PercentilesA central element in the statistical analyses performed in Widex hearing aids is percentile levels. The figure below illustrates how the level of the sound changes over time. In the beginning it is soft, then it becomes a little louder, then soft again, then very loud, and finally soft again.  Illustration: Changes in the loudness level of the signal over time The level histogram below shows how often each level occurred in the signal over time. The sound level has been measured at regular time intervals, and each loudness level’s frequency of occurrence has been plotted.  Illustration: The x-axis shows the loudness level (the leftmost column shows the softest level). The y-axis indicates how often each level has been measured. One piece of information that would be relevant to extract is precisely how soft the soft parts of the signal are and precisely how loud the loud parts are. This is where percentile levels can be helpful. A given percentile level indicates how much of the signal was below or equal to that particular loudness level. For example, the 10% percentile level is the level at which the signal was louder 90% of the time. Thus, if we identify the 10 most quiet percent of the measured level, we have a good indication of how quiet the quietest part of the signal was.  Illustration: The 10% percentile level indicates how quiet the quietest part of the signal was Similarly, if we want information about how loud the signal becomes, we could extract 90% of the softest measurements. In other words, we could extract the 90% percentile level where the signal is louder only 10% of the time. A high level percentile such as the 90% percentile will provide information about the peak level in the signal.  Illustration: The 90% percentile level indicates how loud the signal was In this way, percentile level estimation can provide statistical information about the ambient sound environment which can be used at different stages in the processing sequence to make sure that the right amount of gain is provided for the specific user in the specific situation. |  Widex around the world Further questions? Contact your local Widex distributor. |