115-Decibels
"If someone managed to evade the infrared
detectors and got into the house, a 115-decibel siren would go off."
- Chapter 22, page 419
The energy in a sound wave can be measured using Decibels. The Decibel Meter shows examples of things that make noise and measurements in decibels.

Sound energy travels in waves and is measured in frequency and amplitude.
Amplitude measures how forceful the wave is.
It is measured in decibels or dBA of sound pressure.
0 dBA is the softest level that a person can hear.
Normal speaking voices are around 65 dBA.
A rock concert can be about 120 dBA.
Needless to say, Lisbeth is determined to not let any intruder go unnoticed. Any unwanted visitor will be heard at the level of a rock concert.
Amplitude measures how forceful the wave is.
It is measured in decibels or dBA of sound pressure.
0 dBA is the softest level that a person can hear.
Normal speaking voices are around 65 dBA.
A rock concert can be about 120 dBA.
Needless to say, Lisbeth is determined to not let any intruder go unnoticed. Any unwanted visitor will be heard at the level of a rock concert.