A method of modifying an audio signal, the method comprising: receiving the audio signal at signal processing means (202, 220, 222, 224, 230); analysing the received audio signal to identify characteristic signal components in the audio signal; generating an adjusted gain in dependence upon the signal strength of the identified signal components; determining that another, non-audio signal is input at an input means (116, 118) to the signal processing means, wherein the non-audio input signal is not an audio signal and is generated from an activity at said input means, and wherein said activity generates mechanical sound that contributes to noise in the audio signal; selectively applying the adjusted gain to the audio signal based on the determination that the non-audio input signal is input to the signal processing means, wherein when it is determined that the non-audio input signal is input to the signal processing means: applying an unadjusted gain to the audio signal instead of the adjusted gain, the unadjusted gain being the gain that has previously been generated in a pre-processor block based upon the signal strength of the identified speech components in previously received portions of the audio signal; or modifying the adjusted gain and applying the modified adjusted gain to the audio signal instead of the adjusted gain, wherein the modified adjusted gain is closer to the unadjusted gain than the adjusted gain is to said unadjusted gain. receiving the audio signal at signal processing means (202, 220, 222, 224, 230); analysing the received audio signal to identify characteristic signal components in the audio signal; generating an adjusted gain in dependence upon the signal strength of the identified signal components; determining that another, non-audio signal is input at an input means (116, 118) to the signal processing means, wherein the non-audio input signal is not an audio signal and is generated from an activity at said input means, and wherein said activity generates mechanical sound that contributes to noise in the audio signal; selectively applying the adjusted gain to the audio signal based on the determination that the non-audio input signal is input to the signal processing means, wherein when it is determined that the non-audio input signal is input to the signal processing means: applying an unadjusted gain to the audio signal instead of the adjusted gain, the unadjusted gain being the gain that has previously been generated in a pre-processor block based upon the signal strength of the identified speech components in previously received portions of the audio signal; or modifying the adjusted gain and applying the modified adjusted gain to the audio signal instead of the adjusted gain, wherein the modified adjusted gain is closer to the unadjusted gain than the adjusted gain is to said unadjusted gain. applying an unadjusted gain to the audio signal instead of the adjusted gain, the unadjusted gain being the gain that has previously been generated in a pre-processor block based upon the signal strength of the identified speech components in previously received portions of the audio signal; or modifying the adjusted gain and applying the modified adjusted gain to the audio signal instead of the adjusted gain, wherein the modified adjusted gain is closer to the unadjusted gain than the adjusted gain is to said unadjusted gain.