At about 20.6 seconds, the file gives you enough room to choose a full knocking sequence or trim a tighter burst. Its firm taps can cut through speech, so lower the level when layering it beneath dialogue. Download the MP3 to keep a local copy for offline playback, then select the cleanest section for a ringtone or notification tone if your phone allows custom audio. Check the result through headphones and speakers, since loud background music can mask the knocks while quiet scenes can make them feel too abrupt.