A communication device comprising: a processor ; a source interface comprising a first source interface for a first external source and a second source interface for a second external source; a signal generation module comprising a first noise generator for generating one or more noise signals; and an output interface ; wherein the processor is configured to: obtain a first input signal via the first source interface ; obtain a first complementing signal based on one or more noise signals from the first noise generator ; combine the first input signal and the first complementing signal to a first combined signal ; apply a first filter function to the first combined signal for provision of a first left output signal and a first right output signal ; the first filter function comprising one or more head related transfer functions (HRTF_1_L, HRTF_1_R); obtain a second input signal via the second source interface ; obtain a second complementing signal , wherein the second complementing signal is the same as the first complementing signal; combine the second input signal and the second complementing signal to a second combined signal ; apply a second filter function to the second combined signal for provision of a second left output signal and a second right output signal ; the second filter function comprising one or more head related transfer functions (HRTF_2_L, HRTF_2_R); and output a left output signal and a right output signal via the output interface, wherein the left output signal is based on the first left output signal and the second left output signal , and the right output signal is based on the first right output signal and the second right output signal . a processor ; a source interface comprising a first source interface for a first external source and a second source interface for a second external source; a signal generation module comprising a first noise generator for generating one or more noise signals; and an output interface ; obtain a first input signal via the first source interface ; obtain a first complementing signal based on one or more noise signals from the first noise generator ; combine the first input signal and the first complementing signal to a first combined signal ; apply a first filter function to the first combined signal for provision of a first left output signal and a first right output signal ; the first filter function comprising one or more head related transfer functions (HRTF_1_L, HRTF_1_R); obtain a second input signal via the second source interface ; obtain a second complementing signal , wherein the second complementing signal is the same as the first complementing signal; combine the second input signal and the second complementing signal to a second combined signal ; apply a second filter function to the second combined signal for provision of a second left output signal and a second right output signal ; the second filter function comprising one or more head related transfer functions (HRTF_2_L, HRTF_2_R); and output a left output signal and a right output signal via the output interface, wherein the left output signal is based on the first left output signal and the second left output signal , and the right output signal is based on the first right output signal and the second right output signal . <EOS>