An audio decoder for providing a decoded representation of an audio content on the basis of an encoded representation of the audio content, the audio decoder comprising: a linear-prediction-domain decoder core configured to provide a time-domain representation of an audio frame on the basis of a set (226, 232, 228) of linear-prediction domain parameters associated with the audio frame; a frequency-domain decoder core configured to provide a time-domain representation of an audio frame on the basis of a set of frequency-domain parameters, taking into account a transform window out of a set comprising a plurality of different transform windows (310, 320, 324, 330, 340, 350, 360, 364, 370, 380, 384); and a signal combiner configured to overlap-and-add time-domain representations (252, 262) of subsequent audio frames encoded in different domains, in order to smoothen a transition between the time-domain representations of the subsequent frames; wherein the set of transform windows available for application by the frequency-domain decoder core comprises an insertion window (384,stop_start_window_1152_to_LPD) adapted for a generation of a time-domain representation of a single frequency-domain encoded audio frame temporally embedded between a preceding audio frame encoded in the linear-prediction domain and a subsequent audio frame encoded in the linear-prediction-domain, wherein a left-sided transition slope of the insertion window (384,stop_start_window_1152_to_LPD) is adapted to provide for a smooth transition between a time-domain representation of the preceding frame encoded in the linear-prediction domain and the time-domain representation of the single frame encoded in the frequency-domain, and wherein a right-sided transition slope of the insertion window (384, stop_start_window_1152_to_LPD) is adapted to provide for a smooth transition between the time-domain representation of the single frame encoded in the frequency-domain and a time-domain representation of the subsequent frame encoded in the linear-prediction domain; wherein the audio decoder comprises a decoder/inverse quantizer/rescaler configured to receive an encoded spectral value information, to decode the encoded spectral value information, to perform an inverse quantization of the decoded spectral value information, and to perform a rescaling by applying scale factors or inverse scale factors to the decoded and inversely quantized spectral value information, to obtain the set of frequency-domain parameters. a linear-prediction-domain decoder core configured to provide a time-domain representation of an audio frame on the basis of a set (226, 232, 228) of linear-prediction domain parameters associated with the audio frame; a frequency-domain decoder core configured to provide a time-domain representation of an audio frame on the basis of a set of frequency-domain parameters, taking into account a transform window out of a set comprising a plurality of different transform windows (310, 320, 324, 330, 340, 350, 360, 364, 370, 380, 384); and a signal combiner configured to overlap-and-add time-domain representations (252, 262) of subsequent audio frames encoded in different domains, in order to smoothen a transition between the time-domain representations of the subsequent frames; wherein the set of transform windows available for application by the frequency-domain decoder core comprises an insertion window (384,stop_start_window_1152_to_LPD) adapted for a generation of a time-domain representation of a single frequency-domain encoded audio frame temporally embedded between a preceding audio frame encoded in the linear-prediction domain and a subsequent audio frame encoded in the linear-prediction-domain, wherein a left-sided transition slope of the insertion window (384,stop_start_window_1152_to_LPD) is adapted to provide for a smooth transition between a time-domain representation of the preceding frame encoded in the linear-prediction domain and the time-domain representation of the single frame encoded in the frequency-domain, and wherein a right-sided transition slope of the insertion window (384, stop_start_window_1152_to_LPD) is adapted to provide for a smooth transition between the time-domain representation of the single frame encoded in the frequency-domain and a time-domain representation of the subsequent frame encoded in the linear-prediction domain; wherein the audio decoder comprises a decoder/inverse quantizer/rescaler configured to receive an encoded spectral value information, to decode the encoded spectral value information, to perform an inverse quantization of the decoded spectral value information, and to perform a rescaling by applying scale factors or inverse scale factors to the decoded and inversely quantized spectral value information, to obtain the set of frequency-domain parameters.