Read this first about USC’s Brain and Creativity Institute using artifical intelligence to determine previously unknown patterns in sounds that effect our brains.
Apply this research to voice and think about what that could mean. Does content matter less than we assume? What if we could monitor the same influences on neurochemistry but not while listening to music but political speeches? I have a suspicion, there is neuroactivity in our brains like what the USC Brain and Creativity Institute is using artificial intelligence to document that corresponds to the sound patterns of a speech and not actual content.
In the past, neuroscientists trying to better understand the impact of music on the body, brain and emotions have analyzed MRI brain scans over very short segments of time—for instance, looking at the brain reacting to two seconds of music. By contrast, in this study, using algorithms to analyze data gathered in the lab, the scientists were able to document how people felt while listening to music over longer periods of time, not only from brain scans, but also combining data from other modes. “Novel multimodal computing approaches help not just illuminate human affective experiences to music at the brain and body level, but in connecting them to how actually individuals feel and articulate their experiences,” said Professor Shrikanth (Shri) Narayanan, study co-author, Niki and C. L. Max Nikias Chair in Engineering and professor of electrical and computer engineering and computer science.
If so that activity could also have some sort of ethnic, religous or geopolitical bias. It could explain alot of what is unexplainable and about government and politics. Oh yeah Im going way of on a tangent totally unrelated to the USC study but they seem to be able to prove by using a.i. that the emotinal memaning of music has to do with patterns humans are unable to recognize. Thats a really big deal that a machine can show us things about ourself that were not previously known. But imagine that applying to all sound not just music. Yep thats possible given the results of their study.
Below are examples of historical speeches and one discussion on a televsion talk show that were deeply influential.
Adolf Hitler at the Krupp factory in 1936 discussing the the sucess of Germany's rapid progress in industrilization and post world war one rearmament and warning of consequences the west would face if it led Germany into a war. Interestingly as a seperate point, in America this video it is widely shared with subtitles that are false. In the part from 2:42 to 3:04 it is commonly quoted / subtitled as saying 'Burn me alive if I am wrong". This is false. Instead what he actually says is, "Pronouce whether you hold my work to be right, whether you believe that I have worked hard, that I have taken your side throughout these years, that I have decently devoted my time to the service of this Volk." 
The powerful "I have a dream speech" is MLK's most quoted and one of my favorites.
I think any objective person would say that Farrakhan's unscripted remarks to being questioned by members of a tv show audience are thoughtful and makes you ( especially if you are white ) think differently about race relations.
Farrakhan's words to a woman that is passionate about "coming together and finding a way" is summed up in his first sentence of his reply "the desire is good but the reality is the total opposite..." After that carefully watch the physical movements he makes and the tone of his replies. His technique is epic. Also note at the 4:28 mark how a woman in the audience states "what scares us is I thinks we hear violence". Not alluding to any specific content (words or phrases) Farrakhan has said. A very odd moment that underscores the psychology of racial division. Farrakhan's first attempt to respond is at the 4:43 mark. Notice the polite insistance and how that is ignored but in his remarks at the 5:12 mark he replies. This response, in my opinion, starting at the 5:54 mark remains the most concise well-spoken articulation of the psychology behind what drives whites to discuss black violence and the underlying reason behind the woman's fear. Guilt of historical violence against people of color, according to Farrakhan. Remember this was unscripted and occured on an afternoon live television show in 1990. Farrakhan's unscripted dialouge remains the standard for a description of the dynamics friving racial division in America.
This is one of my personal favorite speeches of MLK about "the other America". While watching it try to listen to the sound and let your mind pay attention to how he speaks, patterns of intonation and notice how his oration style coordinates with subtle physical movements.
My all time favorite is the innaugeration speech by President John F. Kennedy. Perhaps the bias is the actual content in this case. When JFK says "we have the power now to abolish all forms of human poverty" its painfully obvious 56 years later we have not chosen to exercise that power. What I would like to see is if we can hook up the machines USC is using to people who watch these speeches for the first time. My suspicion is there is a sound pattern present that the actual content doesnt reveal. It would be interesting to compare the brains reactions of the different speeches see if there is a common pattern. Could the change in tone, contrast, and rhythm of sound be more influential than language content ? Just a hunch.