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PubMed2004

[Fasting and postprandial analysis of bowel sounds and plasma 5-hydroxytryptamine level].

BACKGROUND/AIMS: Auscultation of bowel sounds is a traditional technique for evaluating patients with abdominal symptoms. It is, however, subjective and qualitative method in general. Recently, analysis of bowel sounds becomes possible. We analyzed bowel sounds in healthy volunteers and measured platelet depleted plasma 5-hydroxytryptamine (5-HT) that may be associated with postprandial symptoms in irritable bowel syndrome. METHODS: We recorded both fasting and postprandial bowel sounds for 30 minutes in 16 healthy volunteers with a sensitive electronic stethoscope attached to a digital recorder. The files were saved in computer as wav files and analyzed with a specialized program. Blood samples were also taken before and 1 hour after meal for 5-HT analysis. RESULTS: Meal challenge made no statistically significant changes in the 5-HT concentrations and all the sound parameters including sound to sound interval, sounds/minute, average of sound amplitudes, sound length, percentage of bowel sounds representing sound clustering and dominant frequency of sounds. CONCLUSIONS: Postprandial changes in bowel sounds and plasma 5-HT were insignificant in healthy Korean volunteers.

Adolescent↗
PubMed1998

Validation of a recording protocol for assessing temporomandibular sounds and a method for assessing jaw position.

Sounds are often produced by the temporomandibular joint (TMJ) during movement in both symptomatic and asymptomatic subjects. However, subjective methods of describing these sounds have been shown to have poor inter- and intra-observer reliability. In this study, a low cost system in which TMJ sounds were detected using the loudspeakers of lightweight in-ear headphones as microphones is evaluated. The sounds were recorded on tape and then analysed using a computer. Sounds were elicited by asking subjects to bring their teeth together with sufficient force to produce a tooth contact sound, then open their mouths as far as possible and then close again. Placing the microphones in the ears attenuated ambient sounds by 58%, thus providing a degree of immunity from ambient noise. Sampling was performed on the left microphone only at 3.4 kHz and from the left and right microphones together at 1.7 kHz for 60 TMJ sounds and 60 tooth contact sounds. Spectral analysis of sounds recorded at the two sample rates revealed no significant differences. Therefore, a sample rate of 1.7 kHz is adequate to resolve the frequency components present in the TMJ sounds. Although simply recording TMJ sounds does not give a direct measurement of the position of the mandible, using this protocol allows the length of the open close cycle to be determined. If the envelope of movement is assumed to approximate a sinusoid, then the direction of mandibular movement can be assumed to reverse at the half way point in the cycle. The accuracy of this assumption was calculated by comparing the mid-point of the cycle to the point of maximum gape in 129 cycles from nine subjects. The mean difference expressed as percentage of cycle length was 1.3 +/- 0.9%.

Adolescent↗
PubMed2006

Information extraction from sound for medical telemonitoring.

Today, the growth of the aging population in Europe needs an increasing number of health care professionals and facilities for aged persons. Medical telemonitoring at home (and, more generally, telemedicine) improves the patient's comfort and reduces hospitalization costs. Using sound surveillance as an alternative solution to video telemonitoring, this paper deals with the detection and classification of alarming sounds in a noisy environment. The proposed sound analysis system can detect distress or everyday sounds everywhere in the monitored apartment, and is connected to classical medical telemonitoring sensors through a data fusion process. The sound analysis system is divided in two stages: sound detection and classification. The first analysis stage (sound detection) must extract significant sounds from a continuous signal flow. A new detection algorithm based on discrete wavelet transform is proposed in this paper, which leads to accurate results when applied to nonstationary signals (such as impulsive sounds). The algorithm presented in this paper was evaluated in a noisy environment and is favorably compared to the state of the art algorithms in the field. The second stage of the system is sound classification, which uses a statistical approach to identify unknown sounds. A statistical study was done to find out the most discriminant acoustical parameters in the input of the classification module. New wavelet based parameters, better adapted to noise, are proposed in this paper. The telemonitoring system validation is presented through various real and simulated test sets. The global sound based system leads to a 3% missed alarm rate and could be fused with other medical sensors to improve performance.

Activities of Daily Living↗
PubMedDate not supplied

Frequency spectra of normal expiratory nasal sound.

BACKGROUND: The computerized analysis of the nasal sound reflects the nasal airflow. We have developed a new software program that analyzes the nasal sound to use in the research area and clinical applications. We aimed to analyze automatically the spectral parameters of nasal sound in healthy people by our new versatile PC-based nasal sound analyzer software. METHODS: In this study, we analyzed and recorded the expiratory nasal sound in 30 healthy people. This analysis includes the time-expanded waveform, the spectral analysis with time-averaged fast Fourier transform, the automatic detection, and the waveform analysis of nasal sound. RESULTS: We calculated the mean frequency of low-intensity sound (LIS) and high-intensity sound (HIS). The mean frequency of LIS was found as 1254 +/- 10.23 Hz at the right nose and 1375 +/- 18.45 Hz at the left nose. The mean frequency of HIS was found as 2453 +/- 22.23 Hz at the right nose and as 2234 +/- 21.12 Hz at the left nose. These results showed that the values between LIS and HIS are statistically significant (p < 0.005) and different from each other. We found that the nasal sound of the similar nasal airflow was the same type and amplitude in the analysis of the nasal sound recordings. CONCLUSION: The frequency of the nasal sound is an indicator of the intensity of the nasal airflow. The method that provides the analysis of the nasal sound may lead to a new diagnostic method. The method, which is noninvasive, rapid, of low cost, and even applicable for small children, requires little cooperation of the subjects. In addition, it will be possible to record and save the analysis of the nasal airflow as digital data.

Adolescent↗
PubMed1989

Stimulus duration and repetition rate influence newborns' head orientation toward sound.

Three experiments evaluated the effects of stimulus duration and repetition rate on newborns' head orientation responses. In Experiment 1, 28 infants turned toward a 20-sec continuous rattle sound but not toward 14- and 500-msec rattle sounds. Signal energy as a possible explanation for the infants' difficulty orienting toward brief sounds was explored in Experiment 2. Twenty neonates did not turn toward a single 90 dB, 14-msec rattle sound, although a longer duration (10 sec) sound containing less energy (70 dB) did elicit reliable head orientation. In Experiment 3, 16 neonates heard trains of repeated 14-msec rattle sounds (2/sec, 1.3/sec, and 1/sec) lasting 10 sec as well as a 10-sec continuous rattle sound. They turned toward the most rapidly repeating brief sound and the continuous one, while the slowly repeating sounds elicited little head movement in any direction. These results suggest that newborns' head orientation is selectively deficient for brief sounds, that the difficulty does not result from lessened energy in the brief sounds, and that the efficacy of repeated brief sounds depends upon their repetition rates.

Analysis of Variance↗
PubMed1993

Passive sound localization of prey by the pallid bat (Antrozous p. pallidus).

The pallid bat (Antrozous p. pallidus) uses passive sound localization to capture terrestrial prey. This study of captive pallid bats examined the roles of echolocation and passive sound localization in prey capture, and focused on their spectral requirements for accurate passive sound localization. Crickets were used as prey throughout these studies. All tests were conducted in dim, red light in an effort to preclude the use of vision. Hunting performance did not differ significantly in red light and total darkness, nor did it differ when visual contrast between the terrestrial prey and the substrate was varied, demonstrating that the bats did not use vision to locate prey. Our bats apparently used echolocation for general orientation, but not to locate prey. They did not increase their pulse emission rate prior to prey capture, suggesting that they were not actively scanning prey. Instead, they required prey-generated sounds for localization. The bats attended to the sound of walking crickets for localization, and also attacked small, inanimate objects dragged across the floor. Stationary and/or anesthetized crickets were ignored, as were crickets walking on substrates that greatly attenuated walking sounds. Cricket communication sounds were not used in prey localization; the bats never captured stationary, calling crickets. The accuracy of their passive sound localization was tested with an open-loop passive sound localization task that required them to land upon an anesthetized cricket tossed on the floor. The impact of a cricket produced a single 10-20 ms duration sound, yet with this information, the bats were able to land within 7.6 cm of the cricket from a maximum distance of 4.9 m. This performance suggests a sound localization accuracy of approximately +/- 1 degree in the horizontal and vertical dimensions of auditory space. The lower frequency limit for accurate sound localization was between 3-8 kHz. A physiological survey of frequency representation in the pallid bat inferior colliculus suggests that this lower frequency limit is around 5 kHz.

Animals↗
PubMed2006

Sound-symbolism: a piece in the puzzle of word learning.

Sound-symbolism is the idea that the relationship between word sounds and word meaning is not arbitrary for all words, but rather that there are subsets of words in the world's languages for which sounds and their symbols have some degree of correspondence. The present research investigates sound-symbolism as a possible route to the learning of an unknown word's meaning. Three studies compared the guesses that adult participants made regarding the potential meanings of sound-symbolic and non-sound symbolic obsolete words. In each study, participants were able to generate better definitions for sound-symbolic words when compared to non-sound symbolic words. Participants were also more likely to recognize the meanings of sound symbolic words. The superior performance on sound-symbolic words held even when definitions generated on the basis of sound association were eliminated. It is concluded that sound symbolism is a word property that influences word learning.

Humans↗
PubMed2001

Relating cluster and population responses to natural sounds and tonal stimuli in cat primary auditory cortex.

Most information about neuronal properties in primary auditory cortex (AI) has been gathered using simple artificial sounds such as pure tones and broad-band noise. These sounds are very different from the natural sounds that are processed by the auditory system in real world situations. In an attempt to bridge this gap, simple tonal stimuli and a standard set of six natural sounds were used to create models relating the responses of neuronal clusters in AI of barbiturate-anesthetized cats to the two classes of stimuli. A significant correlation was often found between the response to the separate frequency components of the natural sounds and the response to the natural sound itself. At the population level, this correlation resulted in a rate profile that represented robustly the spectral profiles of the natural sounds. There was however a significant scatter in the responses to the natural sound around the predictions based on the responses to tonal stimuli. Going the other way, in order to understand better the non-linearities in the responses to natural sounds, responses of neuronal clusters were characterized using second order Volterra kernel analysis of their responses to natural sounds. This characterization predicted reasonably well the amplitude of the response to other natural sounds, but could not reproduce the responses to tonal stimuli. Thus, second order non-linear characterizations, at least those using the Volterra kernel model, do not interpolate well between responses to tones and to natural sounds in auditory cortex.

Acoustic Stimulation↗
PubMed1969

Classification of inferior collicular neurones of bats in terms of responses to pure tones, FM sounds and noise bursts.

1. Single unit activity in the inferior colliculus of bats was studied with pure tones, FM (frequency-modulated) sounds and noise bursts which are the most basic three components of the complex sounds produced by many different animals including man. Neurones were divided into three groups, (i) ;generalized' units responding to all three elements, (ii) ;deaf' units responding to two out of the three and (iii) ;specialized' units responding to only one of the three. Each of these was divided into three subgroups.2. Three subgroups of generalized units were called ;symmetrical', ;asymmetrical' and ;upper-threshold' units. The symmetrical unit had a wide excitatory area and responded to any sounds which had components falling in this area. The asymmetrical unit had a narrow excitatory area abutting on a large inhibitory one and showed different responses to FM sounds depending on the directions of frequency sweep. The upper-threshold unit had not only an excitatory area, but also an inhibitory one. The neurone failed to respond to strong sounds, i.e. these showed upper thresholds.3. Three subgroups of deaf units were called ;pure tone-deaf', ;FM-deaf' and ;noise-deaf' units. The pure tone-deaf unit did not respond to any pure tones but did respond to FM sounds and noise bursts. The noise-deaf unit did not respond to noise bursts but did respond to pure and FM tone pulses. An FM-deaf unit has not yet been confirmed.4. Three subgroups of specialized units were called ;pure tone-specialized', ;FM-specialized' and ;noise-specialized' units which responded exclusively to either pure tones, FM sounds or noise bursts, respectively. In the FM- and noise-specialized units, pure tone pulses caused only inhibitory processes.5. About 95% of neurones studied showed phasic on-responses to sound stimuli and almost no spontaneous discharges. Only a small percent of neurones showed spontaneous discharges higher than a few impulses per second. Response patterns of some of these neurones changed with frequency, intensity, duration and repetition rate of sound stimuli. These neurones responded to any of pure tones, FM sounds and noise bursts.6. All neurones except the symmetrical ones had inhibitory areas, in which sounds inhibited responses to excitatory ones when these are delivered simultaneously. Therefore the structure in complex sounds is very important in the excitation of these neurones.

Animals↗
PubMed2003

Modulation spectra of natural sounds and ethological theories of auditory processing.

The modulation statistics of natural sound ensembles were analyzed by calculating the probability distributions of the amplitude envelope of the sounds and their time-frequency correlations given by the modulation spectra. These modulation spectra were obtained by calculating the two-dimensional Fourier transform of the autocorrelation matrix of the sound stimulus in its spectrographic representation. Since temporal bandwidth and spectral bandwidth are conjugate variables, it is shown that the joint modulation spectrum of sound occupies a restricted space: sounds cannot have rapid temporal and spectral modulations simultaneously. Within this restricted space, it is shown that natural sounds have a characteristic signature. Natural sounds, in general, are low-passed, showing most of their modulation energy for low temporal and spectral modulations. Animal vocalizations and human speech are further characterized by the fact that most of the spectral modulation power is found only for low temporal modulation. Similarly, the distribution of the amplitude envelopes also exhibits characteristic shapes for natural sounds, reflecting the high probability of epochs with no sound, systematic differences across frequencies, and a relatively uniform distribution for the log of the amplitudes for vocalizations. It is postulated that the auditory system as well as engineering applications may exploit these statistical properties to obtain an efficient representation of behaviorally relevant sounds. To test such a hypothesis we show how to create synthetic sounds with first and second order envelope statistics identical to those found in natural sounds.

Animals↗
PubMed1975

Transmission of audible praecordial gallop sounds to right supraclavicular fossa.

To evaluate the significance of audible gallop sounds in the right supraclavicular fossa we performed simultaneous external heart sound recordings at 50 and 100 Hz at the left ventricular apex, left sternal border, and right supraclavicular fossa in 50 patients with audible gallop sounds at the left ventricular apex. In each patient heart sounds were recorded with a simultaneous jugular phlebogram, apex cardiogram, and carotid pulse tracing. In 44 patients an apical fourth heart sound coincident with the 'a' wave of the apex cardiogram was recorded, and in 32 (73%) the fourth heart sound was audible and recordable in the right supraclavicular fossa. A left ventricular third heart sound, coincident with the rapid filling wave of the apex tracing, was present in 25 patients but was recorded in the right supraclavicular fossa in only 7 (28%). Intracardiac phonocardiography (high-fidelity catheter) was performed in six patients with left ventricular gallop sounds and in each instance arterial transmission of the third or fourth heart sound, or both, was present. Five additional patients had a prominent jugular venous 'a' wave, but only two had a soft parasternal fourth heart sound. Intracardiac phonocardiography in these five patients failed to reveal transmission of right ventricular gallop sounds to the superior vena cava. We conclude that since left ventricular gallop sounds commonly are transmitted to the right supraclavicular fossa auscultation in this area is often helphful in their detection. In addition, a prominent jugular venous 'a' wave sometimes produces recordable presystolic vibrations that are occasionally audible as well.

Clavicle↗
PubMed1976

Investigation of the theory and mechanism of the origin of the second heart sound.

To investigate further the origin of the second heart sound we studied human subjects, dogs, and a model in vitro of the cardiovascular system. Intra-arterial sound, pressure, and, where possible, flow and high speed cine (2,000 frames/sec) were utilized. The closure sound of the semilunar valves was of higher amplitude in be ventricles than in their respective arterial cavities. The direction of inscription of the main components of intra-arterial sound were opposite in direction to the components of intraventricular sound. Notches, representative of pressure increments, were noted on the ventricular pressure tracings and were coincident with the components of sound. The amplitude of the closure sound varied with diastolic pressure, but remained unchanged with augmentation of forward and retrograde aortic flow. Cines showed second sound to begin after complete valvular closure, and average leaflet closure rate was constant regardless of pressure. Hence, the semilunar valves, when closed, act as an elastic membrane and, when set into motion, generate compression and expansion of the blood, producing transient pressure changes indicative of sound. The magnitude of the initial stretch is related to the differential pressure between the arterial and ventricular chambers. Sound transients which follow the major components of the second sound appear to be caused by the continuing stretch and recoil of the leaflets. Clinically unexplained findings such as the reduced or absent second sound in calcific aortic stenosis and its paradoxical presence in congenital aortic stenosis may be explained by those observations.

Animals↗
PubMed2005

The selection of introduced sounds to improve the soundscape in the public spaces.

The purpose of introducing sounds is to afford a comfortable acoustic environment and to design good soundscapes. This study aims at rating the preference of subjects for the introduced sounds suitable to the public spaces and also investigates the methodology to select the sounds by subjective and objective procedures. Seventeen kinds of the introduced sounds were evaluated with nine adjectives in the presence of visual location information. Also, adequate sound levels were calculated by adjusting the volume of introduced sounds in the presence of the actual background sounds of locations and visual information. The concept of harmony with the surroundings was reviewed by analyzing the correlation among 9 adjectives which express introduced sounds. And the effectiveness of existed sound quality index was analyzed so as to select the introduced sounds quantitatively. By the evaluation of the adequate level of the introduced sounds, it is proposed that the lower introduced sound level would be better for the noisy circumstances.

Adult↗
PubMed2006

New non-invasive automatic cough counting program based on 6 types of classified cough sounds.

UNLABELLED: Cough consisting of an initial deep inspiration, glottal closure, and an explosive expiration accompanied by a sound is one of the most common symptoms of respiratory disease. Despite its clinical importance, standard methods for objective cough analysis have yet to be established. OBJECT: We investigated the characteristics of cough sounds acoustically, designed a program to discriminate cough sounds from other sounds, and finally developed a new objective method of non-invasive cough counting. In addition, we evaluated the clinical efficacy of that program. SUBJECTS AND METHODS: We recorded cough sounds using a memory stick IC recorder in free-field from 2 patients and analyzed the intensity of 534 recorded coughs acoustically according to time domain. First we squared the sound waveform of recorded cough sounds, which was then smoothed out over a 20 ms window. The 5 parameters and some definitions to discriminate the cough sounds from other noise were identified and the cough sounds were classified into 6 groups. Next, we applied this method to develop a new automatic cough count program. Finally, to evaluate the accuracy and clinical usefulness of this program, we counted cough sounds collected from another 10 patients using our program and conventional manual counting. And the sensitivity, specificity and discriminative rate of the program were analyzed. RESULTS: This program successfully discriminated recorded cough sounds out of 1902 sound events collected from 10 patients at a rate of 93.1%. The sensitivity was 90.2% and the specificity was 96.5%. CONCLUSION: Our new cough counting program can be sufficiently useful for clinical studies.

Cough↗
PubMed2002

Sound signature for identification and quantification of upper airway disease in horses.

OBJECTIVE: To investigate whether upper airway sounds of horses exercising with laryngeal hemiplegia and alar fold paralysis have distinct sound characteristics, compared with unaffected horses. ANIMALS: 6 mature horses. PROCEDURE: Upper airway sounds were recorded in horses exercising on a high-speed treadmill at maximum heart rate (HR(MAX)) under 3 treatment conditions (ie, normal upper airway function [control condition], and after induction of left laryngeal hemiplegia or bilateral alar fold paralysis) in a randomized crossover design. Fundamental frequency, spectrograms using Gabor transform, and intensity characteristics of acquired sounds (peak sound level [sound(peak] and highest frequency of at least -25 dB sound intensity [F(25max)]) were evaluated. RESULTS: Evaluation of the fundamental frequency of the time domain signal was not useful. Sensitivity and specificity (83 and 75%, respectively) of spectrograms were greatest at maximal exercise, but the exact abnormal condition was identified in evaluation of only 12 of 18 spectrograms. Increased accuracy was obtained using sound(peak) and F(25max) as discriminating variables. The use of sound(peak) discriminated between control and laryngeal hemiplegia conditions and F(25max) between laryngeal hemiplegia and alar fold paralysis conditions. This increased the specificity of sound analysis to 92% (sensitivity 83%) and accurately classified the abnormal state in 92% of affected horses. CONCLUSIONS AND CLINICAL RELEVANCE: Sound analysis might be a useful adjunct to the diagnosis and evaluation of treatment of horses with upper airway obstruction, but would appear to require close attention to exercise intensity. Multiple measurements of recorded sounds might be needed to obtain sufficient accuracy for clinical use.

Airway Obstruction↗
PubMed2005

Attentional modulation of electrophysiological activity in auditory cortex for unattended sounds within multistream auditory environments.

In three experiments, we addressed the issue of attention effects on unattended sound processing when one auditory stream is selected from three potential streams, creating a simple model of the cocktail party situation. We recorded event-related brain potentials (ERPs) to determine the way in which unattended, task-irrelevant sounds were stored in auditory memory (i.e., as one integrated stream or as two distinct streams). Subjects were instructed to ignore all the sounds and attend to a visual task or to selectively attend to a subset of the sounds and perform a task with the sounds (Experiments 1 and 2). A third (behavioral) experiment was conducted to test whether global pattern violations (used in Experiments 1 and 2) were perceptible when the sounds were segregated. We found that the mismatch negativity ERP component, an index of auditory change detection, was evoked by infrequent pattern violations occurring in the unattended sounds when all the sounds were ignored, but not when attention was focused on a subset of the sounds. The results demonstrate that multiple unattended sound streams can segregate by frequency range but that selectively attending to a subset of the sounds can modify the extent to which the unattended sounds are processed. These results are consistent with models in animal and human studies showing that attentional control can limit the processing of unattended input in favor of attended sensory inputs, thereby facilitating the ability to achieve behavioral goals.

Acoustic Stimulation↗
PubMed1999

Assessment of perceived mechanical heart valve sound level in patients.

BACKGROUND AND AIM OF THE STUDY: When mechanical heart valves close, they generate an impulse that is transmitted to the patient's inner ear by two routes: (i) As acoustically transmitted sound waves; and (ii) as vibrations transmitted through bones and vessels. The aim of this study was to quantitate what patients perceive as sound from their mechanical heart valve prostheses - including both air-transmitted sound waves and bone-transmitted vibrations. METHODS: Thirty-four patients with implanted mechanical bileaflet aortic and mitral valves (St. Jude Medical and On-X) were included in the study. Measurements were performed in a specially designed sound-insulated chamber equipped with microphones, accelerometers, preamplifiers and a loud-speaker. The closing sounds measured by an accelerometer on the patient's chest were delayed 400 ms, amplified and played back to the patient through the loudspeaker. The patient adjusted the feedback sound to the same level as the 'real-time' clicks they perceived directly from their valve. In this way the feedback sound energy includes both the air- and bone-transmitted energies. Sound pressure levels (SPL) were quantitated in both dB(A) and in loudness units (sones) according to ISO 532B (Zwicker method). RESULTS: The mean air-transmitted SPL measured close to the patient's ear was 23 +/- 4 dB(A). The total air-and bone-transmitted sounds and vibrations were perceived by the patients as a SPL of 34 +/- 5 dB(A). There was no statistically significant difference in perceived sound from the two bileaflet valves investigated, and no difference between aortic and mitral valves. CONCLUSIONS: The study showed that the presented feedback method is capable of quantitating the perceived sounds and vibrations from mechanical heart valves, if the patient's hearing is not too impaired. Patients with implanted mechanical heart valve prostheses seem to perceive the sound from their valve two to four times higher than nearby persons, because of the additional bone-transmitted vibrations.

Adaptation, Psychological↗
PubMed1996

Application of multivariate linear discriminant analysis to lung sounds in some pulmonary diseases.

In the past 15 yrs, a number of investigators have applied spectral analysis to respiratory sounds recorded from the chest wall or the trachea in order to objectively characterize them and to relate them with different pulmonary diseases. In the present study, we have applied multivariate linear discriminant analysis to the spectral features of respiratory sounds. Lung sounds and the airflow velocity were recorded from 15 normal adults and 37 patients falling into three different disease categories: chronic obstructive lung disease, bronchial asthma and bronchiectasis. All patients had prominent adventitious lung sounds (i.e. either wheezes or crackles). Amplitude spectra of five selected inspiratory and expiratory sound segments of each subject were calculated using the Fast Fourier Transform algorithm. Multi-variate linear discriminant analysis was then applied to the normalized and averaged spectral area values calculated for 10 unequal and arbitrarily selected frequency bands for each patient in the frequency range between 80 Hz and 1 kHz. Inspiratory and expiratory sounds were treated separately. Discriminant functions were computed from the spectral area values and plotted on graphs to classify the subjects into one of the disease categories or as normal (training set). While some separation was achieved among the different disease groups, a clearer separation was evident between normals and patients as a whole on the basis both of inspiratory and expiratory sounds. Inspiratory and expiratory sound frequency bands having the largest weights in classification were determined. Admittedly, the specific results of this study are preliminary or even tentative in view of the inadequacies of sound recording and signal conditioning techniques that were available to us at the time of recording. However, we believe that the investigation serves to illustrate the potential of multivariate discriminant analysis in the diagnostic classification of patients on the basis of their lung sound patterns. We suggest that this technique be considered by investigators involved in lung sound research, because it also allows other patient variables to be combined with the selected parameters of lung sounds.

Adult↗