Suppose a person is going to be exposed to a steady tone of frequency 8000 Hz all night (perhaps arising from noisy electronics in a nearby room. ) If this person wants their perceived room loudness level to be a very quiet 10 phon (in order to sleep easily), what is the maximum sound intensity level (in dB) that we should have in the room? Use Fig 6.12 to help you answer this question. Once again, you can round to the nearest 5 dB. Do not enter units. If you think the best answer is 13 dB, enter 15.
To determine the maximum sound intensity level (in dB) in the room, we need to use Figure 6.12, which shows the relationship between loudness level (in phon) and sound intensity level (in dB) for a 8000 Hz tone.
First, find the loudness level of 10 phon on the y-axis of Figure 6.12. Then, locate the corresponding sound intensity level on the x-axis. The point of intersection between the line for 8000 Hz and the 10 phon loudness level represents the maximum sound intensity level for a very quiet room of 10 phon.
According to Figure 6.12, the closest point of intersection for 8000 Hz and 10 phon is around 30 dB (you can round to the nearest 5 dB as instructed). Therefore, the maximum sound intensity level that should be present in the room is approximately 30 dB.