Turn on the radio or tv, loud enough so that we'll be hearing how his speech clearly who will wear the headphones, because it will make us hear the pronunciation of each word clearly to him in good.
Turn on the radio or television to sound loud enough. In order for us to hear how his speech clearly. Or who was wearing headphones. Because we hear the pronunciation of each word clearly.
Turn on the radio or television loud enough. So that we can hear his way of speaking clearly, or who wear headphones. Because we will hear his pronunciation of each word clearly.