BBC One controller Charlotte Moore has admitted viewer complaints about sound in shows such as Happy Valley have been “a big issue”.
Speaking at The Voice of the Listener and Viewer conference in London on Tuesday, Ms Moore said the corporation takes the criticism “incredibly seriously”.
The second series of acclaimed drama Happy Valley, written by Sally Wainwright and starring Sarah Lancashire, drew impressive ratings and bowed out with a record overnight viewing figure of 7.4 million.
But its six-week run was marred by constant complaints from fans about poor sound quality, mumbling and the need for subtitles.
It is not the first time a BBC show has faced criticism of this nature – hundreds complained about the sound in dramas Quirke and Jamaica Inn in 2014.
Ms Moore said: “Sound has been a big issue, all of us want to make sure that sound levels are absolutely so people can hear the fantastic work we are doing.”
She admitted it would be “incredibly hard” to find the cause of problems with sound, but said new guidelines would be issued to programme makers.
“It is incredibly hard to get to the bottom of where things go wrong,” Ms Moore said. “It is often several different problems coming together. Sound is a very exact science.”
Speaking on BBC Breakfast recently, writer Wainwright said viewer complaints about the sound in Happy Valley were “bemusing”.
“When it leaves the (dubbing suite), the episode is perfect, technically, it’s perfect – it has to be,” she told presenters Dan Walker and Louise Minchin.
“There are certain standards that we have to meet, so as the series transmission went on we became more and more conscious of being in the dub and listening really carefully, trying to be objective about it.
“We watched it on all the hi-tech equipment, we all brought a very ordinary telly in to listen to it on that.”
She added: “I do find it bemusing (that) for every person that said ‘I can’t hear it’, there were as many people saying ‘I can hear it’.”
BBC director general Tony Hall also referenced sound issues earlier this month and said he took the matter “seriously”.