On November 24, video of the Laquan McDonald shooting was released by the Chicago police department – video that did not have audio. Subsequently, a video of the same incident, allegedly with audio, was posted on YouTube. I was asked to take a look at the video and offer my professional opinion as to the authenticity of the audio portion.
During my investigation of the YouTube video titled “Is this the audio? Chicago Police dashcam video of Laquan McDonald shooting”, I discovered several anomalies and inconsistencies using Time Domain Analysis, Frequency Domain Analysis, and Critical Listening Skills. I have outlined these anomalies and inconsistencies.
- In the image above, the Spectrogram shows the cutoff frequency of the gunshots well above the cutoff frequency of the noise floor, or background noise (radio chatter & siren). A closer look at the difference in frequency content between the gunshots and background noise is displayed in the image below:
- The cutoff frequency of the audio content from the YouTube video titled “Is this the audio? Chicago Police dashcam video of Laquan McDonald shooting” is around 16 kHz. This is displayed in the image below:
Based on my experience, audio recorded evidence produced from law enforcement vehicles contain a cutoff frequency of 4kHz. I have examined the frequency analysis of the audio recorded in the original video evidence with lack of radio communication & officer dialogue. The cutoff frequency analysis of the original video evidence is displayed below:
Based on my testing and analysis, I can confidently say that the audio portion of this video has been manufactured and added to the video. For what purpose? Only the ‘creator’ of the video can answer that.
- The original video released by Chicago Police contains recorded audio content of crosstalk, and alternator or engine noise (see above image). The noises that are audible within the original video recording are low in amplitude but can be heard with a significant increase in volume. Because this digital recorder recorded an audio track, it is my opinion that it was functional and had the ability to record sound. Because of the lack of officer dialogue, radio chatter, we believe the lack of these sounds was due to the following reasons:
- The on-person lavalier microphones within the vehicle were muted
- The on-person lavalier microphones within the vehicle were disconnected
- The on-person lavalier microphones within the vehicle were deactivated
- The gunshots, and radio chatter heard throughout the YouTube video titled “Is this the audio? Chicago Police dashcam video of Laquan McDonald shooting” are duplicated, equalized and are not genuine or authentic. Previously in this blog I discussed the inconsistency between the cutoff frequency of the gunshots and cutoff frequency of the background noise within the audio content. In addition, the audible fingerprint of the gunshots within the Spectrogram has a distinct shape, size, and intensity that are consistent with duplication or repetition. The frequency decay of the gunshot, timbre or sound of the gunshot, as well as duration of the sound are almost identical. The gunshots are displayed in the image below:
The radio chatter sample at timecode 0:04.387 (MM:SS:MS) is an exact duplicate of the radio chatter sample 0:03.000 (MM:SS:MS). The conversation being spoken is identical. The difference between the two is that the duplicate has been processed using equalization to deceive the listener into believing it is additional radio conversation.
This video claiming to have genuine audio is indeed a fake.
Tags: Laquan McDonald