I would like to point out that Guttman and Julesz ("Lower Limits of
Auditory Periodicity Analysis", Letters to the Editor, JASA, Vol.
35(4), p. 610 (1963)) used periodic signals, consisting of repeated
wide-band noise with repetition periods corresponding to frequencies
in the low/infrasonic region. There was no fundamental in their signal,
thus no low-frequency/infrasonic exposure at all.
I agree that repetition frequency and frequency contents can easily be mistaken. In assessments of environmental noise, it is not unusual that a signal of higher frequency repeated with an infrasonic frequency is - erroneously - attributed to infrasound. Examples are broadband ventilation noise that is amplitude modulated by a low frequency, or sources of tonal noise with close frequency that cause beating at a low frequency. However, the sensation is completely different, whether the fundamental is there or not.
Henrik Møller Professor Section of Acoustics, Department of Electronic Systems Aalborg University Fredrik Bajers Vej 7 B5 DK-9220 Aalborg Ø, Denmark Phone: +45 9940 8711 (direct) Phone: +45 9940 8710 (section office) Phone: +45 9940 9940 (switchboard) Fax: +45 9815 2144 (section office) mailto:hm@xxxxxxxxxxxxxxxx (personal) mailto:acoustics@xxxxxxxxxxxxxxxx (section office) http://acoustics.aau.dk
Richard M. Warren skrev: