Smells sensing

Sensory is the science of measurement with the human senses. Panelists measure subjective and individually to produce an only one objective final result. Mention of the human senses normally brings to mind the usual 5 senses, smell, taste, vision, hearing and touch. In both the sensory and the physiological sense we better speak of the modalities sense of smell, sense of taste, sense of seeing, sense of hearing and sense of touch (tactile or haptic sense). 

Focus on producing pressure sensors with an operating temperature of up to 225°C Semiconductor gas sensors aiming to realize a gas detection system, which is equivalent to or superior to a human sense of smell Sensing elements, devices, instruments, and systems that enable our customers to monitor, protect, control, and validate their critical processes and apphcations Hazard detection and life protection... 

It quickly deadens the sense of smell. Sulfur dioxide is a dangerous component in atmospheric air pollution. 

Human perception creates difficulty ia the characterization of flavor people often, if not always, perceive flavors differently due to both psychological and physiological factors. For example, certain aryl thiocarbamates, eg, phenylthiocarbamide, taste exceedingly bitter to some people and are almost tasteless to others (5). This difference is genetically determined, and the frequency of its occurrence differs from one population to another 40% of U.S. Caucasians are nontasters, whereas only 3% of the Korean population caimot perceive the strong bitter taste of the aryl thiocarbamates (6). Similar differences were found ia the sense of smell for compounds such as menthol, carvone, and ethyl butyrate (7). 

Flavor has been defined as a memory and an experience (1). These definitions have always included as part of the explanation at least two phenomena, ie, taste and smell (2). It is suggested that in defining flavor too much emphasis is put on the olfactory (smell) and gustatory (taste) aspects (3), and that vision, hearing, and tactile senses also contribute to the total flavor impression. Flavor is viewed as a division between physical sense, eg, appearance, texture, and consistency, and chemical sense, ie, smell, taste, and feeling (4). The Society of Flavor Chemists, Inc, defines flavor as "the sum total of those characteristics of any material taken in the mouth, perceived principally by the senses of taste and smell and also the general senses of pain and tactile receptors in the mouth, as perceived by the brain" (5). 

Whatever the physiology of odor perception may be, the sense of smell is keener than that of taste (22). If flavors are classed into odors and tastes as is common practice in science, it can be calculated that there are probably more than 10 possible sensations of odor and only a few, perhaps five, sensations of taste (13,21,35—37). Just as a hereditary or genetic factor may cause taste variations between individuals toward phenylthiourea, a similar factor may be in operation with odor. The odor of the steroid androsterone, found in many foods and human sweat, may eflcit different responses from different individuals. Some are very sensitive to it and find it unpleasant. To others, who are less sensitive to it, it has a musk or sandalwood-like smell. Approximately 50% of the adults tested cannot detect any odor even at extremely high concentrations. It is befleved that this abiUty is genetically determined (38). 

Jiutosmia. Disorder of the sense of smell in which odors are perceived when none are present. 

Flavor. The sensation produced by a material taken into the mouth, perceived principally by the senses of taste and smell, but also by the common chemical sense produced by pain, tactile, and temperature receptors in the mouth. 

Microsmatic. Having a poorly developed sense of smell. 

Parosmia. A disturbance to the sense of smell resulting ia smelling the wrong odors, usually perceived as repulsive. 

The vomeronasal organ (VNO), located in the nose, is a small chemical sensing stmcture associated with odors and behavioral effects. The vomeronasal system, which is made up of the VNO and a portion of the brain s limbic system, is stmcturaHy independent of the olfactory and nervous terminalis systems in the nose. It may, however, interact with these systems in a manner dependent on prior experience or learning, and therefore be direcdy related to the association of smells and experiences. This independent chemosensory system in the nose may prove to open doors to new learning associated with the sense of smell and human behavior. 

In 1986, the National Geographic Society, in cooperation with the MoneU Center, conducted a worldwide survey of the sense of smell. Over 10 million survey forms were sent to readers of the Society s journal, of which close to 1.5 million forms were completed and returned. With responses to 40 demographic and 42 odor-related questions, the results constitute the largest set of data on human olfaction (4). 

There are certain weU-estabUshed facts about olfaction (6). AU normal people can smell. People suffering from brain lesions, injured olfactory nerve, or obstmcted nasal passages may be anosmic. Cases of preferential anosmia, ie, abUity to sense certain smells and not others, are not weU estabUshed. Such cases occur, but Utde is known of them. 

The sense of smell is rapidly fatigued. Fatigue for one odor does not affect the perception of other dissimUar odors, but wUl interfere with the perception of similar odors. Two or more odorous substances may cancel each other out this compensation means that two odorous substances smelled together may be inodorous. 

Odor travels downwind. Many animals have a keener sense of olfaction than humans. Insects have such extraordinary keenness of smell that it may be a different modaUty of the chemical sense from that known to humans. 

Odors play a much greater role in human behavior than previously thought. The sense of smell provides a direct link with the function of the brain therefore, the further study of olfaction can only advance the learning of causes and effects of stimuli to the brain. 

Cross-country gas pipelines generally must odorize the normally odorless, colorless, and tasteless gas ia urban and suburban areas, as is required of gas distribution companies. Organosulfur compounds, such as mercaptans, are usually used for this purpose, and code requires that the odor must be strong enough for someone with a normal sense of smell to detect a gas leak iato air at one-fifth the lower explosive limit of gas—air mixtures. The latter is about 5%, so the odorant concentration should be about 1%, but most companies odorize more heavily than this as a safety precaution. 

The odor threshold of carbon disulfide is about 1 ppm in air but varies widely depending on individual sensitivity and purity of the carbon disulfide. However, using the sense of smell to detect excessive concentrations of carbon disulfide is unreHable because of the frequent co-presence of hydrogen sulfide that dulls the olfactory sense. 

Some materials with low odour duesholds may paralyse die olfactory nerves and cause the sense of smell to be lost within minutes (e.g. hydrogen sulphide). 

Workers may become acclimatized to a commonly-occuiTing odour, or be suffering temporarily from an impaired sense of smell, e.g. due to a cold. 

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