Starting Characteristics of Speech Sounds
R. O. Drew, Edward W. Kellogg · The Journal of the Acoustical Society of America · 1940
In view of its bearing on the design of ground noise reduction systems, a study was undertaken, to determine how sudden or rapid are the increases in amplitude of the speech sounds that must be recorded in dialogue. A large number of oscillograms were taken, a number of which are reproduced herewith. The most important observation is that the human voice can start several of the vowel sounds in such a way that the first wave is from 40 to 80 percent of the final amplitude, or in other words with a suddenness comparable to that of keying an oscillator, but this is rare, being for all practical purposes confined to a few of the more open vowel sounds, when not preceded by any consonant, and only true of certain individuals, and depending on the manner of releasing the breath. Progressive build-up at rates which would carry the modulation from zero to 100 percent in 0.05 second are frequent, while the great majority of syllables start more gradually than this.