Assistance system using speech output for providing information to an assisted person, the assistance system comprising at least one sensor for acoustically sensing an environment, in which the assistance system and the assisted person are located, a processor configured to analyze a sensor output from the at least one sensor and to estimate a potential interference of an intended speech output with the sensed acoustic environment in the common environment of the assisted person and the assistance system on the basis of the analysis result, the processor being further configured to obtain information on the assisted person's hearing capacity, to estimate an expected intelligibility of the intended speech output on the basis of the estimated interference and the obtained information on the assisted person's hearing capacity, and to determine a modality of speech presentation on the basis of the estimated intelligibility, wherein the determined modality optimizes the estimated intelligibility for the assisted person and defines parameters of the speech presentation that include a position of an origin of the speech output as perceived by the assisted person and at least one of voice, frequency, timing, intensity, prosody, speech output complexity level, and wherein the system further comprises a speech presentation signal generation unit (4.1, 4.2, 4.3) configured to generate a speech presentation signal in accordance with the determined modality of speech representation and to supply the speech presentation signal at least to a loudspeaker or hearing aid for outputting the intended speech output including the information to be provided to the assisted person. the assistance system comprising at least one sensor for acoustically sensing an environment, in which the assistance system and the assisted person are located, a processor configured to analyze a sensor output from the at least one sensor and to estimate a potential interference of an intended speech output with the sensed acoustic environment in the common environment of the assisted person and the assistance system on the basis of the analysis result, the processor being further configured to obtain information on the assisted person's hearing capacity, to estimate an expected intelligibility of the intended speech output on the basis of the estimated interference and the obtained information on the assisted person's hearing capacity, and to determine a modality of speech presentation on the basis of the estimated intelligibility, wherein the determined modality optimizes the estimated intelligibility for the assisted person and defines parameters of the speech presentation that include a position of an origin of the speech output as perceived by the assisted person and at least one of voice, frequency, timing, intensity, prosody, speech output complexity level, and at least one sensor for acoustically sensing an environment, in which the assistance system and the assisted person are located, a processor configured to analyze a sensor output from the at least one sensor and to estimate a potential interference of an intended speech output with the sensed acoustic environment in the common environment of the assisted person and the assistance system on the basis of the analysis result, the processor being further configured to obtain information on the assisted person's hearing capacity, to estimate an expected intelligibility of the intended speech output on the basis of the estimated interference and the obtained information on the assisted person's hearing capacity, and to determine a modality of speech presentation on the basis of the estimated intelligibility, wherein the determined modality optimizes the estimated intelligibility for the assisted person and defines parameters of the speech presentation that include a position of an origin of the speech output as perceived by the assisted person and at least one of voice, frequency, timing, intensity, prosody, speech output complexity level, and wherein the system further comprises a speech presentation signal generation unit (4.1, 4.2, 4.3) configured to generate a speech presentation signal in accordance with the determined modality of speech representation and to supply the speech presentation signal at least to a loudspeaker or hearing aid for outputting the intended speech output including the information to be provided to the assisted person.