Here is an excerpt from a National Transportation Safety Board Aircraft Accident Report…
Research has shown that fundamental frequency (pitch) can convey information
about a speaker’s psychological stress.
With regard to fundamental frequency, the Safety Board used the following guidelines from two previous accident investigations to evaluate the approximate degree of psychological stress experienced by a pilot and its effect on performance:
• An increase in fundamental frequency by about 30 percent (compared with that individual’s speech in a relaxed condition) is characteristic of stage 1 level of stress, which could result in the speaker’s focused attention and improved
• An increase in fundamental frequency by about 50 to 150 percent is
characteristic of stage 2 level of stress, which could result in the speaker’s
performance being hasty and abbreviated and thus degraded; however, the
speaker’s performance would not likely display gross mistakes.
• An increase in fundamental frequency by about 100 to 200 percent is
characteristic of stage 3 level of stress, or panic, which would likely result in
the speaker’s inability to think or function logically or productively.