Physicians have traditionally relied in succession the use of trained vigilances and ears for accurate medical diagnosis.

Physicians have traditionally relied in succession the use of trained vigilances and ears for accurate medical diagnosis, skills that are no les important since the advent of technologic aids in evaluating make and function. Yet, seeing and hearing are not enough. A visual or auditory image must be processed; compared to remembered images, searching for recognizable patterns; and, not finding them, interpreted in light of a base of knowledge of edifice and function. When Holmes says, "My dear Watson, you descry but you do not observe:" it is surpassingly likely the echo of Sir Joseph Bell chiding the young Conan Doyle, a medical scholar at the University of Edinburgh, for missing another diagnosis. Observing is processing. It is the processing of visual and auditory images that is crucial, not simply seeing and hearing.

For through the whole extent of 185 years, physicians have been struggling to proces the goods emanating from the chest in order to better assess the alterations in make and function of the patient. They have struggl on the same level more to transmit their understanding of these unmutilateds to naive, willing, but disbelieving pupils Anyone who has tried to instruct close examiners in the interpretation of lung unhurts heard through the stethoscope remembers the frustration and hand waving. A picture is worth a thousand words, on the other hand the abstract nature of entire and smell compared to vision afflictively limits the transmission of appreciation of these sensations to another in any moreover the crudest form. Having struggl first with the unaided ear, then with a woody cylinder, and more recently with a plastic diaphragm, smooth in a stereo configuration, physicians have either abandoned the stethoscope in favor of expensive technology or have sought better ways of listening. one investigators have resorted to application of digital electronics to perform the processing, with equal reason that objective images can be shared.

The time has arise to place lung sounds analysis forward an objective scientific basis. To do in such a manner requires (1) standardization of deeds and processing, (2) development of testable theoretical prototypes that account for acoustic behavior and interactions of relevant manner of makings and (3) experimental validation of theoretical types in physiologically and structurally quantifiable patterns of disease. Only then will the acoustic images that are generated accurately cogitate structure and function so that they can be shared as objective evidence with colleagues and learners for the welfare of patients. Pasterkamp et al, writing in this issue of Chest (see page 1518) are to be congratulated for leading the way in achieving the first goal, the standardization of acoustical measurements.

They have demonstrated, using sophisticated signal-processing techniques, that level after standardizing measurements for airflow rates and normalizing to background noise, there are important differences in whole spectra that depend on the choice of sensor, the subdue and the type of "window" used to even the data. There was smooth a substantial difference between sum of two units sensors of the same manufacturer.

Air-coupled sensors (microphones) and contact sensors had similar signal-to-noise ratios, if it be not that the former severely attenuated entires about 600 Hz and would be inappropriate for analysis of undecayeds above this level, such as those from the trachea and possibly from peripheral airways. This riddle is inherent in the design of an air-coupled sensor, probably resulting from damping of the higher frequencies in the air chamber. As the same might have guessed, the sensor that performed the best at all frequencies up to 2000 Hz was the chiefly expensive and most fragile. Nevertheless, these be deriveds identify the need for minimum standards in sensors used for respiratory unimpaireds analysis, standards that should include not solely an optimal signal-to-noise ratio at all relevant frequencies moreover also robust design and affordable price. It should also be observ that free-field standardization, which is generally reported through the manufacturer, is insufficient characterization of a sensor that will be used directly or indirectly coupl to the chest wall.

undivided of their subjects exhibited a signal-to-noise ratio more than 50 percent better than those of the other couple a difference that reportedly could be readily appreciated as increased intensity heard with a stethoscope This finding prompts that standardization of the intensity and frequent occurrence of sound input are important, in like manner that such observed differences can be better related to arrangement of parts rather than differences in good generation. Further studies will be wanted to determine whether sensor position should also be uniform.

The investigators sampled respiratory hardys when airflow rates were 15 to 25 L/ of the like kind flow rates will generally be achieved during tidal breathing in healthy men still are unlikely to be achieved in smaller individuals, as it is as young women and children, or in those with airway pathology that introduces grow limitation. Pasterkamp et al allude to as one method of standardizing this parameter, that spring rates be normalized to dead body weight. Since tidal volume scales with dead body weight from infancy through adulthood and inspiratory time is approximately constant through the whole extent of the age span, flow rate will be constant when normalized to dead body weight. On the other hand, origins of hales are sufficiently uncertain and the buildings through which those sounds travel are sufficiently different between adults and infants that standardization of the input undecayed seems to be a better alternative than using naturally generated breath sounds

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