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Low-frequency noise A biophysical phenomenon Dr Mireille Oud medical physicist / consultant (Congress “Sound, Vibrations, Air quality, Field & Building”,

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Presentation on theme: "Low-frequency noise A biophysical phenomenon Dr Mireille Oud medical physicist / consultant (Congress “Sound, Vibrations, Air quality, Field & Building”,"— Presentation transcript:

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2 Low-frequency noise A biophysical phenomenon Dr Mireille Oud medical physicist / consultant (Congress “Sound, Vibrations, Air quality, Field & Building”, 6 November 2012, Nieuwegein, The Netherlands) 1 of 16

3 ContentsContents l Sources low-frequency sound l Biophysics perceptibility (neurobiologist A.N. Salt, Washington University) l Health effects l Conclusions l Advices l References 2 of 16

4 Via air: up to 1 km Sources low-frequency sound (<<150 Hz) Via ground: up to 100 km  cumulation sources l l Wind turbines l l Gas transport l l District heating l l Industry l l Difference tones l l … (Ref.: Kohlhase 2011) 3 of 16

5 Sources low-frequency sound Wind turbinesGas grid (Ref.: Kennisportal Wind energy)(Source.: 4 of 16

6 Biophysics perceptibility Cochlea ___  ______  Organ of balance (Ref.: Prasad)(Ref.: Chittka & Brockmann 2005) 5 of 16

7 Biophysics perceptibility Cochlea __________ l l Outer hair cells: pre-amplifier l l Inner hair cells: to brain (Ref.: Madhero88) (Ref.: Encyclopaedia Brit. 1997) 6 of 16

8 Biophysics perceptibility test animal l l Can become audible l l Audible for every- one (Ref.: Pedersen 2008) (Ref.: Salt 2011) 7 of 16

9 Biophysics perceptibility l l Occlusion helicotrema  20dB increase sensitivity for low frequencies l l Endolymfatic hydrops (swelling middle tube)  dizziness (Ref.: OpenLearn LabSpace)(Ref.: Salt & Lichtenhan 2012) 8 of 16

10 Biophysics perceptibility l Audible cochlea-activity (500 Hz) interacts with inaudible cochlea-activity (5 Hz)  low tone audible through amplitude modulation response cochlea test animal audible 5 Hz 5 Hz 500 Hz (Ref.: Salt & Lichtenhan 2011) 9 of 16

11 Biophysics perceptibility l l Low frequencies audible for everyone: beat, difference tone Superposition of nearly equal, audible, tones (a and b) this amplitude modulation can be acoustic (c) and neural (d) (Useful application: tuning musical instrument) a. mono 220 Hz b. mono 222 Hz c. mono Hz d. stereo: left 220, right 222 (Source: M. Oud 2012)  (Click here, in presenting mode of powerpoint. Use head phone.) 10 of 16

12 Biophysics perceptibility G-weighting: ISO 7196:1995 (Ref.: Cedric 2004) l l  dBC and dBG more realistic weighted wind-turbine spectra (Ref.: Van den Berg 2006) 11 of 16

13 Health effects l l Still more people perceive LFN (hearing / feeling) l l Health effects LFN: Dizziness Continuous, pulsing pressure on head Disturbed sleep Stress Raised blood pressure Heart rhythm disorders … 12 of 16

14 Health effects Why is low-frequency sound experienced as nuisance? l Directionless, lacks spaciality  seems “within the head” l Character (monotonous or pulsing) & duration l Lack of autonomy (uncontrollable): ear plugs no effect: entrance is via bone conduction l Affects physiology (structure cochlea) 13 of 16

15 ConclusionsConclusions l l Perception low-frequency sound been demonstrated objectively (audiograms) l l Perception low-frequency sound biophysically explicable l l Significant part NL-population experiences damage l l Low-frequency sound requires different way of assessment: minimally dBC instead of dBA, preference dBG 14 of 16

16 AdvicesAdvices l l Systematic investigation health issues l l More scientific research (medicine & physics) l l Defining measurement and assessment methodology l l Formulate norms for low-frequency sound l l International approach l l Makes sources low-frequency restricted l l Adjustment home environment? 15 of 16

17 ReferentiesReferenties l Dutch low-frequency noise vigilance group: l Dr Mireille Oud: l Prof. A.N. Salt: l ISO norm dBG: (ISO.org) and (DiracDelta science eng. enclyclopedia)http://tiny.cc/ISO1http://tiny.cc/ISO2 l Berg, G.P. van den (2006), “The sound of high winds: the effect of atmospheric stability on wind turbine sound and microphone noise” Ph.D. thesis, Biomed. eng. dept. Rijksuniversiteit Groningen l Cedric R. (2004), “Ecoaccess guideline for the assessment of low frequency noise“, Proc. of Acoustics 2004, 619– 624, Gold Coast, Australia l Chittka L, Brockmann A (2005) Perception Space – The Final Frontier. PLoS Biol 3(4): e137. doi: /journal.pbio l Encyclopaedia Britannica (1997) “Cochlea” l Kennisportal Wind energy on land (2011), “Bestaande windparken”, Min. Infrastructuur and Environment e.a. l Kohlhase S (2011), “Explaining buried pipeline induced LFN hum and gas turbine flutter …” Brookfield Ct, USA l Madhero88: l OpenLearn Labspace, “Hearing – section 3.3 The role of the basilar membrane in sound reception” l Pedersen C.S. (2008), “Human hearing at low frequencies with focus on noise complaints”, Ph.D. thesis, Acoustics dept. of elec. systems, Aalborg University, Denmark l Prasad, “Mechanical cochlea”, senior design project, Stevens Inst. Techn. l Salt A.N. (2011), “Processes underlying homeostasis of cochlear fluids”, Washington univ. l Salt, A.N. & Lichtenhan J.T. (2011), “ Responses of the inner ear to infrasound”, 4th Int. meeting on wind turbine noise, Rome l Salt, A.N. & Lichtenhan J.T. (2012), “Perception-based protection from low-frequency sounds may not be enough”, inter.noise 2012 New York 16 of 16


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