title: What features does an android device returing true to PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND and PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND have
body: <p>I was checking the Android API documentation and inside the AudioManager page I found the following properties.  </p>
  
  <pre><code>PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND (Added in API level 23)
  
  String PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND
  
  Used as a key for getProperty(String) to determine if the default microphone audio source supports near-ultrasound frequencies (range of 18 - 21 kHz).
  
  
  PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND (Added in API level 23)
  
  String PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND
  
  Used as a key for getProperty(String) to determine if the default speaker audio path supports near-ultrasound frequencies (range of 18 - 21 kHz).
  </code></pre>
  
  <p>I was wondering what is the technical meaning of "supports near-ultrasound frequencies" </p>