Acoustic characteristics are determined by position and timing of articulators. Place of articulation is cued by frequency changes over time. These changes occur in the high-frequency region. In the case of stop consonants, these changes are known as F2 transitions. The back stops are represented by falling transitions while the front stops are represented by rising transitions.
Manner of articulation is cued by both frequency and temporal changes.
Voicing is cued by broad spectral energy and some temporal information. There is a relative intense cue in the low frequencies because of the fundamental frequency. The long term speech spectrum represents the average of speech over time. Recognizing that a change has occurred in frequency, intensity, or temporal information. That is, heartrate or sucking, is measured in response to an ongoing stimulus, and over time the sound is less interesting and a decline in rate is observed.