The only bird known to make use of infrasound (at about 20 Hz) is the western capercaillie. The hearing range of birds is from below 50 Hz (infrasound) to around 12 kHz, with maximum sensitivity between 1 and 5 kHz. The range of frequencies at which birds call in an environment varies with the quality of habitat and the ambient sounds.
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Average Cost. The average cost of professionally cleaning your carpets is 28 cents to 30 cents per square foot, according to 2010 data.This varies depending on whether you use a franchise/national chain or a local business.he cost of having a carpet cleaned is usually determined according to square footage. The average cost of professionally cleaning your carpets is 28 cents to 30 cents per square foot, according to 2010 data.