Amateur speaker designer/builder, DSP programmer.

System: my own three-way speakers with linear phase, DSP active crossovers, driver correction, time alignment, calculated in-room EQ to compensate for directivity characteristics. I wrote the DSP software in 'C' using the FFTW library to perform the filtering and convolution; it runs on Linux.

I seem to be the only person around here who is sceptical of all of the following:
  • validity of in-room measurements
  • validity of target frequency responses
  • validity of room correction
  • validity of listening tests
  • validity of statistics in audio experiments
  • validity of (pseudo)science
  • dipole speakers
  • horns
  • bass reflex
  • frequency domain-based thinking
What does that leave? Well, it leaves speakers and systems that are purposely designed to behave very simply (not that the hardware or software is necessarily simple).

Such systems are not contrived kludges based on feedback from over-simplified in-room measurements that assume no ability for human hearing to interpret the audio 'scene', nor from pseudoscientific experiments and the torturing of statistics from inconclusive listening tests; they don't have super-narrow, unnatural, radically modified dispersion; they don't spray antiphase around the room; they don't make assumptions on how human hearing works based on an analogy with a microphone and Fourier transform; they attempt to reproduce the time domain waveform and don't justify phase and timing distortion on the basis of 'legacy' hardware, listening tests and statistics; they implicitly assume that evolution logically gives a human the ability to separate direct from reverberant sound, and therefore logically room correction is not valid.

The common ASR response to all this would be "Prove it..." or, if then pinned down on the true definition of science, "Demonstrate its suggested probability..." or some such. But in doing so, the would-be scientist strays into a minefield of problems that can, to be sure, be waved away with some stated assumptions, but which means that everything that flows from the experiments is based on assumptions that have no scientific basis.

I could create a large list, but let's start with "It is assumed that the knowledge that a person is taking part in an experiment does not alter or hinder their perception of subtle differences...". Not many people would even bother to state this assumption, but it is crucial to any scheme that seeks to justify the design of an audio system using feedback from listening test results. Everything that flows from every listening test is based on that assumption, but without a Truman Show type setup, we can never know whether it is correct or not. Our own inner experience, however, surely suggests that it is not...

So is it safer to use listening tests to base an audio system design on, or is it safer to make logical assumptions such as "The audio system should reproduce the time domain waveform without error, including frequency response, phase and timing"? Or "Human beings can identify the nature and location of acoustic sources in a reverberant environment; therefore they are separating direct from reverberant sound; therefore in-room frequency response measurements do not represent what we hear, and therefore 'room correction' is meaningless".

In audio, it is better to design things based on feedforward logic and justified assumptions, rather than experimental feedback which is, ultimately, based on unjustified assumptions.
Dec 18, 1963 (Age: 55)
Electronics engineer


Digital audio is a rare example of perfect technology; it has given audiophiles everything they wanted. But now they're bored...



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