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Dolder, C. N., Fletcher, M. D., Jones, S. L., Lineton, B., Dennison, S., & Symmonds, M., et al. (2018). Measurements of ultrasonic deterrents and an acoustically branded hairdryer: Ambiguities in guideline compliance. The Journal of the Acoustical Society of America, 144(2564), 2565–2574.
Added by: Mark Grimshaw-Aagaard 08/12/2022, 06:01
Dolder, C. N., Fletcher, M. D., Jones, S. L., Lineton, B., & Leighton, T. G. 2019, September 9–13. Exposure levels for parametric arrays in light of guideline ambiguities. Paper presented at 23rd International Congress on Acoustics.
Added by: Mark Grimshaw-Aagaard 08/12/2022, 05:43
Duck, F., & Leighton, T. G. (2018). Frequency bands for ultrasound, suitable for the consideration of its health effects. Journal of the Acoustical Society of America, 144(4), 2490–2500.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 07/11/2023, 11:33
Fletcher, M. D., Jones, S. L., White, P. R., Dolder, C. N., Lineton, B., & Leighton, T. G. (2018). Public exposure to ultrasound and very high-frequency sound in air. The Journal of the Acoustical Society of America, 144(4), 2554–2564.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 28/11/2022, 08:00
Leighton, T. G. (2007). What is ultrasound? Progress in Biophysics and Molecular Biology, 93(1–3), 3–83.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 06/04/2022, 12:16
"Foetal ultrasonic scanning is now so established in industrialised nations that it would now be difficult to find a control group for epidemiological studies."
"The limiting feature for the use of ultrasound in air is the severe absorption which rapidly reduces the amplitude of the field, as it propagates away from the source, to levels which are too low for most processing activities, or even to provide sufficient signal-to-noise ratios (SNRs) for many diagnostic applications. There is however one exception, the manifestation of which illustrates a key point which must be appreciated in the assessment of the safety of ultrasound in air. "The human ear is an extremely sensitive sensor for acoustic waves. Intensities which are low by the standards used for ultrasonic diagnostic technology, and certainly for ultrasonic processing, are generally very much higher than the maximum intensities which the human ear can sustain at audio frequencies without damage. Therefore when ultrasound is used to generate signals to which the ear can responds [sic] (which may not necessarily be restricted to audio frequencies—see Section 6), whilst the resulting intensities may be thought of as ‘low’ from the perspective of many ultrasonic technologies, they may be ‘high’ from the perspective of the ear. This point is discussed further in Section 7."
"Given the paucity of information on the safe levels for human exposure to ultrasound in air (Section 6), and the lack of traceability for the measurement of such fields (see Section 2.3), this could be a safety issue."
Leighton suggests three categories of exposure to ultrasound production, the first of which he classifies as ultrasonic noise exposure: ultrasound generated by some device as a byproduct of its operation (unintended exposure) ultrasound generated explicitly by some device and fundamental to its operation (unintended exposure e.g., ultrasonic rangefinder, automatic door openers) ultrasound generated in order to have an effect on humans and/or to change their behaviour (intended exposure).
Leighton, T. G. (2016). Are some people suffering as a result of increasing mass exposure of the public to ultrasound in air? Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 472(2185).
Added by: Mark Grimshaw-Aagaard 07/11/2023, 11:31
"recent data suggest 1 in 20 people aged 40–49 years have hearing thresholds that are at least 20 dB more sensitive at 20 kHz than that of the average 30–39 year old. Moreover, 5% of the 5–19 year age group is reported to have a 20 kHz threshold that is 60 dB more sensitive than the median for the 30–39 year age group"
"For over 40 years, there have been reports of hearing threshold shift . . . and a range of subjective effects (nausea, dizziness, migraine, fatigue, tinnitus and ‘pressure in the ears’ . . .) from ultrasound in air to which workers have been routinely exposed (plus other symptoms that have not occurred in more than one study . . .). The degree of response, from significant to none, varied between workers. The evidence base has not studied sufficient numbers of subjects, and has not been sufficiently sensitive to the presence of sensitive individuals, or sensitive subgroups, within the population, to support the guidelines required today. Studies focused on occupational exposure to ultrasound, which tends also to occur alongside high levels of audible sound, and the effect of this audio frequency noise on the observed effects must be isolated because there is increasing public exposure to ultrasound without such audible cues. Measurement methods and audiological procedures in the past have tended to follow extrapolations of methods used in the audio frequency range which, alongside the calibrations and allowed tolerances of the equipment used, must be critically examined . . . . It is therefore no simple matter to measure the very high frequency/ultrasonic (VHF/US) fields to which people are exposed, either in situ or during audiological testing, and relate those to the levels quoted in past studies. Consequently, the evidence to date has been wholly inadequate to inform the development of guidelines for the increasing exposure of the public to ultrasound in air, and is suspect for occupational exposure."
Leighton, T. G. (2017). Comment on ‘Are some people suffering as a result of increasing mass exposure of the public to ultrasound in air?’. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 473(2199), 20160828.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 07/11/2023, 11:33
Leighton, T. G. (2018). Ultrasound in air: Guidelines, applications, public exposures, and claims of attacks in Cuba and China. The Journal of the Acoustical Society of America, 144(4), 2473–2489.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 29/11/2022, 07:35
Leighton, T. G. 2019, September 9–13. Ultrasound-in-air: New applications need improved measurement methods and procedures, and appreciation of any adverse effects on humans. Paper presented at 23rd International Congress on Acoustics.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 29/11/2022, 09:47
Leighton, T. G. 2020, December. Ultrasound in air: Experimental studies of the underlying physics are difficult when the only sensors reporting contemporaneous data are human beings. Physics Today, 38–43.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 07/11/2023, 12:31
Leighton, T. G., Currie, H. A. L., Holgate, A., Dolder, C. N., Jones, S. L., & White, P. R., et al. 2019, July 7–12. Analogies in contextualizing human response to airborne ultrasound and fish response to acoustic noise and deterrents. Paper presented at 5th International Conference on the Effects of Noise on Aquatic Life, Den Haag, The Netherlands.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 07/11/2023, 12:24
Leighton, T. G., Lineton, B., Dolder, C., & Fletcher, M. D. (2020). Public exposure to airborne ultrasound and very high frequency sound. Acoustics Today, 16(3), 17–26.
Added by: Mark Grimshaw-Aagaard Last edited by: Mark Grimshaw-Aagaard 06/12/2022, 09:58
Provides a map of London showing peaks in the range 17.4–22.4kHz measured c.2017 by public smartphones (Fletcher et al. 2018).