Nothing is known of Dr. Anton Decibel's early life, aside from the fact that he supposedly became a medical doctor, before being lured into a life of crime. At some point after becoming a criminal, he altered Linda Lewis's vocal chords so that she could produce a hypersonic scream. His motives for doing this are unknown, although as she was a popular and well-known singer, it is possible that he did it out of jealousy of her fame, or out of spite. At some point Dr. Decibel joined the Institute of Evil, as part of a game between the Grandmaster and the Scarlet Centurion, to fight the Squadron Supreme.
Dr. Decibel was created by Mark Gruenwald and Bob Hall, and first appeared in Squadron Supreme #5 as a member of the Institute of Evil. Dr. Decibel is inspired by Sonar, master of sound and one of Green Lantern's more formidable foes back when the Squadron Supreme limited series was first published (although he has fallen into obscurity in the years since then and gone from a competent foe who occasionally defeated Green Lantern to a joke character with little skill beyond bluster).
Dr. Decibel first appeared as a somewhat sinister doctor in the Institute of Evil, prior to being put under a Behaviour Modifier ("B-Modder") machine by the Squadron Supreme. Afterwards, just like the rest of the Institute, he was friendly and no longer evil. Although Dr. Decibel was rarely seen, he appeared to be quiet and studious, becoming the team's medical doctor.
Major Story Arcs
The Utopia Principle
Several months after the Squadron Supreme announced their plan to turn Earth into a utopia, Dr. Decibel was with the rest of the Institute of Evil when they captured the Golden Archer and found out about Tom Thumb's recently invented Behavior Modifier machine. The Institute then captured several of the Squadron's friends and family, as the Squadron members had all recently unmasked, and attempted to use that as leverage against the team. The Squadron instead attacked the Institute, but were unsuccessful in defeating them. During the fight, Dr. Decibel fought and defeated Lady Lark, as he was immune to her sonic powers. The Institute then B-Modded the Squadron to become evil, but unfortunately for them they didn't realize that Tom Thumb had built a fail safe into the B-Modder so that no Squadron members could be affected by it. As a result, the Squadron sprung a surprise attack on the Institute, and this time they were successful.
The Squadron then used the B-Modder on the Institute of Evil so that they couldn't commit any more crimes or betray the Squadron Supreme. With this done, they could afford to have the ex-Institute members join and increase their ranks. After joining, Dr. Decibel spent most of his time as the team's medical doctor, mostly overseeing Arcanna's pregnancy. Towards the end of the Squadron's reign,Quagmire was rendered in a coma thanks to some gas he had inhaled whilst saving some factory workers. Whilst Dr. Decibel was watching over Quagmire, he noticed some extra-dimensional slime, which Quagmire could produce as a result of his powers, beginning to appear, showing that Quagmire's higher brain functions were returning. Unfortunately, the slime kept appearing at an alarming rate, eventually flooding the entire hospital. Dr. Decibel didn't escape in time, and was suffocated before Quagmire could be stopped.
Powers and Abilities
Dr. Decibel had a device which could produce up to 300 decibels of sound, which he primarily used as an attack. He was also a skilled surgeon, notably altering Linda Lewis's vocal chords in order to give her super powers. He also was the Squadron's medical doctor whilst he was a member, so it can probably be assumed that he had a medical certificate and was a fully qualified doctor.
Having been Behavior Modified by the Squadron, the ex-Institute of Evil members are unable to break the law for any reason, betray any Squadron member for any reason. Their minds are no longer truly their own.
No alternate versions of Dr. Decibel have been seen, at time of writing.