嘴皮发出的奇妙声响 Wonderful sound of mouth

某日午睡醒了之后发现嘴皮能发出奇怪的口哨声，就用手机录下来了。有一个频率很高的片段，看了下频谱，基频是 3—4 khz，绝了。手机录的，原始格式是 22khz，音质很渣。详见 kqh.me/recording/

When I woke up one afternoon, I found that my mouth could make a strange whistle, and I recorded it on my mobile phone. There is a very high frequency segment. The spectrum shows the fundamental frequency is 3-4 khz. The original format of the mobile phone is 22khz, and the sound quality is terrible.