Android設備返回true屬性爲PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND和PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND有什麼功能

Question

我正在檢查Android API文檔，並在AudioManager頁面內找到以下屬性。

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). 

我想知道什麼是技術意義「支持近超聲頻率」

Answer 1

我發現它的Android 7.0兼容性定義文件

7.8.3裏面。近超聲

近超聲音頻是18.5 kHz至20 kHz頻段。設備實現必須經由AudioManager.getProperty API正確報告近超聲音頻能力的支持如下：

If PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND is "true", then the following requirements must be met by the VOICE_RECOGNITION and UNPROCESSED audio sources: 
    The microphone's mean power response in the 18.5 kHz to 20 kHz band MUST be no more than 15 dB below the response at 2 kHz. 
    The microphone's unweighted signal to noise ratio over 18.5 kHz to 20 kHz for a 19 kHz tone at -26 dBFS MUST be no lower than 50 dB. 
If PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND is "true", then the speaker's mean response in 18.5 kHz - 20 kHz MUST be no lower than 40 dB below the response at 2 kHz. 

Answer 2

支持近超聲頻率意味着麥克風可以在18的範圍記錄聲音 - 21千赫（如從你引用的文件中引用。）