騒音 | Usually used like this:都市の騒音 (the din of the big city). 騒音 does not refer to specific noises, but the general teeth-grinding day-in-and-day-out sonic stress from 1,000 sources:street construction, honking horns, loudspeaker announcements, shopkeepers yelling at passers-by, screeching trains, etc. |
雑音 | Most Westerners use this when they should be using 騒音。 雑音 is only used in science:signal-to-noise ratio. The surface noise of an old vinyl record. Static noise on the radio. Noise in the narrow sense of something that interferes with a specific signal. |