例句與造句

1. Active noise cancelling headphones were invented by Lawrence J . Fogel, an aerospace engineer working to improve communication in helicopter cockpits, with a patent filed April 2, 1954.
2. Active noise cancelling headphones can attenuate ambient noise by 20 dB or more, but the active circuitry is mainly effective on constant sounds and at lower frequencies, rather than sharp sounds and voices.
3. It's difficult to find active noise cancelling in a sentence. 用active noise cancelling造句挺難的