Archive for July 12th, 2009
Psycho-physical methods in HF
Posted by: adonis49 on: July 12, 2009
Article 37
“Psycho-physical methods in HF”
In the 19th century, a few physiology and neurophysiology scientists such as Gustav Theodor Fechner (1860), von Helmholtz, and Weber endeavored to study the functional relations between body and mind which resulted in the development of controlled experiments for reaching common reference points that would relate the psychological feelings of the senses to their corresponding physical measurements. For example, the relationship of the perception of brightness and color versus amplitude and frequency of radiant energy waves or the feelings of loudness and pitch versus amplitude and frequency of mechanical or sound waves.
Fechner demonstrated that the biology of the human records the variations of the environment by attenuating them to logarithmic values. The sound intensity of ten violins in an orchestra is actually heard as one violin; if the conductor wished the audience to hear the sound of ten violins then he will have to increase the number of violinists to one hundred. If the cord of an instrument vibrates at 80 Hz, then if the cord is pinched in the middle it will vibrate at 160 Hz, at 1/4 it will vibrate at 320 Hz and so on. Thus, the pitch sensation and identification of octaves in a sound is attenuated logarithmically too. As the physical stimulant increases geometrically, the biology of the human senses the increase as an arithmetic progression.
Weber discovered that the ratio of the differential threshold to the initial stimulant for the subject to sense a modification in the variation is a constant. In the case of the pitch the constant is 1.0594; so that for a frequency of 440 Hz (the first La in the octave) then the next frequency to be differentiated would be 440 * 1.0594 = 466 Hz, the next frequency to be sensed would be 494 Hz. The absolute threshold or the minimal excitation to hear a pitch is 3 Hz.
The psychophysical method have been applied extensively in telephone, TV, radar, illuminating, sound, and geophysical industries who wanted to provide the end users with a satisfactory psychological comfort level without undue expenditure on top notch physical circuitry or infrastructures that would not add to the requisite human performance and capabilities.
Recently, there have been attempts to adapt this method to studying complex cognitive concepts such as attitudes, mental abilities, reliable speech quality, and naturalness of voice in telephone by measuring these concepts.
The measurements of interest are: the absolute thresholds (limens) that mark the boundary between sensation and no sensation, the differential thresholds or the smallest detectable change in sensation corresponding to the amount of changes in the physical stimuli, and the equality effects values in sensations produced by two different kinds of physical stimuli like when you filter a green color to make feel as bright as a red color. Subsequently, whenever stimulus is mentioned it means a physical value and response of a subject refers to his answer for a psychological sensation.
The psychophysical method capitalizes on the capabilities of human such as first, being excellent in simple detection tasks or null indicator or whether a sensation exist or not; second being good in differentiating the direction of strength of a sensation such as bigger or smaller than a standard, but he is bad is evaluating whether a sensation is twice or three times stronger, and he is worst as a meter for exact measurements; third human is more accurate in feeling than when relying on his mind and that is why a subject is forced to make a choice between two stimuli rather than responding that the sensation is equally strong.
For example, it is harder to hear speech in a noisy environment than in a quiet one; the problem is to investigate how loud should a person raise his voice in order to be heard in a noisy room?
The development of this method generated three basic procedures for measuring the equivalence between psychological sensations and the physical parameters which are: Procedure of adjustment or average error, procedure of limits or just-noticeable difference, and the procedure of constants which is the most accurate and widely applicable. Consequently, we will focus on the third procedure in the subsequent sections.
The procedures of adjustment and of limits are slightly different but generally the experimenter shows the subject two series of stimuli; the first series starts with a stimulus well above threshold and the subsequent values diminish by small and equal steps; the second series starts well below threshold and values are increased in equal amounts. The final responses of the subject are averaged whether the response is an indicator of a sensation or expressing direction of strength such as more than, equal, or less than. The experimenter either takes control of varying the stimuli or he may allow the subject to control the stimuli until he reaches a definite sensation response.
The procedure of constants starts with the experimenter performing an exploratory study to determine the upper and lowest thresholds and then selects between 4 to 7 stimuli spanning the range of sensations. These selected stimuli are everytime randomized when presented more than 50 times to the same subject. If equality or differential thresholds are being measured then a standard value is compared to the subject responses. Usually, the more intense the stimulus the higher the percentage of correct identification and the choice of threshold criterion vary between 100% correct answers and 50% which basically represents chance happening depending on the behavior of responses or the graph trend and shape; the stimulus value adopted corresponds frequently to a threshold criterion of 75% correct.
An example is in order. A telephone company is planning to provide TV viewers with signals transmission that give sharp images without the need to invest in expensive top notch circuit infrastructure. The bandwidth for transmission should be more than adequate for a satisfactory picture; a bandwidth of 4 megacycles transmits blurred images while 10 megacycles is more than excellent. A cheaper simulator is achieved by using an optical defocusing of movement of the projection lens corresponding for the range of zero to 10 mils. An observer views a standard scenes compared to an identical but partly blurred scene. The amounts of blurring are set up in steps of 2 mils and the subjects are forced to guess which scene is the sharper. By selecting a threshold criterion of 75% correctly guessed the company was able to decide on an effective bandwidth of less than 7 megacycles that provide an excellent sharpness psychologically and save on irrelevant costly hardware.
There are many pitfalls for inexperienced investigators conducting psychophysical experiments and many of these problems are the results of systematic biases such as: 1. Observers tend to quickly receive cues from the control devices they are handling and their responses become biased; 2. the space order of the standard and variable stimuli can be a source for error biases, for example, it is well known that a vertical line looks longer than an identical horizontal line; 3. the second of two equal stimuli is judged louder or brighter than the first; 4. a series of “yes” responses for example encourages a subject to persist in the same kind of response, thus the experimenter should vary the direction of responses; 5. observers tend to get cues from the experimenter through his voice, gestures, or instructions. Most of these errors can be counterbalanced when the order of stimuli presented is randomized at each trial.
The psychophysical method is being used in the study of sensory performance of non-human species as well.
B made me walk on air
Posted by: adonis49 on: July 12, 2009
I Should Have Told Barbara
The sister of Barbara insisted that I get in touch with her on my trip to Los Angeles.
I were in the USA for less than 11 months, my first ever trip outside my country. The International Office at the University of Oklahoma arranged a trip for one week to California, for some of us new international students. We were to meet American families in this exchange program. I did not care meeting any American families for the time being, but I needed to get away in my second summer and wanted to see California. I was 27 of age and had never tasted a cigarette yet.
The International student advisor knew about my Near Eastern origin. The program matched me with an old Jewish couple in Pasadena. The husband was very helpful and friendly but his wife gave me the impression that she agreed reluctantly to join the program.
The house was large with an unkempt garden. The interior looked old, traditional, very gloomy, and smelling like it was never aerated and reeking of old people. It is a crime to surprise youths with living among old people without prior preparations and warnings. We should be reminded that elder people are great people, still very much living humans, who could be funny, and could be functional…
We had a general gathering the first day with all the families and various students. Then we were given the daily program of places to see and whatever. We were to see Disney Land the next day for free. I declined the invitation: Disney Land is for kids. I remember that I had another chance to visit Disney for free, two years later. I again declined. Disney was still just for kids.
Many years later, I discovered that everybody liked to see Disney, including kids.
I never saw Disney in California, but the smaller version in Orlando with my nephews.
My little nephews and nieces, then 5 in total, loved Disney but less than I did.
My old host drove me for two hours to the meeting place with Barbara.
He drove two hours to pick me up three hours later. I still can visualize Barbra after thirty years, coming toward me in white shirt, long brown skirt reaching a little below her knees, almost touching her long brown cowboy boots. Her boots must have added several inches to her stature.
Barbara is not tall, but the vision is always of a tall and grand lady. She appeared taller than me but my pride increased correspondingly, being by her side. Her maybe dyed long blonde-brown hair was raised over her beautiful head. She was glamour incarnate. She hugged me and made me feel I was a dear friend, of long time, whom she missed badly.
She spoke with effusion and earnestness. She wanted to know all that is to know, instantly, about how her sister is doing, what about her sister’s boyfriend who was my friend, about their relationship, about Oklahoma her home State, about everything but me.
I was glad that I was not the object of the conversation then, but not so glad now.
We walked together so close, and I was walking on air. I felt that I must look the most glamorous guy, a most glamorous guy in the whole wide world.
I asked permission from my host family to move at Barbara’s for the duration of the program and they agreed. I walked to Beverly Hills the next morning to see her in the fashion store she managed. She received me like a VIP and was happy at my surprised visit. I wanted to be with Barbara every second of my trip to California.
I accepted to attend a conference in Los Angeles a couple of years later, hoping to see Barbara again. It was an important political conference but my heart was not in it.
My friends drove me through Beverly Hills where the rich and glamorous live, but I was not impressed. Finally, giving up, they gave me a lift from Anaheim to West Hollywood.
I called up Barbara and I invited myself to stay overnight at her apartment. She had many friends.
She was attached at the moment to a fashionable young man, working in fashion and with fashion, but they had problems. She appeared depressed and disappointed and not in the mood for me. Her TV was on 24 hours. I slept and woke up with the TV on.
I visited her six years later during my second extended trip to the USA: Barbara’s sister had told me that Barbara was married and living in Oklahoma City. She did not look the same Barbara. She was skinnier. Her skin looked darker, her face emaciated, down to earth, resigned and decked in simple blue jeans and an old black sweater.
Barbara was married to a full-blooded American Indian, she a half-blooded.
A soft spoken husband he was, a polite artist who toured the USA exhibiting his paintings. She stayed at home designing jewelry and managing her man’s business.
I had accepted her invitation for a Thanksgiving lunch. I went down to Oklahoma City for an important and specific purpose of mine: I was determined to tell Barbara my secret. I went down with my steady girl friend at the time: I still had no car.
Barbara’s eyes had an ironic shine looking at my oriental short friend. She asked my friend all kinds of questions about our relationship, how we met and what are our plans.
She said to me: “You know, someone needs news about your friend”. She meant that her sister needed to know the whereabouts of her ex-husband. I had lost track of the whereabouts of my friend too and could not be of much help.
Barbara was entitled to know the truth; that the first time she walked with me she made me feel that I was the most glamorous guy in town. But I did not tell Barbara the truth.
I don’t recall that I talked during my two hours stay. Maybe it did not feel right at that moment. But I should have persevered on my initial decision: This truth is hers no matter what.
She could be sixty, but age does not erase the feeling, that to my young eyes, she was the most glamorous woman I set my eyes on. She could live to be a hundred, but age does not change the fact, that Barbara made me once walk on air.
The Sea People (Palestinians) and the 12 tribes
Posted by: adonis49 on: July 12, 2009
The Sea People and the 12 tribes (July 11, 2009)
Around the 13th century BC, “Sea People” of the northern Mediterranean Sea coasts vandalized coastal town and pirated ships in the eastern Mediterranean. Commerce and trade degenerated in that sea, which later on permitted the Phoenician City-States (Tyr, Sidon, Byblos…) commerce and trade to prosper.
Those “sea people”, the ancient precursors of the “Vikings”, spread havoc in Egypt before they were countered and forced to redeploy to Gaza and the southern coast of Palestine (named after the sea people).
It is plausible that the Palestinians returned Not as a block, but in waves to the Palestinian coasts. Many might have shipwrecked and many were lost in deserts (Sinai) before reaching the deserted region in south Palestine (the Negev/ al Nakab).
The fiction stories of Moses and the nomadic “tribes” that he led out of the wilderness might be a symbolic tale, or a mythical tale since there are no archeological facts or records in any civilization of the peregrination of these nomads. Even the stories of the Hebrew tribes raiding urban setting in Canaan (all the region north of current Gaza, all the way to coastal Turkey) are fiction stories: No artifacts or any archeological finding have uncovered anything, and possibly because they were nomads and didn’t leave any long-lasting residue or marks.
As these “Hebrew” tribes got acquainted with Canaan civilization they set aside “Yahweh” (God idol of war) and adopted “El”, the monolithic God of the Land.
Now and then, a few of these nomad tribes generated their own “prophets” to remind them of “Yahweh” in period of dire disaster to strengthen tribal identity and pick up arms, devastation, and desolation.
“Yahweh‘s” anger and thirst for revenge against civilized and settled people had no limits, and the mythical stories in the ancient testament tell how the Canaan settled people had to suffer from the periodic razias of the desert nomads for loots and easy profits, as was the custom for the nomads in the “Arabic Peninsula” who raided Damascus, until the nomads learned to taste the fruits of civilized life. I call these nomads on the borders of the urban agglomerations as the “Tribes of Transmission” of civilized customs and life-style
The process of absorbing nomads into settled life was long.
Frequently, new waves of nomads knocked on the doors of settled people in Canaan and Palestine. The new waves of nomads did not just emerge from the south but they also converged from the north (Turkey), the east (Persia), south-east (Arabic Peninsula), and the west (Greeks and sea people).
The Near East settled civilization, in City-States studded along the Euphrates, Tiger, Orontes Rivers and the coastal region, had to negotiate with warrior nations and infuse in these nations their monotheist religion and philosophy, which spread all around the Middle East.
Like in every religion, every town and city had to adopt a patron saint or demi-god to consecrate and identify its particular characteristics or line of business. Thus, Baal, Astarte, Adonis, Apollo, and all the derivative demi-gods, symbolizing the strength and bounty of nature, were mere representations of particular aspects of the all powerful and omniscient God El.
The Near East has been the melting pot of all kinds of immigrants fleeing from persecution, disasters, wars, harsh life, and soldiers deciding to remain in the land of “honey and milk“.
The trend has reversed: the Near Eastern citizens are immigrating to greener pastures for the same reason they settled down this region thousands of years ago.
The new nomads (apartheid Zionists) are brandishing sophisticated weapons and are abusing the same unyielding barbaric Gods but there are no profitable loots to generate.
The Near East region has been ransacked, impoverished, and depleted of educated and artistic generations.
Now the Near East is succumbing to brutal globalization.
Note: It has been demonstrated that the new human species of Homo Sapiens first settled in the Near-East 100,000 years ago, and from here they migrated to the 5 continents in wave, and the Neolithic Age (10,000 years ago) as mankind started planting and harvesting originated also in the Near-East.
Adonis Diaries 