Noise SMA inverters and transformers produce a constant low-frequency hum , audible in the still countryside air. The valley naturally carries and echoes sound , so even moderate noise stands out more here than in flatter, built-up areas. Saying noise impact is “low” ignores how that level in this quiet valley feels intrusive — especially when echo amplifies it. The suggested acoustic fence is only a concept , with no real proof it would actually reduce the sound in our setting. 26