.
扬声器测试声音（15-20000赫兹） – 60分钟（一小时）线性幅度，全范围，低音，介质和高音 – 视频光谱和高质量音频.
For more great videos, please subscribe to this YouTube channel or our Facebook page: Relaxing and useful sounds, noises and videos (https://www.facebook.com/relaxingsoundsandvideos). —–
Do you want to start painting like a pro? Free video painting tutorials on this channel (https://www.youtube.com/user/liyndahandmade/videos). Subscribe to receive weekly video tutorials.
—–
DIY ideas from all fields and multiple languages on this channel (https://www.youtube.com/channel/UCi7NEe3ppsYLbIDgwOB3_2A/videos). Subscribe to receive free video tutorials and ideas. .