Nitro-. a combining form or an adjective denoting the presence of niter. Nitro-. a combining form (used also adjectively) designating certain compounds of nitrogen or of its acids, as nitrohydrochloric, nitrocalcite; also, designating the group or radical NO2, or its compounds, as nitrobenzene.
The commonly stated range of human hearing is 20 Hz to 20 kHz. Under ideal laboratory conditions, humans can hear sound as low as 12 Hz and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea.
Normal human hearing ranges from 20 hertz to 20,000 hertz. Low-frequency sounds, below 20 hertz, are referred to as âinfrasoundâ and travel farther than high-frequency sounds. Frequencies above the range of human hearing (20,000 hertz) are referred to as âultrasonic.â.lthough the upper end of human hearing is about 20,000 hertz, deer can hear frequencies to at least 30,000 hertz. But, these high-frequency sounds must be louder because high-frequency sounds donât travel as far as low-frequency sounds. Hearing and Vocal Communication.