1. A comfort noise generation apparatus comprising: a near-end speech detector arranged to detect speech activity in a near-end signal; a far-end silence detector arranged to detect speech activity in a far-end signal; an acoustic echo canceller arranged, responsive to the far-end signal, to estimate an acoustic echo of the far-end signal within the near-end signal and output a modified near-end signal, the modified near-end signal representing the near-end signal after removing a copy of the estimated acoustic echo from the near-end signal; and a comfort noise generator, wherein responsive to an indication from the near-end speech detector that speech activity is absent on the near-end signal and an indication from the far-end silence detector that speech activity is absent on the far-end signal, the comfort noise generator is arranged to initiate a determination of an estimation of near-end background noise, the estimation responsive to the near-end signal, wherein responsive to an indication from the near-end speech detector that speech activity is present on the near-end signal or an indication from the far-end silence detector that speech activity is present on the far-end signal, the comfort noise generator is arranged to terminate the determination of an estimation of near-end background noise, wherein the comfort noise generator is arranged to output a function of the near-end background noise estimation, and wherein the initiation of the determination of an estimation of near-end background noise comprises an initiation of an update of a previous background noise estimation, the update comprising a predetermined function of the modified near-end signal and the previous background noise estimate.