London - Getting a sullen teenager to tidy their room can prove an impossible task.
But there may be help for frustrated parents, as researchers say the key to success lies in your tone of voice.
Mothers speaking in a "controlling tone" were less likely to gain co-operation from children than when using a warm, friendly and supportive manner.
Speaking in a "pressurising" way would make a youngster feel gloomy, miserable, angry or emotionally distant – as well as being more likely to lead to defiance – the scientists found.
In the study, thought to be the first on how a mother’s tone of voice affects the response received, researchers examined 1 000 British boys and girls aged 14-15.
The study’s lead author Dr Netta Weinstein, of Cardiff University, said: "If parents want conversations with their teens to have the most benefit, it’s important to remember to use supportive tones of voice."
The study suggested teenagers were far more likely to engage with instructions that conveyed a sense of encouragement and support for self-expression and choice.
The results, while of obvious interest to parents, may also be useful to teachers.
Dr Weinstein added: "Adolescents likely feel more cared about and happier, and as a result they try harder at school, when parents and teachers speak in supportive rather than pressuring tones of voice."
In the study, published today in the journal Developmental Psychology, each youngster was randomly assigned to a group. Groups were then played identical messages delivered by mothers of teenagers who spoke in three different tones of voice. The voices were either controlling – imposing pressure and coercing the listener into action – neutral, or more supportive.
Each of the parents delivered 30 sentences that centred around school work, and included instructions such as: "It’s time now to go to school", "you will read this book tonight", and "you will do well on this assignment".
After hearing the messages, each student answered questions about how they would feel if their mother had spoken to them in that way.
Analysis of the teenagers’ responses showed that they were less likely to do the task being asked of them when spoken to in a controlling tone of voice, compared to when they were spoken to in a more supportive manner.
Study co-author Professor Silke Paulmann, of the University of Essex, added: "These results nicely illustrate how powerful our voice is and that choosing the right tone to communicate is crucial in all of our conversations."
The researchers now intend to study the impact of tone of voice on physiological responses such as heart rates – and how long lasting the effects may be.