We can observe this through an example: Imagine we have a sound that is a 10 Db. The equation for this is: A more practical way to deal with intensity is to utilize the log scale.

The filter output is simply accessed across the resistor instead of the capacitor. A decibel is a ratio of the observed amplitude, or intensity level to a reference, which is 0 dB. Note that because the same resistor and capacitor were used, the cutoff frequency has not changed. A decibel value is based on the logarithm of the intensity of a sound. Below is a Bode plot of the high-pass RC filter frequency response a few sections back.The cutoff frequency, which is 1592 Hz for this particular circuit, corresponds to a 3 dB attenuation, and can be used as a figure-of-merit for the response of the filter. This is the cutoff frequency, f 0, of the RC filter, which is expressed by the following relationship: f 0 = 1/(2πRC) Logarithmic scales are common, but often people are not shown how they work, why they are used, or when they are in use hence this post. The intersection point of these two lines coincides with the rounded section of the plot. The decibel scale cannot be a ‘linear scale’ we have already described that 120 dB must be much more than twice the sound level of 60 dB. Every Bode plot has two straight lines: the relatively flat response where little attenuation occurs and a linear response of -20 dB/decade at higher frequencies.Notice that low frequencies are unattenuated, but attenuation increases with higher frequencies. Loudness follows a logarithmic rather than a linear scale, so a sound measuring twice the level of another will not seem twice as loud. As opposed to a linear number line in which every unit of distance corresponds to adding by the same amount, on a logarithmic scale, every unit of length corresponds to multiplying the previous value by. Below is a Bode plot of the low-pass RC filter frequency response shown a few sections back. A logarithmic scale (or log scale) is a way of displaying numerical data over a very wide range of values in a compact way.

Decibel logarithmic scale