Since doctors and audiologists tend to under-estimate their patient’s ability to understand such things (or they don’t understand it themselves), the erroneous concept of dB = % evolved. If we forget about hearing losses greater than 100 dB (like most people tend to do), we get 0 dB to 100 dB as the usable (dynamic) range of hearing for the average ‘normal’ ear. To make a scale that makes sense to most people (including us knucklehead audiologists), a different equation is used to convert sound intensity using the Sound Pressure Level (SPL) scale to the Hearing Level (HL) scale that goes from 0 dB HL (normal threshold) to 120 dB HL (pain). To measure sound intensity (the way audiologists measure it) you need to do a mathematical calculation that is so strange that 20 + 20 = 26 dB (SPL). Where did the idea come from that we can measure hearing loss in percentages? Here is how Brad Ingrao, an outstanding audiologist, explained it. When people (ignorantly) talk about having a 50 percent hearing loss they likely mean that they have a 50 dB loss. They are as different as trying to compare apples to elephants! ![]() Numbers that appear to be similar have vastly differing meanings. Second, the decibel scale is logarithmic, while the percent scale is linear. Any attempt to do so is just a bunch of meaningless gibberish! ![]() Therefore, you cannot calculate a percentage. In both of these scales there is no limiting maximum value. To calculate a percent you need to know the maximum value possible. First, the decibel scale is open-ended like that of the Richter scale used for measuring earthquake intensities. There are two reasons why you can never equate decibels to percentages. Sound intensities are indeed measured in decibels (dB). ![]() You have good reason to be confused because you cannot equate decibels to percentages no matter what anyone tells you. Question: From time to time, I see people writing, “I have 78% hearing loss in my right ear and 95% in the left.” What does this percent mean? I thought sound was measured in decibels (dB), not percent? If this is the case what percent is 115 dB?-R.
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