| 摘要 |
An earphone has a casing, containing a speaker, the casing being adapted to fit within the outer ear of a user at the entrance to the ear canal of the user. The earphone can be used in a noise cancelling earphone system, with signal processing circuitry connected to the microphone and to the speaker. The signal processing circuitry is adapted to receive the ambient noise signal from the microphone, and to apply the ambient noise signal to a filter having a controllable amount of gain, for generating a noise cancellation signal for transmission to the speaker. The result is that, however the earphone is worn within the outer ear of a user, an amount of sound leakage lies within a predetermined range, such that the amount of gain to be applied by the signal processing circuitry falls within a relatively narrow range. |
