Dutch bells got hoarse. The reason is simple: air pollution and subsequent acid rains. Corrosion leaves cavities and furrows on the bell faces which alters their original sound by adding jar (i.e. dissonance) to music. Holland and Belgium are famous for performing bell polyphony. And now the music sounds out of tune. Tourists may not notice that. But can they understand how the local residents, accustomed to former harmony, find the “hoarse” ringing?