Jenny....I have looked, but cannot find the one to which you are referring.
However....you need more than sound levels to understand what people are saying you need speech appreciation ( speech discrimination).....in simple terms, if you cannot understand what people are saying there is not much point in speech volume.Sound(noise)is mainly appreciated in the low tones, but speech discrimination (understanding) is usually provided by vowels, which are in the high tones.
NOW....many nerve deafness's are in the high tones much more than the lower tones which means that sound is fine, but discrimination (speech) is poor.
Simply put........you can hear them talking, but you cannot understand what they are saying.
Is that simple explanation helpful?