We simultaneously recorded tracheal sound and air flow from nine normal subjects (seven males and two females). Sound was picked up at the supra sternal notch with an air-coupled sensitive microphone held in a small airtight probe. Flow was measured at the mouth using a pneumotachograph Fleisch n degrees 2. Both sound and flow were directly digitized at a sampling rate of 5120 Hz and then divided in 128-sample blocks. For each sound block the frequency spectrum was computed using the fast Fourier transform. In order to evaluate instantaneous flow-rate from tracheal sounds we investigated eight methods divided in two groups of four. In the first group (i.e., reference curves methods), we assumed that a relationship existed between sound and flow and was thus reflected by the variations of certain parameters. We chose to use simple straightforward relationships, already known and published. We tested four different parameters. During a calibration phase, we built for each parameter P a reference curve representing the variations of P versus flow and being specific to each subject. Then, an unknown flow was evaluated in calculating P on a 128-sample block, and the reference curve gave the corresponding flow. In the second group, we made a hierarchial clustering analysis of sound spectra for revealing the frequency modifications, induced by the flow. We tested two kinds of spectra as well as two ways of associating a flow to a given cluster. This led us to four other methods for calculating the flow. All the eight methods but one gave a mean uncertainty in the measure of flow of about 15%.(ABSTRACT TRUNCATED AT 250 WORDS)
An accurate recording system was set up and used for analyzing normal and asthmatic breath-sound features. Breath sounds are recorded at the trachea simultaneously with the airflow signal at 0.5- and 1-1/s levels. The study was carried out in the frequency domain using a fast-fourier transform (FFT). FFTs are taken on 1,024-sample blocks (one block = 200 ms) over a duration of about 20 s. Different characteristics of the spectra are calculated in the range 60-1,260 Hz for 11 normal and 10 asthmatic subjects. This allows the computation of an index that discriminates (P less than 0.0005) asthma cases from normal cases. Spectral features strongly depend on the flow rate both for normal and asthmatic subjects. Increasing the flow rate raises the high-frequency components of the spectra.
Summary
In the present experiment an attempt was mode to establish the extent to which the conservation responses that are produced by an initially nonconserving child while observing the performance of a conserving model indicate whether the child simply imitates the observed behavior or whether he understands to some extent the principle involved. Five observation situations were designed : in the first four situations observation was interrupted after the experimentees question and the child spoke his or her answer prior to hearing the model's ; in the fifth situation observation was nol interrupted. In the first three situations, the model solved three problems that required an equality judgment and an inequality problem that was given respectively in the second, the third, or the fourth position. In the last two situations, the model solved four equality problems. The data reveal that in the four situations in which observation was interrupted rapid adoption of the modeVs response occurred. In the first three situations, the observers failed the inequality problem : whereas a majority of them only took into account the height of the liquid, those who stated an incorrect equality judgment achieved a higher overall performance during both observation and post-test. In ail five observation situations, acquisition was equivalent but it reached a higher level among the children who gave more conservation responses during observation. Children achieve the comprehension of conservation when they first display frequent imitation of the modeVs response at the time of the observation period.
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