Several examples of this phoneme disconnect are outlined in Fry’s “Homo Loquens” book:
1) “English uses the difference between /s/ and /sh/ as a way of distinguishing words, so that we can find pairs like save and shave, sin and shin, mass and mash. The phonemic system of Dutch or of Spanish or of a number of Indian languages does not include this distinction and as a consequence native speakers of these languages are quite unable to perceive the difference in English unless they have made a special effort to learn to do so.” (page 15)
2) “Another example is to be found in the final sounds of win and wing which are indistinguishable to a native Italian speaker…. his language [also] contains no pair of words differentiated solely by the presence of either /n/ or /ng/.” (page 15)
3) “The phonemic system in quite a number of Indian languages includes as many as six different t sounds which are all but indistinguishable to the English ear. Among them is a pair which differ from each other in the same way as the t sounds in the two English words tar and star, but this is not a difference that has any function in the English system and we are therefore unaware of its existence.” (pages 15-16)
4) “…the fact that Japanese speakers cannot detect the difference between /r/ and /l/ sounds and cannot make the distinction when talking English. A rather endearing example is that of the Japanese who when making an after-dinner speech in English confessed that he was rather nervous and ‘had butterfries in his stomach’.” (page 72)
It is apparent that from the perspective of the person speaking there is no difference between the distinct phoneme sounds. As a consequence he/she feels phoneme sounds can be used interchangeably.
This same phenomenon can be seen in the early language developmental stages of children speaking their native language. During this developmental stage children cultivate the ability to distinguish and enunciate various phonemes.
Often a child uses dissimilar phonemes interchangeably without distinction. In these situations the child exclusively employs the more easily pronounced phoneme. When the child then hears the phoneme pronounced correctly, they typically insist that this is exactly how they had said it.
At this point they have not developed the ability to distinguish between two dissimilar phonemes. This process is much the same as that of learning a foreign language.
Once upon walking through a wooded area with a child of three, he informed me that there was a really big wock (rock) off to the right. Jokingly I responded, “Yes, that is a really big wock.” At which point young William informed me that obviously I had difficulty with the pronunciation of that word, for I had said it incorrectly.
I have also heard the story of a child who requested that an individual “keep quiet because the baby is sweeping (sleeping).” He replied, “Oh, the baby is sweeping?” She looked at him puzzled and stated emphatically, “Not sweeping: sweeping!”
This language development pattern serves in some form as reinforcement of the fact that the phoneme system is complex. It is learned gradually and mastered through every day usage. The typical inability to have multiple primary languages results in a situation where phoneme variations in languages are difficult to interpret due to their abundance.
“People who have a common language have learned to adopt a particular system and moving to another language means acquiring a new and additional system of phonemic organization.” (“Homo Loquens”, page 16)
This can be difficult. It is also unclear whether or not mastering phonemic pronunciation in a language guarantees phonemic comprehension. Perhaps differentiating spoken phonemes is more difficult than actually speaking them. This hypothesis is somewhat supported by Professor Campbell’s experience with fluent non-native English speakers.
There are additional criteria that lend themselves to word comprehension. Intonation and rhythm can dramatically affect the meaning that is being conveyed by the speaker.
“The various intonations that can be given to a sentence are themselves part of the grammar of the spoken language and the information about the intonation system is another component in the linguistic knowledge stored by the brain.” (Homo Loquens, page 16)