I would let nature do its thing.
Members above have pointed out that sooner rather than later, the predators are going to realise that sound coming from the radio doesn’t automatically mean people being present.
At the same time, the added noise coming from the radio is likely to confuse your chickens, which should be on the lookout for predators while foraging. Chickens already have a great warning system, which usually comes in the form of a senior rooster and/or the head hen.
When free ranging, losses are almost inevitable. Lots of cover and places to escape from predators such as branches, bushes, hedges, threes and undergrowth, as well as observant birds that can easily fly and run to safe locations are very helpful when free ranging