Help setting up multiple filter/eq with parametric settings

I am totally unfamiliar with nyquist prompt but the few parametric.ny files I’ve been able to find online don’t seem to run anymore in Audacity - I’m guessing they’re old and haven’t been kept up to date? I’m trying to implement a house-curve correction filter that is made up of 20 different parametric EQ bands.

Can someone give me a nyquist prompt that I can then put into a chain in audacity to batch filter recordings made in the recording booth?

Here’s a sample of the parameters for the house curve:
freq1=82.7Hz gain1=-8.7dB q1=2.85
freq2=91.7Hz gain2=13.6dB q2=3.18
freq3=152Hz gain3=-7.6dB q3=2.99
etc… for 20 total filter points


I’ve just tested this one in and it works fine:

Maybe I’m misunderstanding how to use the nyquist prompt feature of audacity. My actions are as follows:
-open soundfile
-select effects>nyquist-prompt
-copy the text from the parametric.ny that you linked to
-paste into the nyquist prompt window
-click okay
-read the error “Nyquist did not return audio.”
-click okay and notice no changes to the audio file.

Am I missing something?

Which version of Audacity and which operating system?

That was my initial thought as well, so I updated from 2.0.5 (on OSX) to the latest git version since nyquist prompts in chains aren’t yet in the latest release but are in the git repository. Now all is working.

Am I correct in thinking the easiest method to complete this task is to set up multiple nyquist prompts (one for each filter) in a chain?

It seems the latest git code is a bit buggy with nyquist chain implementation (as well as always crashing anytime I try plotting a spectrum). I have set this up but each time I run the chain absolutely nothing happens to the soundfiles. Any thoughts?

The best way is probably to make a Nyquist plug-in that does what you want, and use that in the Chain.

A bit of history:
The Nyquist Prompt was originally designed as a quick and easy way to run short Nyquist commands.
In Audacity 2.1.1 the Nyquist Prompt has been substantially upgraded so that it can now run full plug-ins. However, the standard and recommended way to run a Nyquist plug-in remains the same, and that is to install the plug. See here for how to install Nyquist plug-ins:

The basic Nyquist command for parametric equalization is:

(eq-band signal hz gain width)

So, for example, if you wish to apply +3 dB gain to a frequency band that has a centre frequency of 1000 Hz and a half-gain width of 0.5 octaves, the command would be (Nyquist version 4 syntax)

(eq-band *track* 1000 3.0 0.5)

where “track” is the selected audio in the track that is being processed,

To make that command into a plug-in, you would add the appropriate headers (see:, save the text as a file with a file extension of “.ny”, and then install the plug-in.

Multiple “eq-band” commands can be applied simultaneously by nesting the commands, For example, to apply +3 dB at 1000 Hz, and -4 dB at 2000 Hz, each with a half gain band width of 0.5 octaves:

   (eq-band *track* 1000 3.0 0.5)
   2000 -4 0.5)

To write the code for applying gain to many frequency bands it would be better to create a loop rather than writing out lots of filters in long hand.

However - getting back to the purpose of your enquiry, why not just create a custom curve in the Equalization effect? (see:

Yes I know. Annoying isn’t it :frowning:
Hopefully someone will be able to fix this before the next Audacity release.

I’ll try re-working the nyquist script that way. Hopefully that will correct the behaviour I’m experiencing.

Creating a custom curve in the Equalization effect wouldn’t be nearly as precise as specifying the gain, q, and centre frequency of each band I want adjusted. The room was measured with RoomEQWizard and it spits out a correction filter that I’ll need applied. I even looked into manually editing an eq curve xml file for the equalizer hoping that internally it stores it as individual filters with q and gain, but alas it’s just a graphical EQ and won’t do for this purpose.

It seems that this issue only affects some users (myself included).
What operating system are you using?
How often does this happen?
Anything else that you can tell us about this that may help to pinpoint the bug?

Operating system in question is OSX 10.9.5 and I was using the latest Git version as of a last week. Crashing upon attempting to plot spectrum is as regular as a swiss watch. Crashes are so brutal that the bug reporting mechanism hangs on the beach-ball-rainbow of death until the program is force-quit. I’ll try the latest git on a few other OS’es I have running to see how widespread it is.