The theme: Aspects of phonetics and methods of investigations Transcription. Plan:I. Aspects of phonetics: 1. The articulatory aspect 2.The acoustic (physical) aspect 3.The perceptual (auditory) aspect 4. The phonological aspect. The principal methods of Investigation used in phonetics are:The direct observation method. The linguistic method. The experimental method. The simplest and most readily-available method of Investigation is the method of direct observation. This method consists in observing the movements and positions of one's own or other peoples organs of speech in pronouncing various speech sounds as well as in analyzing one's own sensations (muscle sense) during the articulation of speech sounds and in comparing them with the resultant auditory impressions (phonetic analysis by ear, sight, muscular sensation). Investigation by means of this method can be effective only if the persons, implying it, have been specially trained to observe and distinguish the slightest variations in sound quality.