Use of a resonating cavity to measure body volume

Deskins, W.G.; Winter, D. C.; Sheng, Hwai-Ping; Garza, Cutberto

doi:10.1121/1.392346

Cited by 11 publications

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“…[15][16][17][18]) as in the guitar, it has not been previously verified for the violin due to lack of a model for the acoustic conductance of the f-hole. Parameter fit and network analogy approaches to violin modelling [19], rather than fundamental physical formulations that have been developed for the violin and related instruments [5,9,20,21], have led to results inconsistent with classical Helmholtz resonance theory [3][4][5] even for rigid vessels.…”

Section: Introductionmentioning

confidence: 99%

The evolution of air resonance power efficiency in the violin and its ancestors

et al. 2015

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The fact that acoustic radiation from a violin at air-cavity resonance is monopolar and can be determined by pure volume change is used to help explain related aspects of violin design evolution. By determining the acoustic conductance of arbitrarily shaped sound holes, it is found that air flow at the perimeter rather than the broader sound-hole area dominates acoustic conductance, and coupling between compressible air within the violin and its elastic structure lowers the Helmholtz resonance frequency from that found for a corresponding rigid instrument by roughly a semitone. As a result of the former, it is found that as sound-hole geometry of the violin's ancestors slowly evolved over centuries from simple circles to complex f-holes, the ratio of inefficient, acoustically inactive to total sound-hole area was decimated, roughly doubling air-resonance power efficiency. F-hole length then slowly increased by roughly 30% across two centuries in the renowned workshops of Amati, Stradivari and Guarneri, favouring instruments with higher air-resonance power, through a corresponding power increase of roughly 60%. By evolution-rate analysis, these changes are found to be consistent with mutations arising within the range of accidental replication fluctuations from craftsmanship limitations with subsequent selection favouring instruments with higher air-resonance power.

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Section: Introductionmentioning

confidence: 99%

The evolution of air resonance power efficiency in the violin and its ancestors

et al. 2015

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“…Measurements of body volume with the acoustic plethysmograph are based on the principle of the Helmholtz resonator (12,13). The Helmholtz resonator consists of a chamber with a volume of air coupled to a source of sound waves (a speaker).…”

Section: Body Volume Measurement Using Acoustic Plethysmographymentioning

confidence: 99%

“…A detailed discussion of the theory and construction of an early prototype resonating chamber has been published (12,13). Preliminary validation of this method based on measurements of inanimate objects and anesthetized infant miniature pigs demonstrated the potential usefulness of this method for body volume measurements in infants (12,13).…”

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Body Volume and Fat-Free Mass Determinations by Acoustic Plethysmography

et al. 1988

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ABSTRACT. An acoustic plethysmograph designed to measure body volumes of infants is described. This method uses the principle of the Helmholtz resonator in which the resonant frequency of a chamber is inversely proportional to the square root of the volume of air inside the chamber. After an object is placed inside the chamber, the change in resonant frequency is used to measure the volume of the object. The coefficient of variation of repeated measures of body volumes of 13 miniature piglets (5 to 18 days old, body weights 1253 to 2631 g) ranged from 0.3 to 3.2%. Body volumes measured by the acoustic method agree closely with those calculated from carcass analysis in which body volume is the sum of the volumes of total body water, fat, protein, and minerals. Fat-free mass computed from densitometry using a four-compartment model and body volume measurements from the acoustic method agrees with fat-free mass obtained from carcass analysis. The mean difference between methods was not significant: 1 ml for body volume and 3 g for fat-free mass. The limits of agreement between methods was f 75 ml for body volume and f 214 g for fat-free mass. Our results indicate that the acoustic method can measure a change in body volume of 75 ml and a change in fat-free mass of 214 g in a 2000 g infant. (Pediatr Res 24: 85-89, 1988) (7), pressure differential (8, 9), and a combination of water and air displacement (10, 11) have been explored. None of those methods is without technical difficulties: e.g. changes in chamber pressures due to alterations in chamber temperature and respiratory gas exchange and evaporative water losses from the subjects.In collaboration with colleagues from the University of Houston, we developed an acoustic plethysmograph, based on the Helmholtz resonator principle (12, 13). A detailed discussion of the theory and construction of an early prototype resonating chamber has been published (12, 13). Preliminary validation of this method based on measurements of inanimate objects and anesthetized infant miniature pigs demonstrated the potential usefulness of this method for body volume measurements in infants (12, 13).We designed the present experiment to assess the validity of the acoustic plethysmograph to measure body volumes and to estimate the fat-free mass of anesthetized infant miniature pigs. Values of body volume obtained by the acoustic method were compared with estimates of body volume calculated from the chemical analysis of the whole carcass. Values of fat-free mass estimated from body density were compared with those obtained from carcass analysis. METHODSAssessments of energy metabolism and requirements of infants have been impeded by the paucity of acceptable methods to determine body composition. Of the various techniques that have been explored, those based on densitometry (1) have the most appeal because they are noninvasive and can be used repeatedly over short periods.The determination of body density requires the measurement of body mass and volume. Although accurate measures of body...

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“…Although further methods should be developed, we should capitalize on current techniques such as total body electrical conductivity (42), bioelectrical impedance analysis (43), acoustic plethysmography (44), and stable isotope techniques (45) to assess growth and development in infancy more critically. Potential applications of the dual-labeled water method for measuring total energy expenditure (46) are also exciting.…”

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Future Research in Human Milk

Goldman

Garza

1987

Pediatr Res

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ABSTRACT. Because of the importance of breast-feeding to child health, research in the formation, composition, and biological effects of human milk should be strongly encouraged. Future exploration should include the processes that are responsible for the synthesis and secretion of human milk; the nature and function of the physical compartments in human milk; the structure and function of certain proteins and other components in human milk; and the in vivo fate and effect of a host of constituents including nutrients, growth factors, hormones, inducers, immunological factors, and antiinflammatory agents. Because of the potential public health benefits, these studies should be a high priority in pediatric research for the next decade. (Pediatr Res 22: 493-496, 1987)Although the survival of the human species until recently has been dependent on breast-feeding, there has been comparatively little scientific interest in human lactation and the composition and biological effects of human milk. Investigators in this field have usually dealt with questions concerning diseases of specific organs, norms of growth and development in nonbreast-fed populations, or the effects of nutrients other than human milk. Furthermore, most studies dealing with the health of infants o r with the occurrence or treatment of disorders that are prone to develop during infancy have not examined the effect of breastfeeding as an independent variable.

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Use of a resonating cavity to measure body volume

Cited by 11 publications

References 0 publications

The evolution of air resonance power efficiency in the violin and its ancestors

The evolution of air resonance power efficiency in the violin and its ancestors

Body Volume and Fat-Free Mass Determinations by Acoustic Plethysmography

Future Research in Human Milk

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