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Congratulations

You can

hear the difference between the lossy and lossless samples

A p-value is the likelihood that the result obtained would occur by chance if there were no difference. That is, a p<.05 means that if you randomly selected A or B each time, there is a 5% chance that you could get the result you got or one more extreme (i.e. closer to 0% or 100% right).

In psychometric testing a result with p<.05 is often interpreted as the individual detecting the difference between samples.

Because the likelihood of getting one or more extreme results by chance increases when doing multiple tests (i.e. 1 sample = 5% chance, 2 samples = 2 x 5% chance = 10% chance), Bonferroni correction is applied to compensate. Bonferroni correction is done by dividing the cut-off (i.e. p<.05) by the number of samples (e.g. for 2 samples the cutoff becomes 0.05/2, thus the new cutoff is p<0.025)

You got X% correct

Results

You can

hear the difference between the lossy and lossless samples

You got X% correct

Track

Correct

p-value

Can tell

Hungry for more?

You've been invited to do an ABX test

You will be presented with two reference samples (A and B), and a target sample (X). You have to decide whether sample X matches sample A or sample B. You will be administered multiple trials for each of the five tracks used in the original Tidal test.

The accuracy of the test will increase markedly as the number of trials increases. Although 5 trials is sufficient to estimate whether you can tell the difference between the two manipulations, to work out which tracks you can tell the difference on will require 20 trials per sample1.

Note:This test may consume significant data downloading FLAC files. You may not want to do it on your mobile.
These files are not cached due to limitations of javascript FLAC audio libraries.

The reason that you need to do more trials to work out which tracks you can tell the difference on is because of the multiple comparisons problem. The statistical cut-off typically used to decide whether something is 'real' - in this case, your ability to tell the difference between lossy and lossless music - is set so there is a 5% likelihood of thinking there is a difference when there isn't. In this case, that means that for each track there would be a 5% chance of thinking you could hear a difference when you in fact couldn't. When you then test five tracks, the change of that error happening for at least one track is 25% (5% x 5 tracks = 25%). To compensate for this, the metaphorical bar for determining that you can tell the difference for an individual track (in contrast to telling the difference overall) is set very high - five times higher. To reach that bar, you need to do more trials.

In this test, you will be presented with three samples: A, B and X. A and B are consistent, one lossless and one lossy. Each trial, X is randomly set to either A or B. You have to work out which one it is.

Start one of the samples by pressing the relevant button: A to start sample A playing, B to start B, and so on. Once the track is playing, you can switch between the samples by pressing A, B, or X.

Image of the sample selection interface

You can seek through the tracks using the -5s, << (rewind), and +5s buttons, and stop playback using the stop button.

Once you think you know whether sample X is matches sample A or B, enter your choice by pressing X is A or X is B.

Image of the choice interface

Then enter your choice by pressing the Next button.

Image of the next button

Your progress through trials and tracks is shown at the bottom.

Image of the track and trial counters

All buttons also have hotkeys. For QWERTY and DVORAK users, you should orient your hand left hand with your little finger on the A key, and your right hand with your index finger on the 8 key

Action	Hotkeys
Play or switch to sample A	A
Play or switch to sample X	X, S, or O
Play or switch to sample B	B, D, or E
Choose that X is A	Z or ;
Choose that X is B	C or J
Seek back 5 seconds	8
Rewind	9
Seek forward 5 seconds	0
Stop playback	- or [
Enter your response	Enter

blah blah

Flesh & BoneThe Killers

Listen

Choose

Commit

Trial
X of Y
Track
X of Y