Sound Level Change in Decibels Perception 3 Barely perceptible 5 Clearly perceptible 10 Twice as loud Note that the sound level scale in decibels is a logarithmic rather than linear scale.A sound level change of 3 decibels is double (or half) of the previous power level. The ear registers this as just noticeable. A change in power level of 10n decibels is a power change of 10 times, and the ear judges this as only twice (or half) as loud. These relationships do not hold true at all power levels or at all frequencies, as the ear is a very non-linear device. See Fletcher-Munson hearing curves published in books on hearing. Some human ears can hear sounds in the frequency range of 20Hz to 20,000Hz, however, the hearing for most people is limited to about 30Hz to 15,000 Hz.