Axiom Home Page Forums General Discussion Technical Questions blind testing of speakers

thanks Alan for your answer; and the same to everyone else too who contributed, including the good laughs. :-)

Wow, that is a very old pic of Alan, Rick.

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So, we can hear differences of less than one db, it just doesn't register as louder.
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You got it, Fred. Small differences in sound level which aren't clearly identifiable as such can instead be described as factors such as "stronger bass", "clearer highs", "fantastic imaging", etc. This is particularly noteworthy in components such as amplifiers and players which have no capability to affect those factors when played at matched volume levels.

fredk

The perceptibility of loudness, and other differences caused by one being louder than the other, is an interesting test. By simply having the only difference in your double blind listen test between position A and B a difference in dB you can judge the effect of this phenomenon in isolation. When you are 2 dB louder you will get comments referring to the difference in SPL along with other comments about the sound difference which will be favourable for the slightly louder one. As you get down to 1 dB the comments in regards to SPL will start disappearing leaving just the odd comment about minute advantages for the slightly louder one. Once you are down to a ½ dB difference the comments about differences of any nature will disappear. If you can keep your test products within a ¼ dB of each other then you know this variable is out of your results.

For setting up the levels we use IEC 268-5 weighted noise. It is rolled off below 40 Hz and above 5 kHz. You do want a good meter for setting this up too. Though the SPL meter only needs to read a difference between the two products and not any sort of absolute SPL, it does need to be linear and broadband. We use our B&K SPL meter as the benchmark.

Ian, thanks for detailing the sound source used for calibrations.

Thanks Ian and John. Ian. In my mind, your posts reconciles some of the difference of opinion between different researchers. I believe it was Toole that suggested that you could hear differences as little as 1/2 db. I think it was something quoted by a third party and no explanation was given as to what difference you might hear.

For all that, my M80s sound great at all db levels up to the 'you gonna break your eardrums' setting on my receiver.

Ian, thanks for taking the time to post this. Interesting stuff!