If you're eight minutes into a screaming row with your partner, it might be advisable to call an immediate truce.

Give it another 60 seconds and things could turn really ugly.

Researchers have found that the nine-minute mark is when marital arguments hit fever pitch.

Spouses' voices get increasingly shrill up to this point as the row intensifies. After that, they remain at the higher frequency.

However the phenomenon was only observed in couples in unhappy relationships. Those in contented marriages maintained their natural timbre, even at the peak of their disagreements.

Researchers have found that the nine-minute mark is when marital arguments hit fever pitch (Stock image)

Researchers say couples could use the pitch, as opposed to the volume, of a partner's voice to know how irate they are getting. 

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They also found that 'a person's return to normal can be facilitated by their partner – they calm down faster if the partner remains calm'.

Professor Melanie Fischer, who led the study, said: 'Once partners get more and more upset, they can't communicate well any more and might say things they later regret. 

'So it could be helpful for couples to note when they or their partner are getting increasingly upset, and when voice pitch goes up, and take a break from the argument to calm down.'

Her team at Philipps University of Marburg in Germany listened to hours of tapes from 404 couples – almost all of them married – to reach their conclusion. 

Their ages ranged from 20 to 85 and they were recorded having conversations of up to 15 minutes about concerns within the relationship.

Researchers say voice frequency is an indication of how het up – or 'emotionally aroused' in their jargon – people are getting. 

Researchers say couples could use the pitch, as opposed to the volume, of a partner's voice to know how irate they are getting (Stock image)

They concluded: 'Distressed couples may experience challenges communicating effectively as both partners become increasingly upset, and are only able to stop escalations in emotional arousal quite late. 

'Therefore, at least in the time frame explored here, they have little opportunity to address difficult issues while at their baseline of emotional arousal.'

The results were published in the scientific journal Behaviour Research And Therapy.