How loud is a 3dB increase?
An increase of 3dB doubles the sound intensity but a 10dB increase is required before a sound is perceived to be twice as loud. Therefore a small increase in decibels represents a large increase in intensity. The sound intensity multiplies by 10 with every 10dB increase.
Half-power point. The half-power point or half-power bandwidth is the frequency at which the output power has dropped to half of its peak value; that is, at a level of approximately -3 dB.
- Half power point. The half power point of an electronic amplifier stage is that frequency at which the output power has dropped to half of its mid-band value. That is a level of -3 dB. This is therefore also known as the −3 dB bandwidth.
- The 3dB point, or 3dB frequency, is the point at which the signal has been attenuated by 3dB (in a bandpass filter). This is generally considered the point for determining the filter's bandwidth. The bandwidth is defined as the difference between the upper and lower 3dB points.
- The reasoning is simple. For any amplifier or a filter (low pass filters and band pass filters have a defined bandwidth), their gain falls with frequency as you will know. Hence the definition of bandwidth is the frequency at which the output signal's power becomes half of its maximum (which occurs at DC frequency).
Updated: 2nd October 2019