Hz. Baffle the microphone response for azimuth angles outside of +/– 90 degrees. Plot the microphone's power response at 1000 Hz in polar form.
hmic = phased.OmnidirectionalMicrophoneElement(... 'BackBaffled',true,'FrequencyRange',[20 20e3]); plotResponse(hmic,1e3,'RespCut','3D','Format','Polar',... 'Unit','pow');
In many applications, you sometimes need to examine the microphone's directionality, or polar pattern. To do so, set the RespCut argument of plotResponse to one of the 2-D options and set the Format argument to 'Polar'. The 2-D options for the cut of the response are 'Az' (default), and 'El'.
% Using the default azimuth cut figure; plotResponse(hmic,1e3,'Format','Polar');
Use step to obtain the microphone's magnitude response at the specified azimuth angles and frequencies. The elevation angles are 0 degrees. Note the response is one at all azimuth angles and frequencies as expected.
freq = 100:250:1e3; ang = -90:30:90; micresp = step(hmic,freq,ang)