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Basic and Technical Aspects of Ultrasound
Published in Arianna D'Angelo, Nazar N. Amso, Ultrasound in Assisted Reproduction and Early Pregnancy, 2020
Sound is a pressure wave, that is a mechanical disturbance of a medium, which passes through the medium at a fixed speed. Sound travels through the medium as a series of molecular vibrations, and the speed at which sound travels through the medium depends on the nature of the medium (solid, liquid, or gas). As the position of the molecules can be fixed, particularly in solids, the molecular vibrations travel as a “wave” through the medium, away from the vibrating source. In other words, sound is a variation in pressure, with regions of increased pressure known as the compression part of the wave and regions of decreased pressure known as the rarefaction portion of the wave. In addition, sound is a longitudinal wave, which means that disturbance is in the same direction as that of the propagation of the wave.
Imaging and Principles of Uro-Radiology
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Anuj Goyal, Beth Hickerton, Rebecca Tregunna
Ultrasound can be used as a diagnostic medical imaging technique that utilises the interaction between sound waves and different tissues. Alternative current is applied to crystals of a piezoceramic plate in a transducer. Expansion and contraction of these crystals produce longitudinal waves, typically at a frequency varying between 2 and 18 MHz. In humans, the audible range of sound wave frequency is between 20 and 20,000 Hz. As the sound waves travel through tissues some are reflected back and are converted from their mechanical form to electrical energy by the transducer to produce an image.
Introduction
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The frequency of a sound wave is the number of wave fronts that pass a given point per second and is measured in cycles per second or Hertz (Hz), or in the case of ultrasound, millions of cycles per second or MegaHertz (MHz). In fact, ‘ultrasound’ is defined as that which is beyond the range of human hearing, which is about 18 kHz (a frequency of 18,000 cycles per second). Diagnostic ultrasound frequencies are even higher than this, generally in the range of 2–15 MHz.
Loudness functions for patients with functional hearing loss
Published in International Journal of Audiology, 2022
Saori Shiraki, Takeshi Sato, Ryoukichi Ikeda, Jun Suzuki, Yohei Honkura, Shuichi Sakamoto, Yukio Katori, Tetsuaki Kawase
The loudness function for a 1000 Hz tone was assessed using the one-step subdivision categorical loudness scale shown in Figure 1, since this method is very simple, its resolution is as high as that for the two-step subdivision categorical scaling method (Suzuki et al. 1999). Participants rated the loudness of each tone on a 17-point scale (from 0 to 16) with seven labelled points (cannot hear, very soft, soft, medium, loud, very loud, and too loud). The 1000 Hz tone bursts (duration: 490 ms) were presented once per second using a commercially available audiometer with headphones (audiometer: RION AA-HA; headphones: RION AD-02T, RION Co., Ltd., Tokyo, Japan). The level of the tone was increased from an inaudible level to 90 dB HL or the too-loud level in 5-dB steps (ascending method). The monaural loudness function for each ear was measured twice (alternating between ears), and the average rating for each level was determined. The threshold determined from the loudness function was defined as the minimum sound pressure level at which the average rating of two measurements was 1 or higher.
Hearing health information in Malaysian public schools: a step towards addressing a public health concern
Published in International Journal of Audiology, 2021
Nur Amirah Zakaria, Nashrah Maamor, Nor Haniza Abdul Wahat
Additional sound and hearing-related information was in elective subjects. In Form 4 Biology, students were introduced to the decibel unit and the recommended limit of noise level. There were also activities where students were asked to formulate strategies to reduce excessive noise. In Form 5 Physics and Additional Sciences, more information was given on the characteristics of sound to show the relationship between amplitude and loudness, frequency and pitch, and wavelength and distance. Also covered was how sounds travel differently in different mediums and the movement of molecules that create rarefaction and condensation of sound waves. Noise regulations were taught in Form 4 commerce pertaining to consumer rights to a healthy environment. Basic knowledge of sound as transformable energy was also taught in the Form 4 Basic sustainability subject.
Hearing examinations in Southern Denmark (HESD) database: a valuable tool for hearing-related epidemiological research
Published in International Journal of Audiology, 2021
Manuella Lech Cantuaria, Ellen Raben Pedersen, Frans Boch Waldorff, Mette Sørensen, Jesper Hvass Schmidt
During testing, thresholds could be recorded either normally or with the presence of noise in the opposite ear (i.e. masked thresholds). Final thresholds were replaced by masked thresholds whenever masking was used (TS2). This can be exemplified by audiogram 3 (Figure 2), where the right ear AC thresholds will be equal to the masked thresholds displayed in the figure. Although the corresponding unmasked thresholds are shown in the audiogram, those will no longer be available in the final dataset. When thresholds exceeded the maximum output level measured by the equipment (i.e. no response was given at the maximum sound signal), the maximum available threshold was recorded as the final hearing threshold. For example, the patient with audiogram 4 (Figure 2) would be considered to have a 120 dB loss at 4 kHz.