Eye contact and voice
You can tell if someone is being sarcastic when speaking to them, because they convey their message in a flat, dull, tone- usually a contrast to the actual words they're saying. This is why miscommunication works in texting, because there's no way to emphasise certain words.
Voice can comfort others, like when a mother is talking to their baby, as opposed to a boss talking to his worker. This is called your tone, the way you use your voice to comfort or to discipline others.
Your pitch usually shows your age and gender. If your voice is more high pitched, you're more likely to be young or female. If your voice is more low pitched, you're more likely to be older or male.
People often associate your voice with your confidence and freedom-- "speaking your voice" is a way to show your individuality and freedom while speaking without fear is seen as confidence.
When voices are recorded, they look like this.
The man is speaking (the picture shows his voice as an audiowave).
This represents what nonverbal aspects there are in the voice.
The eyes can often speak for how a person feels and how long they look at you. If you're mad a someone, you'll tend to stare at them for a while, pinning your aggression on them.
Eye contact can be seen as confidence, like holding your gaze with someone who is economically and socially better than you. Even paying attention in class is seen as a good virtue.
Eyes, and direct eye contact is seen as identity and intimidation. In the horror genre, a lack of eyes or too many eyes is perceived as creepy, and holding a stare for too long is seen as intimidating or socially awkward.
Eyes are also seen as a "window to the soul". Typically in mythology, one eye is represented with knowledge. Several creatures from mythology have one eye, and spiders are often seen as a common fear, have many eyes.
Having someone direct all of their attention on you for a constant amount of time gets awkward after a while.
Staying attentive and making eye contect is two ways to help secure a job.
The two men in the photo are about to fight, so this contact is intense.