This diagram shows how loud certain frequencies must be in order for people of different ages to hear them. The needed intensity is called the "hearing level."

Question

A graph with age in years on the x axis from 20 to 70 and hearing level in decibels from 30 to 0. There are 5 graphs that are arcs that all start from point (25, 0) and end at points (70, 10), (70, 14), (70, 15), (70, 20), (70, 25) and (67, 35) and are labeled 500 Hertz, 1000 Hertz, 2000 Hertz, 3000 Hertz, 4000 Hertz and 6000 Hertz respectively.
According to the graph, what is the maximum age at which a 4000 Hz sound wave with an intensity of 20 dB would be heard?

55
60
65
70

Answer 1

To determine the maximum age at which a 4000 Hz sound wave with an intensity of 20 dB would be heard, we need to refer to the graph that corresponds to the 4000 Hz frequency. The graph for 4000 Hz ends at point (70, 25), which implies that at age 70, a sound wave with an intensity of 25 dB is the threshold.

Since we're looking for the age when a sound wave of 20 dB can be heard, we can observe the arc of the 4000 Hz line to see at what age it intersects the 20 dB level.

By visual inspection or estimation from the information given, the graph would indicate that the hearing level for 4000 Hz is 20 dB at an age around 60.

Therefore, the maximum age at which a 4000 Hz sound wave with an intensity of 20 dB would be heard is:

60