11

This question is a companion to Automatically switch equalizer preset based on audio output (internal speaker or external).

Context/problem: bad speakers

As many people know, laptop speakers have "highly unequal frequency response" as audio professional would say. Normal people say: "they sound very bad".

First-step solution: equalization

Equalizing provides a valuable workaround, dramatically improving sound quality with a one-time effort. For example, I installed PulseAudio Equalizer from Web Upd8.

For good results, equalization values should be chosen based on measurements

Measurement time, manual. Done once, not fun.

Once, I took a sonometer app for Android, asked my laptop to produce pure tones, one for each frequency in the pulseaudio-equalizer set of frequencies, and noted down decibels displayed by sonometer app. Then I created a preset with the reversed curve, and I got a pretty decent result.

Measurement time, automatic. Would be fun!

It would be very nice to have the computer:

  • continuously produce some white noise,
  • continuously output that noise to the speakers,
  • continuously measure through a microphone
  • continuously compute a power=f(frequency) spectrum from the microphone signal
  • continuously adjust equalizer parameters to converge to a measured flat spectrum
  • possibly providing some comments like "I can't seem to produce powerful enough bass in the 50-100Hz range (saturation) so I give up" or "too much noise in the 5kHz range".
  • once happy about the result, generate an equalizer parameter file

Then store the resulting profile for pulseaudio-equalizer and profit!

Notice:

  • This assumes that microphone has a flat response, or at least more flat than the speakers being measured, which incidentally I believe is close to true with most microphones even for the cheapest microphones.
  • This assumes that microphone is sensitive enough, or amplified. One may have to tune the audio settings, pick a better microphone or add a preamp.
  • This assumes that microphone hears the same sound as your ears. The simplest option is to have a microphone with a wire and position it where your head is in normal use.

Search before you ask

http://kokkinizita.linuxaudio.org/linuxaudio/ mentions Jaaa and Japa. These optionally produce white noise that may help to do manually what I'm thinking of. When tuning some hardware that only has physical knobs, this is the only option, but here the tuning can be done via API, so I'd like it to be fully automatic.

The question

Is there an open-source software that can, as described above, automatically produce an equalizer profile based on measurements from actual speakers?

  • 1
    Such software seems to exist (I remember setting up my Onkyo receiver that way (they call it "Audyssey Multi EQ"), and Yamaha uses such a system as well, called "YPAO"). Just not sure if it's available to the public and open-source. So fingers crossed! – Izzy Apr 21 '16 at 14:39
  • 1
    The immediate problems asre that it assumes that the laptop microphone is not even worse than the speakers, (many are), and that your hearing response is flat or the same as the microphone. – Steve Barnes Apr 21 '16 at 15:59
1

On Speaker Response Testing and Analysis I found https://sourceforge.net/projects/audmes/ which claims:

AUDio MEasurement System - multi-platfrom system for audio measurement through sound card in the PC. Incorporates Generator, Oscilloscope, FFT, Sweep frequency characteristic. Now it can be compiled and works under MSWindows and Linux.

It's a WxWidget application using RtAudio API.

At first it would not compile. I hacked it to have it compile but it fails to start.

  • I finally had it run. It measures frequency response by sequentially playing a range of frequencies. As a consequence, each full-spectrum measurement is very slow (about a minute) and any noise coming at any time will alter the result of the particular frequency that happened to be tested at that time. So, not of much interest as a starting point. – Stéphane Gourichon Jul 6 '16 at 13:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.