android 设备返回 true 到 PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND 和 PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND 有哪些功能

Question

我正在检查 Android API 文档，并在 AudioManager 页面中找到了以下属性。

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“支持近超声频率”的技术含义是什么

Answer 1

我在 Android 7.0 兼容性定义文档中找到了它

7.8.3。近超声

近超声音频是 18.5 kHz 至 20 kHz 频段。设备实现必须通过 AudioManager.getProperty API 正确报告对近超声音频功能的支持，如下所示：

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

支持近超声频率意味着麦克风可以录制 18 - 21 kHz 范围内的声音（如您引用的文档中所引用的那样。）