Physical Measurements - instruments to quantify some aspect of the phenomena of interest. Acoustics Phonetics is the study of the acoustic characteristics of speech. The Inner Ear B. Threshold of Audibility Ear not equally sensitive to all frequencies. Least sensitive at low and really high frequencies. Distinctive Features a very popular way of distinguishing among phonemes.
Distinctive Features seem to have perceptual relevance.
Distinctive Features are properties of the message. Distinctive Features do not explain speech perception however. F. Articulatory Reference Theory Speech is perceived in reference to the way in which it is produced. Generative process produces a change in the internally produced model so as to reduce the error signal to a minimum. Higher stages of processing may also be required.