Subjective duration derives from excitation level, not physical duration

Evidence

There are few psychoacoustical data available with regard to subjective duration. Thus, it is not possible to give an extensive model. The results so far, however, allow us to start with a model that is relatively simple, and makes use of the effect of premasking and post masking. In most cases, the effect of premasking may be neglected, while the effect of post masking becomes dominant with short pauses. Using the temporal masking effects as an indication of the excitation level versus time course produced by sound bursts and pauses, the comparison between the time course of sound pressure level and that of excitation level may lead to meaningful interpretations. Figure 12.3 shows, in the upper panel, sound pressure level L as a function of time, and in the lower part excitation level LE as a function of time. Premasking and postmasking, the latter being dependent on the duration of the preceeding masker burst, produce the time course shown in the lower panel. The functions outlined in Fig. 12.2 indicate for a 3.2-kHz tone, that subjective duration of a burst of 30 ms is equal to the subjective duration of a pause of 120 ms. The subjective equality of the two durations can be extracted using the assumption that subjective duration derives from the excitation level versus time course, by searching for those durations that are determined by levels 10 dB above the minima surrounding the time region in question. This means that the subjective duration of the 30-ms tone burst can be assumed as being picked up 10 dB above the excitation level corresponding to threshold in quiet, as indicated by a double arrow. The duration of the pause of 120 ms is picked up 10 dB above the minimum that is produced during the pause in the excitation level versus time course, again indicated by a double arrow. Comparison of the two double arrows indicates that these are almost equal in size. This means that equal subjective duration is produced by such a presentation of burst and pause. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1490

Categorization

• DEFINE: Introduces the model that subjective duration is extracted from the excitation-level time course 10 dB above surrounding minima.