Final answer:
Without specific context, it's not possible to determine where a 15 dB difference in frequency occurs, but high frequencies generally experience more significant decibel variation.
Step-by-step explanation:
The range of frequencies that humans can hear is from 20 Hz to 20,000 Hz. Sounds above 20,000 Hz are known as ultrasound, while those below 20 Hz are called infrasound. Regarding the question about the frequency range where there is a difference of almost 15 dB, without specific context or a reference to a diagram or data set, it is not possible to accurately determine whether this difference occurs at low, mid, high, or ultrasonic frequencies. However, in general, higher frequencies tend to be absorbed more easily and can show more significant variation in decibels over shorter distances or between different environments compared to lower frequencies. Additionally, the human ear's sensitivity varies with frequency, typically being less sensitive at very low and very high frequencies. As such, the exact scenario where a 15 dB difference occurs would rely on several factors including the environment, the sound's source, and the measuring equipment.