According to the World Health Organisation, Spain is the noisiest country in Europe, and Madrid is one of the noisiest capitals.
(In fact Spain is the second noisiest country in the world, behind Japan. Most of the noise comes from traffic, such as cars, heavy lorries and noisy motorbikes and mopeds. This is closely followed by building works, discotheques and leisure activities in general; especially in summer.
Having been to Valencia during Las Fallas, I’m sure fireworks, which are more like army ordnance, don’t help.)