Sherlock Holmes stars Jeremy Brett (r) as the sleuth
Eight advertisements shown during an episode of Sherlock Holmes were so loud that they breached regulations, the industry watchdog has ruled.
The Advertising Standards Authority ruled that the slots on digital channel ITV3 were "excessively strident".
But it said complaints about noisy advertisements have gone down since rules were tightened two years ago.
ITV3 said the series was made in the 1980s and had many silent pauses so the commercials seemed louder.
But the watchdog upheld a complaint from a viewer about eight adverts during a break.
It ruled: "We noted that the programme had a wide dynamic range, with periods of quiet suspense punctuated by short, louder bursts.
"We noted that the maximum subjective loudness of ads was consistent with other ads during the break, but that it was not well matched to the overall sound levels of the programme."
But it recognised that ITV3, along with other broadcasters, were now working harder to keep noise levels down.
ITV3 said all their adverts were checked against a loudness meter and believed the loudness of the ones in question were "appropriate and consistent in the context of the overall loudness of the channel".
But it recognised there might have been an issue with the programme material.
Since television began, viewers have often complained about advertisements being louder than the programmes.
In response to complaints down the years, the broadcasting watchdog published a new rule on sound levels in 2008.
The Broadcast Committee of Advertising Practice, which is responsible for writing the TV Advertising Code, said "advertisements must not be excessively noisy or strident".
"The maximum subjective loudness of advertisements must be consistent and in line with the maximum loudness of programmes and junction material," it said.
The ASA received 100 complaints about perceived sound imbalances between programmes and advertisements in 2007. In 2009, there were just 45 complaints.
In the US, the House of Representatives recently passed a bill to curb loud advertisements.