The acoustical spectrum is usually divided into two major segments: that which can be heard by the human ear, and that which cannot, Moreover, it is usually maintained that if acoustical phenomena do not hurt the ear, that they will have no other bodily effects. In the electromagnetic (E&M) spectrum, there is also a segment capable of being perceived by human senses: visible radiation (light). However, unlike the acoustical spectrum, the E&M spectrum is not crudely divided in what is visible to the human eye, and what is not, nor is it assumed that E&M phenomena only cause bodily damage when they are seen. This is why it is possible to establish dose-responses for many different types of radiation (visible or not). A similar stance regarding the acoustical spectrum is required if dose-responses to infrasound & low frequency noise (ILFN <500 Hz) are genuinely desired. This report focuses on information gathered over the past 27 years of research into the biological effects of ILFN exposure, with the goal of contributing to the establishment of ILFN dose-response. A more detailed segmentation of the acoustical spectrum is proposed in order to adequately characterize acoustical environments.
BIOLOGICAL RESPONSES TO ILFN
The pathology that develops as a consequence of excessive ILFN exposure is called vibroacoustic disease (VAD). For the past 27 years, the authors have been part of the multi-disciplinary team of researchers who have studied the biological effects of ILFN exposure in humans and animal models, as well as the clinical manifestations of VAD in humans. Resonance frequencies of the different tissues and organs play a significant role in the biological response to ILFN, as would be expected of any vibratory phenomena interacting with a substance. Specific features of cellular, tissue and organ responses to ILFN exposure, such as mechanotransduction (for example), are essential to understanding how to establish dose-responses to ILFN.