- 1. Sympathetic or forced vibration of air in the cavities above, below, in front of, or behind a source of sound; in speech, modification of the quality ( e.g., harmonics) of a tone by the passage of air through the chambers of the nose, pharynx, and head, without increasing the intensity of the sound. 2. The sound obtained on percussing a part that can vibrate freely. 3. The intensification and hollow character of the voice sound obtained on auscultating over a cavity. 4. In chemistry, the manner in which electrons or electric charges are distributed among the atoms in compounds that are planar and symmetric, particularly those with conjugated (alternating) double bonds; the existence of r. in the latter case lowers the energy content and increases the stability of a compound. 5. The natural or inherent frequency of any oscillating system. 6. SYN: resonant frequency. [L. resonantia, echo, fr. re-sono, to resound, to echo]- amphoric r. a percussion sound, like that produced by striking a large empty bottle, obtained by percussing over a pulmonary cavity. SYN: cavernous r..- bandbox r. SYN: vesiculotympanitic r..- bellmetal r. in cases of a large pulmonary cavity or of pneumothorax, a clear metallic sound obtained by striking a coin, held against the chest, by another coin, or by flicking the chest wall with one's fingernail; the sound is heard on auscultating the chest wall on the same side anteroposteriorly. SYN: anvil sound, bell sound, coin test.- cracked-pot r. a peculiar sound, resembling that heard on striking a cracked pot, elicited on percussing over a pulmonary cavity that communicates with a bronchial tube, when the patient's mouth is open. SYN: cracked-pot sound.- electron spin r. (ESR) a spectrometric method, based on measurement of electron spins and magnetic moments, for detecting and estimating free radicals in reactions and in biologic systems. SYN: electron paramagnetic r..- nuclear magnetic r. (NMR) the phenomenon in which certain atomic nuclei possessing a magnetic moment will precess around the axis of a strong external magnetic field, the frequency of precession (Larmor frequency) being specific for each nucleus and the strength of the magnetic field; spinning nuclei induce their own oscillating magnetic fields and therefore emit electromagnetic radiation that can produce a detectable signal at the Larmor frequency. NMR is used as a method of identifying covalent bonds and is applied clinically in magnetic r. imaging.- skodaic r. a peculiar, high-pitched sound, less musical than that obtained over a cavity, elicited by percussion just above the level of a pleuritic effusion. SYN: Skoda sign, Skoda tympany.- vesiculotympanitic r. a peculiar, partly tympanitic, partly vesicular sound, obtained on percussion in cases of pulmonary emphysema. SYN: bandbox r., wooden r..- wooden r. SYN: vesiculotympanitic r..
* * *1) a quality imparted to voiced sounds by vibration in anatomical resonating chambers or cavities (as the mouth or the nasal cavity)2) the sound elicited on percussion of the chest3) the conceptual alternation of a chemical species (as a molecule or ion) between two or more equivalent allowed structural representations differing only in the placement of electrons that aids in understanding the actual state of the species as an amalgamation of its possible structures and the usu. higher-than-expected stability of the species4 a) the enhancement of an atomic, nuclear, or particle reaction or a scattering event by excitation of internal motion in the system
* * *res·o·nance (rezґo-nəns) [L. resonare to echo] 1. the prolongation and intensification of sound produced by transmission of its vibrations to a cavity, especially a sound elicited by percussion. See also dullness and flatness. 2. a vocal sound as heard in auscultation. mesomerism.
Medical dictionary. 2011.