Current is measured in Amperes, Potential difference in Volts.
why don't AC currents from 'LV' phone affect adjacent speaker wires?
Magnetic flux is directly proportional to current.
The current flowing when the phone rings is small, very little magnetic flux.
Speakers are low impedance devices, inducing enough curreent into a low impedance circuit to be audible is very difficult.
A related question - why don't AC currents from 'LV' phone affect adjacent speaker wires? The phone AC current jumps to 90 VAC, while ringing.
Both phone cord and speaker wire are packaged so that each pair is parallel and very close together. This rejects common mode noise, and keeps EM emissions to practically zero. Unless that phone cable is driving a high REN load, the amount of power is miniscule. A cordless phone base of the type that is common with whole house cordless products has a REN that's 1/10th that of an old Western Electric phone. Besides, how often does the phone ring?
If the phone ringing made a noise that I could hear through my speakers, I'd call that a feature!
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