A computer system comprising: an audio processing module configured to process a first audio signal and output the processed first audio signal to audio output means of the system; an echo cancellation module configured to cancel echo resulting from the processed first audio signal from a second audio signal received via audio input means of the system; and a control module configured to detect a condition indicative of nonlinear amplitude processing by the audio processing module and control said echo cancellation by the echo cancellation module based on the detected condition, wherein: said control module is configured to, for each of the first audio signal and the received second audio signal, determine a parameter of an amplitude distribution for the respective audio signal among the first and received second audio signals, the distribution being a histogram, said detection comprising comparing the determined parameters for each distribution; and determining each of said respective distribution parameters for the respective distributions comprises at least one of: determining a weight parameter by comparing an upper portion of that distribution to a lower portion of that distribution, the weight parameter being a ratio between a respective upper and lower sum of bins of the histogram where each bin is a range of amplitude values, said detection comprising comparing the determined weight parameters for the respective distributions, or determining a percentile for that distribution, said detection comprising comparing the determined percentiles for the respective distributions. an audio processing module configured to process a first audio signal and output the processed first audio signal to audio output means of the system; an echo cancellation module configured to cancel echo resulting from the processed first audio signal from a second audio signal received via audio input means of the system; and a control module configured to detect a condition indicative of nonlinear amplitude processing by the audio processing module and control said echo cancellation by the echo cancellation module based on the detected condition, wherein: said control module is configured to, for each of the first audio signal and the received second audio signal, determine a parameter of an amplitude distribution for the respective audio signal among the first and received second audio signals, the distribution being a histogram, said detection comprising comparing the determined parameters for each distribution; and determining each of said respective distribution parameters for the respective distributions comprises at least one of: determining a weight parameter by comparing an upper portion of that distribution to a lower portion of that distribution, the weight parameter being a ratio between a respective upper and lower sum of bins of the histogram where each bin is a range of amplitude values, said detection comprising comparing the determined weight parameters for the respective distributions, or determining a percentile for that distribution, said detection comprising comparing the determined percentiles for the respective distributions. said control module is configured to, for each of the first audio signal and the received second audio signal, determine a parameter of an amplitude distribution for the respective audio signal among the first and received second audio signals, the distribution being a histogram, said detection comprising comparing the determined parameters for each distribution; and determining each of said respective distribution parameters for the respective distributions comprises at least one of: determining a weight parameter by comparing an upper portion of that distribution to a lower portion of that distribution, the weight parameter being a ratio between a respective upper and lower sum of bins of the histogram where each bin is a range of amplitude values, said detection comprising comparing the determined weight parameters for the respective distributions, or determining a percentile for that distribution, said detection comprising comparing the determined percentiles for the respective distributions. determining a weight parameter by comparing an upper portion of that distribution to a lower portion of that distribution, the weight parameter being a ratio between a respective upper and lower sum of bins of the histogram where each bin is a range of amplitude values, said detection comprising comparing the determined weight parameters for the respective distributions, or determining a percentile for that distribution, said detection comprising comparing the determined percentiles for the respective distributions.