We work with our commercial partners to ensure audio levels are set at a certain level. If an issue crops up, advertisers are happy to work with us to fix it. More broadly speaking, ads can appear to be louder because the dynamic range is often compressed - there is less range between quiet and loud. This way ads can have a louder overall sound without exceeding maximum peak levels. Programmes are never really compressed as heavily – meaning they sound "quieter". They are also longer and have more variation than an ad. Think of a half hour show like Shortland Street, where scenes can vary from fiery arguments to whispered exchanges. If an energetic ad follows a quiet scene, it can stand out more for viewers. If you would like to let us know which ads have an excessive volume increase, you can advise us by following this link