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Question: audio-techica ath-anc7 earphones

I just bought a pair of Audio-Technica. I used them on 2 flights sitting in the exit aisle. I had the noise-cancelling function on. On a couple of occasions on both flights a static sound came through the right earphone. It lasted a few seconds or less. Just before it happened it sound like someone (pilot? or flight attendant?)turned on a device,(plane intercom? or something). Most of the time (99%) the earphones worked great. But it happened on both flights and under the same circumstances. Is this a defect in the earphone? The earphone was not plugged into any device and it had a brand new battery.
Thanks for any response.