Reverb: Audacity Manual/Code mis-match

It has been a good while since I last visited here, so please accept my apologies if this is in the wrong section or has been covered elsewhere.

I have just downloaded Audacity 2.0.5 and installed it on my Windows 7 system. I was previously using 2.0.2. I wanted to investigate the new Reverb effect. I loaded a WAV file, applied the Church Hall preset for Reverb and then tried to follow the manual which states: “Pressing “Dry Preview” and “Preview” in succession thus gives you a quick “before” and “after” comparison of the effect.” Oh no it doesn’t! :astonished: At least, it didn’t on my system. There was a pop-up window in my way with a “Stop” button on it and I could not switch without stopping the preview. Which is wrong - the manual or the code? :question:

I have achieved what I wanted by applying the effect to a duplicate of the track and using the Solo button to switch between the “before” and “after” versions. :slight_smile:

Also, the install process took me back to the Terms and Conditions from which I had to “Next” to get to the final install window with the “Launch Audacity” and “Finish” on it. I do not understand why I had to revisit that window. :confused: Just a small, mildly annoying bug.


The Manual means that you have to press “Stop” before choosing the other Preview type. I’ll make it clearer since you seem to have an issue with it.

If you prefer short previews and don’t want to press Stop, open the Playback Preferences and reduce the length of the Effect Preview.

Before you start the install process you are shown information about the GPL Licence. After installing you are shown the README. If you had read it you would have seen it is not the same text as the licence but lists the bug fixes and changes in 2.0.5.

The Inno installer is open source so you can compile your own installer if you do not like the one we provide.


Have you increased the default settings for preview length in “Edit > Preferences > Playback”?
Perhaps your expectation of “a quick “before” and “after” comparison of the effect” is less than 6 seconds (the default Preview duration), though I don’t think that a reverb effect can really be assessed in much less than that.
The idea of “Dry Preview” is that you can compare the normal Preview with the original audio without needing to cancel the effect to listen to the original.
Can you suggest some alternative (better) wording for the manual?

OK, I agree that allows you to instantly switch between dry and processed versions, but it is not a “preview” in that if you then decide that you want a larger “room size” setting, you need to Undo, then call up the effect again. The “Dry Preview” allows you to listen to the original audio while the effect is still open.

I rarely use Windows, but don’t most Windows installers show terms and conditions before installing? Would it be reasonable to expect a user to remember what terms and conditions they agreed to the last time that they installed the program (which could have been several years previous)?

My only issue with the phrasing in the manual is that it left me with the impression that I could switch in real-time during the preview. Clarification that this is not the case would, I think, be an improvement. Of course, true real-time switching from Dry Preview to Wet Preview would be even better.

@Steve and @Gale:
Thanks for the quick replies. The excellent service from the elves hasn’t changed while I’ve been away.


One further observation:
In the manual, the green box states “Note that this effect increases the volume,…” I am not finding this to be the case with the four presets that I have tried: Cathedral, Church Hall, Large Room and Medium Room. In all four cases, the volume has been reduced.

I admit, I am on a very steep learning curve here. I am not familiar with the science of sound and acoustics. The material that I am working on is a collection of recordings of our local brass band. The 2009 concert was recorded in the local Methodist Church; the 2011, 2012 and 2013 recordings were done in the village’s Civic Hall. Very different acoustics in the two buildings. The church, as one might expect of a Victorian building, very “echoy”, the Civic Hall, a more modern flat roofed buidling with much lower ceiling and curtains on all the windows, a much “flatter” acoustic. I would like to be able to use items from all these concerts on the same CD and so am trying to bring the sound of the Civic Hall closer to that of the Church.

The workflow that I am currently trying is as follows: Open the original recording, Normalize this -0.5dB, Apply the reverb (Medium Room is giving pleasing results, Large Room was tried but was a little OTT), re-normalize to -0.5dB.

I would welcome any advice from the resident experts.
kindest regards,

Are you sure you have not ticked the “Wet Only” box? For example the Wet and Dry gain reduction for the “Medium Room” preset is only -1 dB. Or is your audio before applying the effect at -0.5 dB but only a few isolated peaks are at -0.5 dB and most of the audio peaks much lower than that?

@ Steve: this is the description of Dry Gain (dB) in the Manual:

Applies volume adjustment to the original (“dry”) audio in the mix. Increasing this value relative to the “Wet Gain” (above) reduces the strength of the reverb. If the Wet Gain and Dry Gain values are the same, then the level of the mix will be made higher or lower by exactly this value (assuming “Wet Only” below is not checked).

“Mix” in the that last sentence seems ambiguous that the output audio after applying the effect might be scaled by this value relative to the level the track had before the effect. For example with the Medium Room Preset (wet and dry gain of -1 dB) my original track at -0.5 dB was increased by 0.5 dB to 0 dB.

Is something like this better:

If the Wet Gain and Dry Gain values are the same, then the mix of wet effect and dry audio to be output to the track will be made louder or softer by exactly this value (assuming “Wet Only” below is not checked).


So far, that is correct.

OK, I can see what that is getting at, but I don’t think it is very clear.

I think that is also correct, but still not very enlightening unless you already know how it works.
I think the point that is being made is that the “Dry” control sets the level before the reverb is applied. In hardware terms the effect is “post fader” rather than “pre-fader”. That is normal (standard) for reverb effects, so personally I’d leave that out from the control description and perhaps mention it as a separate note.

I’ve bookmarked the page and I’ll have a look over the next few days.

Hi Gale,
No, I have not ticked “Wet Only”. The only thing I have done is try the four presets that I mentioned. And that wasn’t done cumulatively either: add reverb, play and listen, undo, add a different reverb, play and listen, undo, etc. The original recordings typically have a peak level in the range -3dB to -6dB, against a general level in the range -9dB to -15dB and with some passages even lower than that. Having chosen my preferred Reverb preset then, as I stated, I normalized these to -0.5dB (I don’t like taking all the headroom and leaving no margin!) before applying Reverb > Medium Room. I have just done another batch but this time I omitted the initial Normalize and went straight to Reverb > Medium Room followed by Normalize. All fifteen tracks dropped volume when the Reverb was added, some more than others.

Let me be absolutely clear what I mean by “dropped volume”. The waveform, whether viewed as “Waveform” or as “Waveform (dB)”, showed a reduced amplitude after applying Reverb, not a massive reduction but certainly a visible and audible one.

Please do realise that I am happy with the outcome of applying the Reverb. My comment about volume was based on the fact that the manual, on the Reverb effect page, stated, without any qualification, that the volume increases. Perhaps all that is needed in that green box on that page is to soften the statement. Something like: “Note that this effect can, in some circumstances, increase the volume,…” would have covered my particular situation.

I have to say that the new Reverb, with its presets, is a huge improvement over Gverb. I never understood that one at all. By trying the presets and noting what has happened to the sliders I am beginning to get a feel for this new effect. Who knows, I might even pluck up the courage to try moving sliders myself eventually!

Hi Steve,
I have tried to clarify the point being made in my immediately previous reply to Gale. What the various sliders do or don’t do is, to me, irrelevant. I am using one of the presets “as is”. The manual page for Reverb said, unambiguously, that the volume would increase - and it didn’t. Therefore I was a) confused and b) worried. All that is needed is a less absolute statement along the lines I have suggested in my reply to Gale.

I am not a professional sound engineer. I don’t want to learn the physics of sound and of acoustics. All I want is something that “does what it says on the can”. On this occasion the can contents didn’t do what was said on the can wrapper. The how, what, why and when of the definitions and uses of those sliders is something that you elves can chew over “ad nauseam”. I am happy to apply Reverb > Medium Room and get a result that meets my needs!


The latest version of the manual (which will be the manual for Audacity 2.0.6) says:

Note that this effect may increase the volume, so the “Dry Gain” should normally be set below 0 dB in order to prevent clipping.

I think that is sufficiently clear.

Yes indeed.

Thanks for your comments. I think we have covered the points raised in the original post so I’ll lock this topic now to avoid drifting off into other issues :wink:

For now I’ve replaced the second sentence with my version (at least it won’t now have a dubious implication) and added your comment in a ToDo. I agree the second sentence doesn’t say much that enlightens but having said what happens when Dry Gain is higher than Wet Gain does invite a question as to what the result of matched gains might be.


I don’t want to extend a locked topic any more, but given that Reverb adds audio, people reading this may be surprised that at zero or small negative gains it might reduce the level of the track relative to its pre-effect level. One explanation seems to be that Reverb acts as a very strong compressor (which I did not know).

For example if I have a short peak at -0.5 dB amidst surrounding audio at -12 dB, running “Medium Room” Reverb, “Wet Only” checked, 0 dB “Wet Gain” reduces the peak to the surrounding level of the output.


Neither am I but the point you raised that Reverb might not always increase the level after applying the effect needed some explanation I feel.