Room 'deadness' for audio playback.

[pastedavid]

Hello all,

Are there any guidelines for this? I have noticed that I MUCH prefer the so und of my lounge when the two sets of curtains are drawn. There is much les s echo - or not quite echo but perhaps reverberation? (I don't really know much about this sort of stuff) and the TV and stereo sound much better.

I did a quick search of the internet but all I could really find were somew hat technical discussions about the quality of recording rooms.

I got thinking about recording rooms and saw this photo of an Abbey Road st udio:

which seems to be a hollowed-out house (I have never been there, just seen photo's) which has big spaces for recording. So would this room sound dead? If the space is larger, surely sound behaves like light in that the furthe r away from the point source, the weaker the power level, and therefore the weaker any resulting reflections will be.

I really hope someone can imagine what I am trying to describe here!

Thanks in advance,

David Paste.

[tony sayer]

In article , [e-mail] scribeth thus

It'd be tuned so its a little "bright" and with carefully controlled reverb and well insulated against extraneous noises.

Very famous place .. Elgar and the Beatles were known well there:)

Especially the pedestrian crossing outside when that was on the Abbey road album and EVERY Japanese tourist that comes to London wants their pic taken outside;!. It's even got a webcam:!....

[Bert Coules]

What you've discovered is that the wall (and floor and ceiling) surfaces make a big difference: With the window, a large area of glass reflects back the sound, making it brighter, more toppy and lively (hence "a live acoustic"). When the curtains are drawn, the fabric, especially if it hangs in folds, absorbs some of the frequencies, there's less sound to bounce around and the overall quality is deader.

Rugs on a hard floor do much the same thing. A similar, but less pronounced, effect comes if a plain wall surface is broken up and made irregular - by having shelves with occasional items on them, for example, or hanging fabrics. Soft furnishings help, too, and even putting a fabric cloth on a table can make a difference. The ultimate in deadness is achieved in some areas of some recording studios by having all surfaces (sometimes including most of the floor) covered in irregular spikes of absorbent material. Being in an almost completely dead room can be a very disconcerting experience.

Absolute hifi nuts will tell you that what you wear when listening to music affects the sounds too. It does, but I don't know anyone who deliberately chooses what they wear according to the acoustic they're trying to create.

[Bert Coules]

Here's a short news report about the oddness of being in an almost completely sonically-dead space (or anechoic chamber, to give it its scientific name):

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[The Natural Philosopher]

Multiple random reflections are your freand Decorate the walls with egg boxes or tapestry

[Chris J Dixon]

I once spent some time on a project in a simple form of anechoic chamber, and it was indeed quite strange.

As I was doing tests near the hearing threshold, I set up my kit with a sound level meter, which happened to have a scope output. Out of curiosity, I had a look at things with a flat response selected (instead if the usual "A" weighting), and was surprised how much low frequency stuff there was about.

One odd aspect was that, although external airborne noise was well suppressed, they hadn't managed fully to isolate the chamber from the basement floor it stood on. There was a railway line about 1/4 mile away, and although I never ever heard a passing train outside the chamber, inside they were clearly audible.

You don't realise how loud your breathing is until you are in such a quiet environment.

Chris

[Dave Plowman (News)]

The two are very different. For recording say a classical orchestra, you likely need a hall with a reasonably long reverb time which is also contains reflective surfaces. If, say, a violin player can't hear himself being reflected back he tends to play rather harder. For a pop recording where everything is individually miked up you'd ideally use a much 'deader' studio.

As regards the listening room, you ideally don't want that to add acoustic to the recording, so the 'deader' the better. Lack of reflections in a room help considerably with the positioning of things in the sound stage. Of course a very dead room may not be pleasant for general use, so a compromise is usually needed at home.

The fashion for wood floors has done nothing to help this - a decent thick fitted carpet helps enormously.

The shape of the room is quite important too - the more it approaches a cube, the worse it becomes.

[R.G. Bargy]

the two sets of curtains are drawn. There is much less echo - or not quite echo but perhaps reverberation?

Related topic: I am put off visiting several pubs and restaurants locally (Cheshire/South Manchester area) as the interior designer(s) seem to have b*ggered the acoustics by excessive use of hard surfaces on walls, floors, ceilings and furniture in their modernisations. Sounds bounce around unrestrained. Localised conversations become unclear, so everyone speaks up more and more. Some even have an open-fronted kitchen to add the clatter of cooks throwing pans and cooking implements around.

Result: struggle to follow a conversation at the same table and the whole ambience becomes a strain - unbearable to my ears.

Anyone else notice this unwelcome trend?

BTW1: I even had my ears tested because I thought it might be due to my age or some other problem. Nope, and the practitioner confirmed that it is the building interior that is at fault.

BTW2: I prefer the decor (and beer) of less trendy places anyway - which probably is an age thing. :-)

[R.G. Bargy]

the two sets of curtains are drawn. There is much less echo - or not quite echo but perhaps reverberation?

Related topic: I am put off visiting several pubs and restaurants locally (Cheshire/South Manchester area) as the interior designer(s) seem to have b*ggered the acoustics by excessive use of hard surfaces on walls, floors, ceilings and furniture in their modernisations. Sounds bounce around unrestrained. Localised conversations become unclear, so everyone speaks up more and more. Some even have an open-fronted kitchen to add the clatter of cooks throwing pans and cooking implements around.

Result: struggle to follow a conversation at the same table and the whole ambience becomes a strain - unbearable to my ears.

Anyone else notice this unwelcome trend?

BTW1: I even had my ears tested because I thought it might be due to my age or some other problem. Nope, and the practitioner confirmed that it is the building interior that is at fault.

BTW2: I prefer the decor (and beer) of less trendy places anyway - which probably is an age thing. :-)

[Jethro_uk]

They'll also tell you cables linking equipment have a directionality ...

[Brian Gaff]

Well, if you have some form of recorder and set it going in the room then clap or speak or play a stereo, you ill be surprised ou how different it sounds to you than the ears on your head hear it to be when live. Use headphones to listen to the recording or use headphones for a live microphone.

The issue is that people hear things differently, and what souits one person will annoy another. Basically, the less reflective to sound the floor and walls and ceiling are, ie the more absorbtive they are, the deader it sounds. What you need to ask yourself is would that really be what you want? I was fortunate enough some years ago to go into an anechoic chamber where they test things for sound emission etc, and when there is no sound being generated in such a place, it feels very uncomfortable and as if the whole room is closing in around you. Brian

[Brian Gaff]

Chuckle certainly not indeed. However, one effect not mentioned yet is corner resonance.If you play a bassy track and move into a corner, normally the bass is louder there due, presumably to the adding effects at the longer wavelengths of sound. also of cours small rooms tend to need more bass to sound right as there is not enough room to allow the wave to exist. Note the in car model where the bass bin in is needed, and all it does is move the actual material the car is made form to allow the bass to exist. Hence when one goes by you hear the bass and not much else. Acoustics are very complex, and really if you are trying to find a good room design it can be a long process of moving where things are and furnishings about a lot. Brian

[Brian Gaff]

Yes and one particular individual will sell you mains cables costing the best part of 1000 quid as they make it sound better, its balderdash most of the time, though coiling up speaker cables is not a good idea. Brian

[Brian Gaff]

Yes, see my earlier message about the weird effect. Its actually quite disconcerting. I actually felt rather sick. Isolation of structure borne sound is notoriously difficult as after all you have to be connected to the ground somehow. Maybe one should construct ones listening room held aloft by a balloon. I must suggest this idea to Russ andrews.

Brian

[Brian Gaff]

Egg boxes need to be of the papier mache kind, not the plastic kind. However health and safety folk frown on such things as fire hazards.

Brian

[Bill]

In message , The Natural Philosopher writes

Curtains with an air space behind them are better for balanced dispersion/absorbtion of sound.

[John Williamson]

The "room within a room" approach works quite well, as lomg as the inner room is mounted on something compliant enough. You do need deep pockets, though, and bass traps if it's not a huge room.

It's a topic that often comes up on rec.audio.pro

[Dave Plowman (News)]

Quite. I've no idea where the notion that egg boxes are a decent way to treat a wall came from. Because they are near useless. Perhaps it's because some types of acoustic treatment may be shaped vaguely like egg boxes.

[The Natural Philosopher]

no. they do stop hard reflections.

They are better than nothing and cheap. They are nowhere near as good as what they resemble to which you allude, I acknowledge. I saw a few budget 'semi pro' studios equipped with them in the 70s.

Better than bare concrete or masonry.

Tell you waht which may amuse you. Sometimes I need to clap my hands to call in a dog that's gone looking for love. There is a copse 150meters away planted in a straight line. I can clearly hear an echo off it. And from a similar one 300 meters way plus.

At might I can walk through the woods and 'hear' roughly where trees are by the reflected sounds I make..

the 'sound' of being in open country is totally different.

[RobertL]

sound of my lounge when the two sets of curtains are drawn. There is much l ess echo - or not quite echo but perhaps reverberation?

I used to work (in 1973) in the world's largest (at that time) 'dead room'. It was the anechoic chambre at the Building Research Station. It had 4 f oot long polyeurathane foam wedges sticking out of the walls and the ceilin g and the floor. You walked on an open wire mesh 'trampline-type' floor. The door (motorised) also had wedges on it.

It was very big; they had a symphony orchestra in there at one time.

I'd sometimes go and sit in it with the door closed. It was VERY quiet. Y ou could hear the blood going round inside your head. If you listened to someone else speaking you got no sensation of distance. As they walked awa y from you the voice got quieter but otherwise was unchanged.

Next door was the reverberation chambre - a huge room where no two walls we re parallel and everything was done to make the walls hard so the reverbera tion time was very long (20 seconds IIRC).

They would put test panels in a 'window' between the two rooms to measure a coustic properties of building materials.

Just though I'd share that...

Robert