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Originally Posted by intlplby
what is your methodology for the study going to be?
what exactly is the variable you are measuring? how are you measuring it?
will they compare different level bitrates to each other or to a lossless source?
are you going to use music? or are you going to use test sounds?
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i dont know all the details of the study yet, im just considering it all and i was bored at work so i thought id start on the fun part, looking at equipemt =]
my thought was to have them compare the same song [as in music] at different bitrates and JUST order them in increasing quality as they perceived it without a lossless version to compare to.
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Originally Posted by intlplby
be aware that a subjects lack of familiarity with a certain genre of music will make them less able to pick out certain details..
i.e. use classical music with a population, such as older adults, where most people are familiar with and listen to classical music regularly will most likely result in higher selected bitrate.... i.e. they may percieve no difference between 256 and 320
in contrast to:
use classical music with a population, such as college students, where most people are unfamiliar with or don't listen to classical music much if at all will most likely result in a lower selected bitrate..... i.e. they may percieve no difference between 128 and 192.......
you will most likely have to have 2 factors:
bitrate - continuous - 5 levels
music type - nominal - N levels (where N is number of different songs , all of which are in different genres of music)
e.g. 5 levels - Jazz, Rock, Punk, Classical, Opera....
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yup. ive thought about that and im not sure what im going to do. im thinking of having them repeat the experiment for multiple generes. using one genre for each age group isnt an experimentally sound imo.
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make sure you choose high quality recordings.... studio copies... remastered if available....
it may even be good to include a worksheet where the subject rates their familiarity with each genre on a lykert scale (5 or 7 point)..... or a scale where they put the 5 genres in order with 1 being the genre they are most familiar with and 5 being the genre they are least familiar with
another option may be to have them listen to sweeps or pulses are various volumes..... perhaps combine the sweeps or pulses with pink noise and ask them when they can hear the pulse or sweep
you could start a sweep or pulses and give them a hand buzzer and everytime they hear the sweep start they press the button and you record response time from the start of the sound file to when they first heard the sweep or pulses....... pulses would work better because you would have more defined levels and if you left enough space between the pulses you could compensate for different lag times between subjects |
i really just want to see whether the average joe can really tell the difference between different bitrates, and what is the bitrate where they really cant tell a difference anymore. now that i write this, i think it might be logical to include a lossless version of the song in the experiment just to see if people rank it lower than some lossy version.
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are you using DOE (design of experiments)?
if so what kind of design are you using or what model are you using? taguchi array, response surface design or something else?
is the bitrate going to be the only factor?
what statistical software package are you using? SPSS or JMP?
how many subjects do you expect to get?
what is the power you are trying to achieve? 1% or 5% or some other power?
that is everything i can think of right now |
HAHA! im no stats major. in fact, im a sophmore cs major so you're over my head in this area. bitrate [idealy] is going to be the only factor. as far as software im not sure, may be SPSS but only because thats all ive ever heard of. i plan on finding a stats professor to mentor me through this so hopefully he/she can help me out in that area...and all this other stuff! i definately have over 100 subjects, may be over 200. freshman pysch majors are required to participate in at least 4 experiments so ill be getting a lot of them =]
to answer a bunch of other questions:
im on a budget not because thats all the money i have but because i can only get up to 1000 dollars in funding from a grant. borrowing equipment isnt really an option. if i REALLY need the money there are ways i can get more funding [up to 2000] but i really think i can do this in under 1000.
as far as sources, i just wanted to hunt down some well recorded cd's. its not the best but its not expensive, and they're readily available.
as for the environment, ill definately have a room just for the experiment. CMU has lots of small, solid, almost sound proof rooms so i dont think that will be a problem. I do realize sound isolation is a big deal though.