Alvin Liberman - Research

Research

Liberman was one of the first to conduct research and experimental studies in the field of speech development and linguistics. Through his research he aimed to gain a thorough understanding of the importance and purpose of speech in the act of reading and the process of learning to read. Some of his profound investigations were made during his time at Haskins Laboratories where he worked as a research scientist trying to investigate the relationships between speech and acoustics. From his research he came up with the idea that we hear spoken words much differently than sounds. It was evident to Liberman that speech, the speed at which someone says something in particular, is connected to the word's amount of syllables, or in other terms its "acoustic complexity" (Whalen, 2000). When it comes to speech and conversation, it "does not come to us as a series of individual words; we must extract the words from a stream of speech." Liberman and his colleagues were training the blind to read using a reading machine that would replace each letter of the alphabet with a specific sound. However, he and his colleagues found that the replacement of the sounds for each distinct letter of the alphabet did not help with the blind to learn to read or pronounce the letters fluently. After long investigations of why this was, Liberman established that speech was not as simple as an acoustic alphabet. Therefore, speech signals are very distinct from acoustic alphabet (Fowler, 2001). These investigations showed that speech perception is different from perception of other acoustic signals, and convinced Liberman that speech perception is the result of the human biological adaptations to language. Human listeners are able to decode the repetitive variable signal of running speech and to translate it into phonemic components. This is also known as the "motor theory of speech perception".

In one of his articles, Liberman mentioned speech production is easy to create as it relies on the "conscious awareness of phonological structure". He disagreed with "horizontal theory" because it would imply that the "advantage of ease" would be dependent upon reading and writing, not speech. Liberman also argued that reading alphabets is not important to speech until one learns the phonological pattern of speech. He made mention that speech itself is not only attributed to biological evolution, rather it is also species specific.

Liberman also examined why reading is more difficult than speech perception. He attributed this greater difficulty to the human biological adaptation to speech. Liberman discovered that children who fail to learn to read on schedule lack phonemic awareness. Phonemic awareness is an awareness that word forms breaks down into individual parts. This is because they cannot appreciate the alphabetic principle.