Psychoacoustics

Dick Rees

Dick Rees

Curmudgeonly Scandihoovian
Jan 11, 2011
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St Paul, MN
When listening to live music in a fairly intimate setting (no arenas, etc), how important is it to you that the original sound arrive before the sound from the speakers?

I do not fully enjoy a performance when I have to listen to the system rather than the music. If the speakers are not delayed back to or behind the performer the "disconnect" between the visual and the audio kind of makes me uncomfortable. I suppose I'd define it as the difference between reinforcement and amplification.

Sometimes it seems as simple as setting the proper delay.
 
Re: Psychoacoustics

Is what you're asking for achievable ?

If there is a noticable delay between the two sounds it's well, noticeable and probably like a slapback sound. Not ideal.

You'll need to get your speakers delayed to within HAAS specifications. This means that one source cannot be more than 10db more than the other so, it may mean that the speaker system must be close in volume to that of the original acoustic source. Is that enough volume for the venue ? Maybe if it's intimate.

But then seating positions will vary distance to the speakers and original acoustic source -part two of HAAS, timing must be under 40ms or so. So getting it right in one spot doesn't mean it's right in another. Then again, intimate venue, maybe.

My .02

Andrew
 
Re: Psychoacoustics

Dick Rees said:
When listening to live music in a fairly intimate setting (no arenas, etc), how important is it to you that the original sound arrive before the sound from the speakers?

I do not fully enjoy a performance when I have to listen to the system rather than the music. If the speakers are not delayed back to or behind the performer the "disconnect" between the visual and the audio kind of makes me uncomfortable. I suppose I'd define it as the difference between reinforcement and amplification.

Sometimes it seems as simple as setting the proper delay.
Click to expand...

+1

Used to do this all the time and I felt it made a big difference in the suspension of disbelief, if there is such a thing in audio. It' cant be done every time in every venue, and perhaps not every seat hears the stage before they hear the speakers. But when it works, it is a nice effect.
 
Re: Psychoacoustics

Karl Winkler said:
+1

Used to do this all the time and I felt it made a big difference in the suspension of disbelief, if there is such a thing in audio. It' cant be done every time in every venue, and perhaps not every seat hears the stage before they hear the speakers. But when it works, it is a nice effect.
Click to expand...

Thank you, Karl. I would only add that I consider it an "effect" when the amplified wave precedes the initial wave. With proper delay there is no effect whatsoever.

DR
 
Re: Psychoacoustics

I agree that alignment is critical, but just as with system alignments, it is always a compromise. Since the stage is almost never set up such that all performers and acoustical sources are in one flat plane, there will always be a disparity in arrival times between downstage and upstage sources. On top of that, the arrival times of the mains and the stage wash will vary significantly throughout the audience.

So, as good as it may be able to be at one point, it will never be (even close) to perfect everywhere.
 
Re: Psychoacoustics

Dick Rees said:
Thank you, Karl. I would only add that I consider it an "effect" when the amplified wave precedes the initial wave. With proper delay there is no effect whatsoever.

DR
Click to expand...

I agree, but I meant "effect" in a different way, i.e. the "effect that it seemed not to come from the speakers". Hopefully that made sense.

And Silas,

True - it's never perfect. At the same time, there is some room for slop. Whichever source arrives first is the one that appears to the listener as "the original". It only has to be 2 or more milliseconds ahead of other copies. But for two sources to appear distinct in time to the listener, they must be 10 ms or more, usually 20 ms later, depending on how much transient information is in the sound. So you have the slop of between say 2 ms and 10 or 15 ms reasonably before you have problems. Thus, you can set up your system so that 80% of the audience is within that zone, and you're probably good. The other 20% may hear things as either "speakers first" or as distinct copies, depending on where they are. If the latter group is say 5%, well, I still think you're better off than if 100% of the audience hears the speakers first and doesn't localize the "original source" as coming from the stage.

This may be a subtle thing, but as I mentioned before, I came to like it a lot and felt that it added something to (or, took something away from) the illusion of acoustic music - I was working with a big band.
 
Re: Psychoacoustics

+1 Yes, the nice thing is that it doesn't have to be perfect. Within a decent range of delays it will pretty much sound similar. We may not get every audience seat into the sweet delay range, but with some effort we can get many of them.

I recall when even a short delay was thousands of dollars (very early Lexicon)... technology now makes this more accessible to more applications.

JR
 
Re: Psychoacoustics

Karl, et al....


As usual the views are dependent on the type of work common to the commentator. I deal mostly with acoustic and "non-rock" music, so the original source is kind of critical for me. If I was doing a lot of rock I'd probably be debating the old "delay it to the back line" or "delay it to the kit" thing. Thanks for throwing in the ms measurements for the different arrival times.

DR
 
Re: Psychoacoustics

I always try to do this with smallish choiirs where they aren't quite enogh to carry naturally butIdon't really want the PA to be noticed. I've always struggled with this with a rock band in a club but I think I've been quite sucessful with more accoustic stuff especially choirs for some reason. G
 
Re: Psychoacoustics

I have been thinking about this because I am not sure just how much of the original "original sound" is arriving at a different time from the amplified sound and at a significant volume. I am obviously considering this from the standpoint of a 5 or 6 piece acoustic string band.

It seems like in our smallest venues where the front of the audience can clearly hear the unamplified sound, the delay is really not as important because in these small venues the FOH speakers are basically in line with the players. At this point I think the thing that is missing in many setups is making sure the front center of the audience is adequately covered with the FOH speakers. I find in many setups that I walk up to that these money seats are actually out of or on the edges of the coverage. Since I don't usually use wedges, sometimes the best view has some of the worst sound (and wouldn't you know that is where the guy with the video camera always goes, if they don't try recording from side stage, behind the FOH:x~:-x~:mad:). I may try a few feet worth of delay in this case, just to see if it makes a difference.

Our largest shows, while not arenas, are big enough that the front row is probably 10 feet from the band and being covered by front fills. In this case I am really not sure the aucoustic sound from stage is meaningful at all, and I would not expect much noticable difference from the delay.

The case where it may help are some of the small theaters (approx 150-300 seats) where there is a significant distance between the stage and the installed system, usually installed as part of the arch. This is where I tend to notice that the sound is a bit more disconnected from the players. This type of high and wide install should also have a smaller range of distances in different listening positions. I know that many people believe it is harder to localize the sound source by height, but without center fills, I find the first couple of rows of seats seem to localize more to the speakers than to the players positions on stage. A couple of feet would probably help here as well. Unfortunately, several of these community theaters i have been in this spring seem to lack any type of dsp control (One was literally from the board to the amps to the speakers, and another one had a analog graphic with a piece of paper over it saying "please do not touch").
 
Re: Psychoacoustics

A few years ago we had a Nexo Geo8 rig on demo. Conveniently coincided with a university fine arts series presentation of Ladysmith Blak Mambazo. We flew the rig from lifts, pretty much right behind the fire curtain line. The group was upstage about 5'. Their engineer asked me to add 3ms of delay, then increment a few 0.10ms until he was happy. Up in the top seats it didn't matter as much, but in the first 1/4 of the hall it had a solid stage image that didn't sound like PA. It was a proper alignment of the PA with the acoustic source for most of the seats where you got appreciable coverage from the singers on stage. He put spike marks on the floor and stand base...

In other circumstances and venues this might have not been an issue, but that day in that room it was the right thing for the audience. Frankly I thought it was stunning; it had an intimacy as if the group was singing just a few feet from you and directly to you, a very personal experience. What a great day at work. :D

Have fun, good luck.

Tim Mc
 
Re: Psychoacoustics

Late September I am off of the summer festival circuit and back to the PAC's. I think I will start playing with this a little, as I almost always have my Sabine navigator with me. It is easy enough to try during soundcheck, and then hit bypass if i am not comfortable with the results.
 
Re: Psychoacoustics

I will stick with 6o6 and treat the original sound just like I would treat a main PA.

So equal level (original vs. amplified sound in this case) -> try to make arrival time equal.

I witnessed this effect to the extreme when I did a freejazz show, where extremely low levels of amplification were needed. So I had only a few channels even on on the desk. I ended the concert with all channels down/muted. It was the best sound job I ever did, can't do better than that. During the transition (band was not leveled on stage at this time, so I had to have a few channels on), delay was vital in order to not mess up the picture completely.
 
Re: Psychoacoustics

Tim McCulloch said:
A few years ago we had a Nexo Geo8 rig on demo. Conveniently coincided with a university fine arts series presentation of Ladysmith Blak Mambazo. We flew the rig from lifts, pretty much right behind the fire curtain line. The group was upstage about 5'. Their engineer asked me to add 3ms of delay, then increment a few 0.10ms until he was happy. Up in the top seats it didn't matter as much, but in the first 1/4 of the hall it had a solid stage image that didn't sound like PA. It was a proper alignment of the PA with the acoustic source for most of the seats where you got appreciable coverage from the singers on stage. He put spike marks on the floor and stand base...

In other circumstances and venues this might have not been an issue, but that day in that room it was the right thing for the audience. Frankly I thought it was stunning; it had an intimacy as if the group was singing just a few feet from you and directly to you, a very personal experience. What a great day at work. :D

Have fun, good luck.

Tim Mc
Click to expand...

This (although a much larger venue/system than I typically have) is what I'm talking about. Properly done the PA disappears as JR so aptly noted.

The point is to have the listener associate the sound psycoacoustically with the source, not the speakers. I just don't like listening to the PA no matter how expensive and sophisticated it may be if there is a chance to feel that you are listening directly to the artist(s).

DR
 
Re: Psychoacoustics

andrew gissing said:
Is what you're asking for achievable ?

If there is a noticable delay between the two sounds it's well, noticeable and probably like a slapback sound. Not ideal.

You'll need to get your speakers delayed to within HAAS specifications. This means that one source cannot be more than 10db more than the other so, it may mean that the speaker system must be close in volume to that of the original acoustic source. Is that enough volume for the venue ? Maybe if it's intimate.

But then seating positions will vary distance to the speakers and original acoustic source -part two of HAAS, timing must be under 40ms or so. So getting it right in one spot doesn't mean it's right in another. Then again, intimate venue, maybe.

My .02

Andrew
Click to expand...

40ms is 35'. IME, IIRC (it's been a while since I've set up delays), 5ms was sloppy alignment on a delay ring that was 40' from the mains. I know we are not talking about delay rings, but the proportions might still apply?
 
Re: Psychoacoustics

andrew gissing said:
Is what you're asking for achievable ?

If there is a noticable delay between the two sounds it's well, noticeable and probably like a slapback sound. Not ideal.

You'll need to get your speakers delayed to within HAAS specifications. This means that one source cannot be more than 10db more than the other so, it may mean that the speaker system must be close in volume to that of the original acoustic source. Is that enough volume for the venue ? Maybe if it's intimate.

But then seating positions will vary distance to the speakers and original acoustic source -part two of HAAS, timing must be under 40ms or so. So getting it right in one spot doesn't mean it's right in another. Then again, intimate venue, maybe.

My .02

Andrew
Click to expand...

On minor point it's "Haas" as in Helmut Haas, the real person who characterized these phenomenon back in the '50s.

JR
 
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