Experiment 6 Rain Density

EXPERIMENT 6
Psychoacoustics

In each group of 5 pairs of audio examples, you will hear a pair of rain recordings with different densities, labelled A and B.

For each pair, the second one (B) will be either higher or lower than the first one in density; that is, the rain will seem to be either heavier or lighter but never stay the same.
Your answer should be: WHICH RAIN EXAMPLE IS HEAVIER?

In the second Group, the pairs should sound approximately equal in loudness,
but your answer is still: WHICH RAIN EXAMPLE IS HEAVIER?

GROUP	DENSITY DIFFERENCE	AUDIO A	AUDIO B	ANSWER
1	1 & 2	Example A	Example B	Answer
	3 & 4	Example A	Example B	Answer
	5 & 6	Example A	Example B	Answer
	7 & 8	Example A	Example B	Answer
	9 & 10	Example A	Example B	Answer
2	1 & 2	Example A	Example B	Answer
	3 & 4	Example A	Example B	Answer
	5 & 6	Example A	Example B	Answer
	7 & 8	Example A	Example B	Answer
	9 & 10	Example A	Example B	Answer

Note: As the density gets larger, you will have noted that the perceptual difference gets smaller and smaller, until it reaches what is normally called the "jnd" - the just noticeable difference.
In previous modules, we've encountered some traditional jnd examples, for instance in pitch or loudness. Few if any comparable examples exist for environmental sounds.
In this case with the rain sounds, as you can hear in examples 9&10, the difference in density is about 10% which seems close to a jnd but still perceptible.

In the group 1 examples, you can detect both density and loudness differences - as would happen in everyday situations - but once the loudness difference is removed in Group 2,
you probably were able to make similar distinctions just based on density, though possibly with greater difficulty.
______________________________________________________________________________________________________________

In these sets of examples, 3 and 4, the rain will gradually increase or decrease in density about half way through the example
but don't worry if the transition isn't entirely smooth - concentrate on the end of the example.
That is, the rain will seem to (A) "get lighter" or (B) "get heavier".

Your Answer is either A or B.

GROUP	DENSITY DIFFERENCE	AUDIO Example	ANSWER
3	5 & 6	Example	Answer
	1 & 2	Example	Answer
	9 & 10	Example	Answer
	1 & 2	Example	Answer
	5 & 6	Example	Answer
	9 & 10	Example	Answer
4	5 & 6	Example	Answer
	1 & 2	Example	Answer
	9 & 10	Example	Answer
	1 & 2	Example	Answer
	5 & 6	Example	Answer
	9 & 10	Example	Answer

How does the experience of a dynamic change in density affect your listening?
In a rainy climate we often get not only a rough idea of "how hard is it raining" but "is it getting lighter or heavier".
That means we're judging the overall stochastic density aurally and are alert to any perceived changes.

In the Group 3 examples, we still have both density and intensity cues, which makes the task easier,
but when the intensity cues are removed in the Group 4 examples, you probably found the differences much harder to discern, even with 5&6, and certainly 9&10.