What are the lowest and highest frequencies that an ear can detect when the sound level is 40 dB? (See Fig. 12–6.)
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This is Giancoli Answers with Mr. Dychko. If we look at the lowest red line on this graph, that corresponds to the threshold of hearing. So, we want to see what frequency does the 40 decibel sound level cross this lowest red line. And that happens at about 80 hertz. So, that's the lowest frequency you could possibly perceive with a 40 decibel sound level. And the maximum doesn't cross the 40 decibel line, this line just sort of ends here at about 20,000 hertz. So, you can hear anything from 80 hertz to 20,000 hertz with a sound level of 40 decibels.
Hi, I could be completely wrong about this, but isn't it correct to say that at 40 db, when looking at the maximum frequency you can hear, you should be on the 20 phon line? I agree with you on the minimum - at 40 dB, the lowest frequency you can hear is 80 Hz. But they ask for the max frequency you can hear AT 40 dB...the 0 phon line does not cross 40 dB, but the 20 phon line does.
So shouldn't you look for the max frequency that crosses the 40 dB line - which would fall on the 20 phon line?
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