This is interesting (possibly), but does it have any relevance to speech and language, you may ask. Yes most definitely. The ability to hear even the occurrence of some consonants (which occur as sounds in quick succession with vowels) depends on this ability. The principle is the same for distinguishing the order of rapidly presented series of different stimuli.
- Speech, itself, is nothing but sequences of different stimuli (phonemes), and perceiving their order is more than half of the decoding game. If the phonemes are far enough apart in time, you can perceive their order.
Perceiving the order of successive speech sounds depends on their speed of delivery.
- Speech, itself, is nothing but sequences of different stimuli (phonemes), and perceiving their order is half of the decoding game. If the phonemes are far enough apart in time, you can perceive their order.
As they get closer together in time you may still perceive their order...
...but for someone with lesser perceptual processing power...
Some individuals may not be able to perceive the order if they come too fast.
...such as young children with immature neural networks; individuals with brain dysfunction or much older folk like me (with both thinning hair and brain cells) may become confused.
Now we don't know whether the order was CAT or TAC or ACT. In speech, of course, it makes a big difference.
Understanding the order of sounds is also critical for decoding morphological structure and meaning of words.
As you can imagine, the possible combinations increase wildly. Was the word SCAT, TASC, TACS, CATS, etc. etc.? What a confusing task for someone with weak Temporal Resolving Power! Notice, however, that not only the meaning of the word is at risk, but also the meaning that may come through the structure of the bound morphemes!
"Fast Forward" is a computer program that slows down the presentation of consonants.
If a child doesn't perceive the "s" and other bound morphemes on the ends of words, how will he/she learn the principles of grammar, such as plurals and possessives and such? This can impact negatively upon children's language development, reading skills and academic achievement.
The problem of sequencing for some children has been addressed in recent years by a computerized program called "Fast Forward."
This program is produced and marketed by the Scientific Learning Corporation in Berkeley, California. In this program, consonants are prolonged to provide greater time for the child to process and recognize the order of phonemes. The notes below provide respectively, the Company's Web Page, information on Fast Forward, a discussion and a Sample movie.
Games and listening oriented activities will improve Temporal Resolving Power.
Of course, providing listening opportunities for very young children would seem highly advisable to nurture the development of the neurological infra structure that will enable good listening skills for the future.
This can take the general form of multiple daily readings (initially nursery rhymes which provide rhythm, intonation and rhyming. This should be start very early.
I would consider from one week after birth to 14 years, although you can begin to think of broadening the scope from nursery rhymes after two and a half years.
Later, training can take a more structured form like listening centers with games and exercises for children. In the notes are some exercises for school age children.
The localization of a sound depends also on Temporal Resolving Power.
Sound Localization: Because we may not consciously perceive the order, or even the discreteness of two very close successive stimuli, it does not mean that our perceptual system has lost track of the time intervals involved.
We actually are still processing them, but at a different level and in a different way.
Take for example a sound that comes to us from the extreme right side.
The sound wave first reaches our right ear, and then must travel the width of our face to reach the left. There is a brief time interval involved between the stimulation of each ear.
This is maintained as the sound continues in the form of a difference in phase between the input of each ear. But, the time interval is too brief for us to perceive two sounds.
Sound Localization (like stereopsis) requires two normal transducers (ears) .
The brain is still actually receiving two sounds, and processes the time difference between each to produce the illusion of a sound localized in space!
As the sound source moves toward our center (front or rear) the time differential between the ears decreases and the sound appears to move towards the center. We are, at any point in time, only aware of the location of the sound in a single horizontal plane to the right or left.
If it is a brief sound, we can't really ascertain whether its source is to our front or back, or above or below us.
But if the sound persists, we will without realizing it make small adjustments of our head (ears) to sample several different planes and quickly zero in on the sound source.
For the most part it takes two ears to perceive location of the source of a sound.
The sound localization process facilitates figure-ground discrimination.
There are some sophisticated, if not minimal cues for location that do come from a single ear in the form of the resonance created in the Pinna.
This is discussed briefly with some references for anyone who is interested, in the notes below.
There is one more contribution of Temporal Resolving Power, which I would like to point out.
It is the interaction of sound localization with figure-ground discrimination.
You might have noticed, if you have ever taped a lecture and listened to it later, that you were more aware of all the background noises than you were in the actual classroom.
This is because in the classroom, you were able to use sound localization to identify noise sources.
A person with only one good ear will learn language normally, but will have to work harder to understand speech in a noisy environment.
When you listened to the tape, however, the sound source was all from one direction and figure-ground discrimination becomes a more difficult task.
Hence, a person with one good ear may hear sounds as loudly and clearly as anyone else, but will experience more confusion and fatigue in a noisy environment.
The same is true for someone with a hearing aid, which has only one microphone to pick up the sound signals.
4. Auditory Memory:- Memory, of course, is a major component of our neurological armament. It is a massive process that is involved in almost all other cognitive skills. Scientists spend their lives studying it, and still we don't know the basic mechanisms involved. But there is much information we do have, and we will look at some of this later.
Because the speech signal is discursive and transient, memory must retain it until decoding takes place.
But for now we must acknowledge the role of memory specifically in the auditory process. Two things are critical in audition. The auditory stimulus is transient, and the message is discursive. That means the signal is strung out in time. It doesn't hang around long enough for us to experience the entire message in one "sitting," like we can when we observe a picture.
In audition, it remains for the processes of memory to hold on to the pieces of the stimulus that have faded, so that we can deal with them as if we had the whole. Note that I said processes (plural), because memory (like language) is a system of many sub processes.
Of the many memory sub processes, we will mention two for now: Short-Term and Long-Term memory.
Short-Term Memory, is the ability to hold on to the signal for short periods of time--from milliseconds to hours. It is not, however, a single process but a group of sub sub processes: Sensory, Perceptual and Wrote Memory.
Sensory short-term memory, pertains more to the action of the transducer. In many respects it is the counter part of after imagery in the visual but with a different purpose.
Sensory short term memory holds the image from the transducer long enough for us to recognize is structure.
Without the after glow on a radar screen, for example, patterns would be difficult to discern. Sensory short-term memory performs the same purpose. It enables us to recognize sounds patterns, like phonemes.
Perceptual short term memory, relates to our ability to retain strings of words while the brain decodes their phonological, morphological, syntactical, semantic and pragmatic significance. This is truly an amazing process!
People often talk to us in long complicated sentences. The meaning of any sentence can only be obtained from an analysis of the interrelation of all the words taken as a whole.
The sentence must also be analyzed in terms of a sentence that may have occurred earlier in the conversation.
There may be 20 to 50 words in a sentence. We must hold on to the words, extract the meaning, and do it fast enough to be ready to receive the next sentence which comes right on it(tm)s heels, and the next and the next.
What makes it truly amazing is that typically we are limited to approximately 7 bits of information for this short term memory process. We obviously do more by using various organizational strategies.
One important strategies is expectancy. It's interesting that most computers have some of this now in the form of word prediction. You start to type something and the word appears before you finish.
Context and and particularly grammar are important features of expectancy which broaden our input capacity.
For a child (or adult) with severely limited short term memory (say 4 or less bits in information) and with few strategies to rely on, (e.g., poor grammar and/or a dearth of life experiences) decoding an oral sentence can be a significant problem.
A child with a very restricted short-term memory may have difficulty understanding long sentences.
I actually experienced a similar situatiion in Latin II class. I did well with Caesar who came, who saw and who conquered Gaul; and wrote about it in short sentences.
But when I enrolled in Latin III (buoyed by my apparent success in Latin II) I was in for a "Custer's Last Stand" experience. Here we read the works of Cicero who never wrote a short sentence, I am sure, under two pages long. I could never get a complete sentence into my all at once head.
By the time I got to the verb phrase through all the relative clauses etc., I had totally forgotten what the noun phrase had been, not to mention the information that was in all the subordinate and embedded clauses.
My short term memory, I believe, would have to have been 21 bits to get the whole Latin Cicarian sentence.
Ceasar was easier to understand than Cicero (at least for me) because the latter used very long sentences
Granted I had a poor sense of the Latin grammar too, which didn't help my short-term memory.
But, I think I know now why Rome declined. They couldn't understand each other with these long sentences. Just kidding, Latin scholars.
Auditory Perceptual short term memory is often tested in older children by having them repeat a series of numbers of increasing length.
An example from the ITPA is provided in the Notes.
Wrote memory is the short term memory process we use to hold on to information long enough retain lists of items to get from the store, or facts to regurgitate on a test.
We use Wrote Memory to retain information long enough to be processed into Long-Term memory.
Unlike perceptual short term memory which lasts for fractions of a second, this process can last for hours.
It is also useful for holding on to information long enough to convert it into long term memory, but that is a later discussion.
There is much that we can do with our young children to develop perceptual and wrote memory skills.
Reading to the child (the infant too) is a major positive step. Putting TV in the locked closet is another.
Suffice it to say that the brain waves of a person watching the typical TV shows are similar to a person who is asleep. I see limited brain growth there--and a whole lot of wasted time where growth could have taken place..
To be honest, I believe there are a few TV shows which do have merit.
There are many activities that will improve the short-term memory process.
I have already mentioned "Mr. Rogers' Neighborhood". As being excellent for a number of reasons For this show I would let the child in the closet, with the TV, but not until he's three years old and then for no more than 1/2 an hour a day. I would ban all shows with cartoons.
Almost any children's game is beneficial for developing short term memory. Later on chess is outstanding for this purpose.
Theater group play acting is another excellent source of short term memory practice.
Equally important are activities like learning to recite poems, starting with nursery rhymes and continuing, much later on, of course, with things like the Declaration of Independence, and world class poetry.
Not only do these activities provide vocabulary and concepts, but they, more importantly I think, facilitate the neural infra structure for short term memory which will serve the child for a life time. The rule of thumb, here, is to involve the child as
Long Term Memory: Long term memory is, of course, indispensable in any decoding task. Without it, no meaning can be attributed to the percept.
We have discussed problems in this area under Aphasia and Agnosia and we will have more to say about this topic when we examine the cognitive processes of memory.
For now, lets return to the main menu and examine some Behavioral or Learned influences in the perceptual process: Attention and Expectancies.
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