That which makes the voice truly interesting to listen to is color; the life, animation, the emotion you express in speaking.  Among the characteristics that make for colorful speaking are speed, force, pacing, pause, inflection, emphasis, and tone.   All are important, but the one, in particular, that deals specifically with the mood, attitude, or emotion you convey in relationship to your subject or topic is tone.

If you were to give a talk about the techniques used in working with children who have learning disabilities, your tone of voice should be hopeful, positive.  On the other hand, were you to describe the outcome of a recent school shooting, your tone is not going to be positive but instead negative because the situation is not only dangerous and lethal, it is also something that we cannot seem to stop.

Years ago when I was working with journalism students in voice and delivery, I found many of them reading their broadcasts with the same tone of voice for each topic.  Announcing the winner of the Super Bowl is going to have a different tone than a story about the discovery of a dog-fighting business.  Whereas the former probably would be given in an uplifting and joyous tone, the latter story would sound grave and serious.  Your attitude towards your topic as well as your emotional involvement with the topic should affect your tone.

If you would like learn more about your tone, try the exercise below:  record yourself reading the two examples and then playback and study the recording.

Action-filled-- Instinctively the cop groped for the edge of the aisle seat in order to get to the stage, but before he could move, the lights went back on briefly  followed by another electrifying clap of thunder which brought even more turmoil and a total blackout.

Contemplative-- It is fascinating to read about or watch animals in the wild.  They nurture their young, tending to their needs much as we nurture and tend to the needs of our young.  While there are numerous similarities in the raising of our young by both animals and man, there is a difference.  Animals in the wild are taught to kill for survival whereas man kills survival.

Was there a difference in your tone between the two readings?  Good tone of voice would involve an urgency and excitement in the first reading versus a compassionate, more thoughtful tone in the second.

Not only will tone be heard in your voice but it will also be seen in your facial expression as well as in your body language.

Learn to adjust your tone according to your topic because tone sets the mood for what you want your audience to hear.