A method of processing an audio signal comprising: obtaining a predetermined number of target gains for a first portion of the audio signal by analyzing the first portion of the audio signal, each of the target gains corresponding to a subband of the audio signal; determining filter coefficients for a time-domain filter for filtering the first portion of the audio signal so as to approximate a frequency response given by the obtained target gains, the filter coefficients determined by iteratively: selecting at least one target gain from the target gains, the selecting comprising: for a first target gain from the target gains for the first portion, determining a difference between the first target gain and a second target gain for a second portion of the audio signal, the second portion being prior to the first portion, the first and second target gains being corresponding to a same subband, and selecting the first target gain in response to the difference exceeding a predetermined threshold; updating the filter coefficients once for each audio sample or for each group of consecutive audio samples, based on the filter coefficients of the previous iteration, determined based on a least square method, and the selected at least one target gain, wherein according to the least square method h LS = Pd, wherein h Ls represents the filter coefficients, P is a mapping matrix and d is a matrix representing a target frequency response and comprising the target gains such that the filter coefficients for audio sample n are calculated according to: h LS ( n) = h LS ( n - 1) + Σ i ∈ T d ( ω i, n) p i, wherein i ∈ T are the indexes i of the selected target gains T, d ( ω i, n) represents the target gain for a subband ω i and p i represents a part of the mapping matrix corresponding to the subband ω i; and filtering the first portion of the audio signal in time domain based on the determined filter coefficients. obtaining a predetermined number of target gains for a first portion of the audio signal by analyzing the first portion of the audio signal, each of the target gains corresponding to a subband of the audio signal; determining filter coefficients for a time-domain filter for filtering the first portion of the audio signal so as to approximate a frequency response given by the obtained target gains, the filter coefficients determined by iteratively: selecting at least one target gain from the target gains, the selecting comprising: for a first target gain from the target gains for the first portion, determining a difference between the first target gain and a second target gain for a second portion of the audio signal, the second portion being prior to the first portion, the first and second target gains being corresponding to a same subband, and selecting the first target gain in response to the difference exceeding a predetermined threshold; updating the filter coefficients once for each audio sample or for each group of consecutive audio samples, based on the filter coefficients of the previous iteration, determined based on a least square method, and the selected at least one target gain, wherein according to the least square method h LS = Pd, wherein h Ls represents the filter coefficients, P is a mapping matrix and d is a matrix representing a target frequency response and comprising the target gains such that the filter coefficients for audio sample n are calculated according to: h LS ( n) = h LS ( n - 1) + Σ i ∈ T d ( ω i, n) p i, wherein i ∈ T are the indexes i of the selected target gains T, d ( ω i, n) represents the target gain for a subband ω i and p i represents a part of the mapping matrix corresponding to the subband ω i; and filtering the first portion of the audio signal in time domain based on the determined filter coefficients. selecting at least one target gain from the target gains, the selecting comprising: for a first target gain from the target gains for the first portion, determining a difference between the first target gain and a second target gain for a second portion of the audio signal, the second portion being prior to the first portion, the first and second target gains being corresponding to a same subband, and selecting the first target gain in response to the difference exceeding a predetermined threshold; for a first target gain from the target gains for the first portion, determining a difference between the first target gain and a second target gain for a second portion of the audio signal, the second portion being prior to the first portion, the first and second target gains being corresponding to a same subband, and selecting the first target gain in response to the difference exceeding a predetermined threshold; updating the filter coefficients once for each audio sample or for each group of consecutive audio samples, based on the filter coefficients of the previous iteration, determined based on a least square method, and the selected at least one target gain, wherein according to the least square method h LS = Pd, wherein h Ls represents the filter coefficients, P is a mapping matrix and d is a matrix representing a target frequency response and comprising the target gains such that the filter coefficients for audio sample n are calculated according to: h LS ( n) = h LS ( n - 1) + Σ i ∈ T d ( ω i, n) p i, wherein i ∈ T are the indexes i of the selected target gains T, d ( ω i, n) represents the target gain for a subband ω i and p i represents a part of the mapping matrix corresponding to the subband ω i; and filtering the first portion of the audio signal in time domain based on the determined filter coefficients.