## 6 Conclusions  
The research described in this paper focused on determining whether speech samples can be used for calibrating the reproduction level in non-laboratory listening test setups, e.g., for home online listening tests. In the listening part of the conducted experiment, the subjects were asked to set the volume of the sound reproduction system so that the loudness of a reproduced speech sample would feel \"normal\" to them. The resulting A-weighted level of that speech was collected as the output variable. Groupwise, the only significant difference of 5 dB was found for the change of the sound reproduction system from loudspeakers to headphones, and the subjects were prone to setting a higher reproduction level when using headphones, i.e., 50 dBA on average on loudspeakers vs. 55 dBA on headphones. On the other hand, the (non)-existence of a visual stimulus in the form of an appropriately clothed dummy head acting as the imagined talker did not have a significant influence on the chosen speech level, and neither did the choice of the speaker voice which the subjects listened to. The interaction between these three factors was not found to be meaningful. The examination of the interindividual differences between the subjects revealed that the subjects exhibit an extremely broad range of what they consider to be the \"normal\" speech level. Consequently, they have the dominant influence on the outcome of this experiment, showing that level calibration using a sample of speech is not a viable solution if the calibration is made simply by adjusting the reproduction level so that the loudness of speech would be perceived as \"normal\". In the reading part of the experiment, the subjects were asked to read a paragraph of text in their \"normal\" voice. The results reveal that the subjects were considerably more consistent when reading at a \"normal\" speech level than they were when they needed to set it by listening to a speech sample. Depending on the condition of the visual stimulus, the average reading level ranged from 55 to 58 dBA, and the lowest value was found for the visual stimulus placed within the personal space of the reader. The examination of the interindividual differences reveal that the level at which the subjects read is generally consistent with their self-assessment of the type of talker they are. No influence has been found of the subjects' age, gender, possible hearing impairment, and their habits related to listening of music and speech on their perception of \"normal\" speech level, both while reading and while listening. Based on these findings, a method of level calibration that involves read speech as a reference calibration sound was proposed for possible use in non-laboratory listening setups. The method involves a live reader placed at conversational distance of 1 m from the test subject. The reader reads a paragraph of prepared text at a normal level of 55 dBA. The test subject performs loudness-matching of read speech with a sample of pre-recorded speech, thus calibrating the level of the pre-recorded speech at 55 dBA, and, consequently, the presentation level for the entire listening test. Future research needs to address some aspects of the proposed method that were beyond the scope of this paper: (a) the difference, if any, between reading to a live person rather than to a dummy head, (b) the ability of the subjects to perform subjective loudness matching of two speech samples and the possible influence of the (mis)match of speaker voices and/or speech content, (c) the degree of the \"6-dB mismatch\" between loudspeaker and headphone presentation in conditions specific to the described application, and (d) the response of the potential test subjects to the increased complexity of the proposed method of calibration. Conceptualization, D.K., M.H. and K.J. ; methodology, D.K., M.H. and K.J. ; software, D.K. and P.F. ; validation, M.H. and K.J. ; formal analysis, D.K. and M.H. ; investigation, D.K. ; resources, M.H. ; data curation, D.K. and P.F.