Likewise our hearing does not have the same sensitivity at all frequencies. No microphone has the same sensitivity to all frequencies and no speaker reproduces all frequencies equally well, as we will see in Chapter 18 on electronics. The above curves are very much like the frequency response curves of microphones and speakers. Medium loudness doesn't change the perceived pitch very much. For this reason, Decibels are displayed Logarithmically, which basically means that Decibels get exponentially bigger as they go up the scale. A sound 1,000 times more powerful than near total silence is 30 dB. A sound 100 times more powerful than near total silence is 20 dB. It's a logarithmic scale, so a sound 10 times more powerful is 10 dB. Low frequencies are perceived to be slightly lower than expected if they are very loud. Decibels describe the relationship between two units of power and the units of power that they are in relation to, can cover a huge range. On the decibel scale, the smallest audible sound (near total silence) is 0 dB. High frequencies are perceived to be a slightly higher pitch than normal if they are very loud. This is a way of counting or measuring something that increases rapidly, or exponentially.
It is also the case that intensity has an effect on perceived frequency the same laboratory frequency will appear to be a slightly different frequency if the intensity is different. Decibel is a unit of measurement that expresses the logarithmic ratio of two physical quantities of the same dimensions. If you do anything with ultrasound, you will notice that the measurements are in dB, but what does that mean Jason Tranter explains the dB scale and how to. \( \newcommand\) is due to the tube resonance of the auditory canal (see chapter 12 for tube resonance and chapter 10 for a picture of the auditory canal).