An audio decoder (200; 800) for providing a decoded audio information (212; 812) on the basis of an encoded audio information (210; 810), the audio decoder comprising: an arithmetic decoder (230; 820) for providing a plurality of decoded spectral values (232; 822) on the basis of an arithmetically-encoded representation (222; 821) of the spectral values comprised in the encoded audio information (210; 810); and a frequency-domain-to-time-domain converter (260; 830) for providing a time-domain audio representation (262; 812) using the decoded spectral values (232; 822), in order to obtain the decoded audio information (212; 812); wherein the arithmetic decoder (230; 820) is configured to select a mapping rule (297; cum_freq[]) describing a mapping of a code value (acod_m, value) of the arithmetically-encoded representation (222, 821) of the spectral values onto a symbol code (symbol) representing one or more of the decoded spectral values or at least a portion of one or more of the decoded spectral values in dependence on a context state described by a numeric current context value (c); and wherein the arithmetic decoder (230; 820) is configured to determine the numeric current context value (c) in dependence on a plurality of previously decoded spectral values; wherein the arithmetic decoder is configured to obtain a plurality of context subregion values (q [i-1], q [i],q [i+1],q [i-1]) describing sub-regions of the context on the basis of previously decoded spectral values and to store said context subregion values; wherein the arithmetic decoder is configured to derive the numeric current context value (c) associated with one or more spectral values to be decoded in dependence on the stored context subregion values (q [i-1], q [i],q [i+1],q [i-1]); wherein the arithmetic decoder is configured to compute the norm of a vector formed by a plurality of previously decoded spectral values (a,b), in order to obtain one of said plurality of context subregion values as a common context subregion value (q [i-1]) associated with the plurality of previously decoded spectral values (a,b) based on which said norm is computed. an arithmetic decoder (230; 820) for providing a plurality of decoded spectral values (232; 822) on the basis of an arithmetically-encoded representation (222; 821) of the spectral values comprised in the encoded audio information (210; 810); and a frequency-domain-to-time-domain converter (260; 830) for providing a time-domain audio representation (262; 812) using the decoded spectral values (232; 822), in order to obtain the decoded audio information (212; 812); wherein the arithmetic decoder (230; 820) is configured to select a mapping rule (297; cum_freq[]) describing a mapping of a code value (acod_m, value) of the arithmetically-encoded representation (222, 821) of the spectral values onto a symbol code (symbol) representing one or more of the decoded spectral values or at least a portion of one or more of the decoded spectral values in dependence on a context state described by a numeric current context value (c); and wherein the arithmetic decoder (230; 820) is configured to determine the numeric current context value (c) in dependence on a plurality of previously decoded spectral values; wherein the arithmetic decoder is configured to obtain a plurality of context subregion values (q [i-1], q [i],q [i+1],q [i-1]) describing sub-regions of the context on the basis of previously decoded spectral values and to store said context subregion values; wherein the arithmetic decoder is configured to derive the numeric current context value (c) associated with one or more spectral values to be decoded in dependence on the stored context subregion values (q [i-1], q [i],q [i+1],q [i-1]); wherein the arithmetic decoder is configured to compute the norm of a vector formed by a plurality of previously decoded spectral values (a,b), in order to obtain one of said plurality of context subregion values as a common context subregion value (q [i-1]) associated with the plurality of previously decoded spectral values (a,b) based on which said norm is computed.