At first acoustics attributed ...

At first acoustics attributed to the different sounds only a limited number of characteristic features.
 Roman Jakobson

Quotes from the same author

Acoustic phonetics, which is developing and increasing in richness very rapidly, already enables us to solve many of the mysteries of sound, mysteries which motor phonetics could not even begin to solve.
 Roman Jakobson
Linguistic sounds, considered as external, physical phenomena have two aspects, the motor and the acoustic.
 Roman Jakobson
Remember that the pharynx is at a crossroads from which leads off, at the top, the passage to the mouth cavity and the passage to the nasal cavity, and below, the passage to the larynx.
 Roman Jakobson