Room treatment using plants.
Posted by: CharlieP on 10 November 2015
I posted this on HH's "socks" thread, but thought it worthy of a tangent discussion. I am curious to know if others have tried this.
Spurred by one of Huge's room treatment threads, and a discussion with joerand, I got to thinking about acoustic room treatment to address an issue with the sound of my system. In this thread I am not talking about bass issues or room modes, but higher frequencies where midrange and treble reflections can compete with first arrival sound. My speakers sit out in the room, 63 inches (1.6m) from the back wall and 54 inches (0.61m) from the fireplace. The first reflection off the fireplace is delayed about 7 to 8 m-sec. (close to Haas effect limit). I felt I needed to absorb or diffuse the first reflection from the speakers off the brick fireplace behind.
As a quick experiment, I grabbed three bed pillows and hung them from the mantel. This did not look so good, but my wonderful wife tolerated them temporarily as an experiment. The improvement in sound was not profound, but it was significant enough that i did not want to remove the pillows. They remained for a few weeks, and were in place when I hosted a local forum gathering. Finally, I had to replace them with something more aesthetically pleasing, but what?
I placed tall plants between each speaker and the fireplace, so as to diffuse the sound which would otherwise reflect towards the listener, as you can see in the photo:
To my delight, the plants were even more effective than the pillows. These were quickly relocated from elsewhere in the room, so I plan to replace the one on the right with another palm to approach symmetry. But I consider this to be a very affordable "acoustic room treatment" which noticeably improves the sound field. I hear notes decay into the recorded venue more clearly, as if some muddling "noise" were removed. I recommend this approach as an affordable and domestically acceptable approach to room treatment for taming mid-to-treble reflections.
Charlie
Posted on: 10 November 2015 by CharlieP
Jan, very interesting. Now if we could just get YouTube to display on that panel while the music plays. Or maybe display photo of plants...
I will have to look into Daisy Reflector. I don't see one in our room, but I would like to know more about it. I do respect your recommendation.
Charlie
Posted on: 10 November 2015 by joerand
Charlie,
Great topic and lively responses. My room would benefit aesthetically from the addition of some greenery. A little diffusion would be a sonic boon as well. The challenge for me will be whether my room gets enough light during winter to sustain the plants. I guess now is the time of season to make that determination. Thanks for the inspiration!
Posted on: 10 November 2015 by CharlieP
Originally Posted by joerand:
Charlie,
Great topic and lively responses. My room would benefit aesthetically from the addition of some greenery. A little diffusion would be a sonic boon as well. The challenge for me will be whether my room gets enough light during winter to sustain the plants. I guess now is the time of season to make that determination. Thanks for the inspiration!
Cheers!
Posted on: 11 November 2015 by Tabby cat
Originally Posted by tonym:
I find a few cannabis sativa plants certainly make music more enjoyable to listen to.
Brought a big smile to my face Tony......well funny.
Posted on: 11 November 2015 by Tabby cat
Originally Posted by Tony2011:
Originally Posted by Hungryhalibut:
Christmas trees? Really? That's a great idea! Someone was selling glass jars of pebbles a while ago, at ridiculous prices, which if suitably placed, would transform your listening experiences. Allegedly.
That plants have an impact must be undeniable, just think how they are planted near noisy roads, and how it sounds when one is in the woods. I think it's a lovely idea, and so much nicer than horrid acoustic panels.
With my wall hugging speakers plants are not an option, other than ivy I suppose.
A time to be merry!
Missed it first time Tony thought it was a Christmas tree.Wicked mate !
Posted on: 11 November 2015 by Huge
Originally Posted by Jan-Erik Nordoen:
...
No snake oil in this one, just sound use of acoustic principles to deal with an often ignored source of reflections.
Jan
Jan,
Very interesting.
I'm not sure his explanation of how it works is quite right; and if it is right, it certainly misses out a lot of very important details. However even given that, when looking at the wave propagation* from the speakers, it's an ingenious solution, and will be beneficial. As you say, no snake oil!
* N.B. no direct association with the propagation techniques needed for the plant based diffusers!
Posted on: 11 November 2015 by Huge
Charlie, interesting thread.
I hadn't thought of using plants as diffusers, but yes, the right type of plants approximate fractals, and hence are very good broadband diffusers. Brilliant idea.
Posted on: 11 November 2015 by bicela
Indeed, in urban area, trees are used as acoustic treatment on large scale too.
But as far as I know there is no literature on in-house treatment, that's pity.
Posted on: 11 November 2015 by Simon-in-Suffolk
Buts its funny in a wood with tall trees when you move into a clearing you will often get a reverberating sound - perhaps more to do with the wood trunks than the foliage - and wind rustling foliage is a great random noise generator which can help diffuse and mask.
Simon
Posted on: 11 November 2015 by Huge
Simon, precisely that.
The trunks are acoustically reflective and have non-random spacing (even in natural woodland the plants themselves dictate an optimal spacing). It's the foliage that acts as an efficient diffuser; it also gives considerable absorption due to the very large number of reflections occurring (and the reflections are never 100% efficient).
Posted on: 11 November 2015 by DHT
Plants may help with diffusion of higher frequencies, but bass will be completely unaffected.
H
Posted on: 11 November 2015 by Huge
Originally Posted by DHT:
Plants may help with diffusion of higher frequencies, but bass will be completely unaffected.
H
Lower limit of effective diffusion will be (approximately)
f = 344 / d
Where f is the lower limit frequency
d is the diameter of the plant in metres
Below this frequency the diffusion effect will fall off, and below half this it will fall off very rapidly.
Posted on: 11 November 2015 by likesmusic
CharlieP - I'm not sure you're right about the reason for the plants effect. You say you have placed them at the first reflection points. True, but this reflection point will only "see" lower frequencies because the baffles on your speakers are say 500mm, so the upper mid and high frequencies can not get round this backwards. As others have said, the plants will be completely ineffective for lower frequencies as their wavelengths are much larger than the size of the branches or leaves. The high frequencies that the plants may be dispersing will be getting there mostly likely as reflections from the wall behind your head. So, why not try putting some absorption or diffusion on the wall behind your head? Time to get the pillows back .. or the sofa cushions stacked up on the back of the sofa maybe .. And putting some diffusion at the first reflection point on the side walls is also considered to be a good idea - midrange and treble will hit these.
Posted on: 11 November 2015 by J.N.
Here's mine; taking the first-reflection 'sting' off a plastered wall adjacent to the l/h speaker.
Come on Naim - 'Super-Flora' Room Tuned Plants. A marvellous marketing opportunity.
John.
Posted on: 11 November 2015 by hungryhalibut
Wow, what an improvement.
Posted on: 11 November 2015 by sjbabbey
Enough to give you the colly wobbles?
Posted on: 11 November 2015 by Huge
HH, have your feet fallen off?
Posted on: 11 November 2015 by hungryhalibut
Feet or veg, it's one or the other.
Posted on: 11 November 2015 by Huge
Just so long as you don't get confused which is which; dicing and boiling your feet would be rather undesirable in all aspects.
Posted on: 11 November 2015 by TOBYJUG
Originally Posted by Hungryhalibut:
Wow, what an improvement.
HH Some room for some Aspidristras in front of the hearth me thinks.
Posted on: 11 November 2015 by CharlieP
Originally Posted by likesmusic:
CharlieP - I'm not sure you're right about the reason for the plants effect. You say you have placed them at the first reflection points. True, but this reflection point will only "see" lower frequencies because the baffles on your speakers are say 500mm, so the upper mid and high frequencies can not get round this backwards. As others have said, the plants will be completely ineffective for lower frequencies as their wavelengths are much larger than the size of the branches or leaves. The high frequencies that the plants may be dispersing will be getting there mostly likely as reflections from the wall behind your head. So, why not try putting some absorption or diffusion on the wall behind your head? Time to get the pillows back .. or the sofa cushions stacked up on the back of the sofa maybe .. And putting some diffusion at the first reflection point on the side walls is also considered to be a good idea - midrange and treble will hit these.
likesmusc In my case this works a wonder, because my speakers have a rear tweeter and are nearly omnidirectional. With typical speakers, however there is plenty of midrange making its way around the edge of the box. The other obvious locations for plants would be the side wall and back wall. Charlie
Posted on: 11 November 2015 by CharlieP
Here's what is behind my head.
Posted on: 11 November 2015 by CharlieP
Originally Posted by Hungryhalibut:
Wow, what an improvement.
HH, that looks very nice. Add a few more.
Posted on: 11 November 2015 by likesmusic
Originally Posted by CharlieP:
likesmusc In my case this works a wonder, because my speakers have a rear tweeter and are nearly omnidirectional. With typical speakers, however there is plenty of midrange making its way around the edge of the box. The other obvious locations for plants would be the side wall and back wall. Charlie
Fair enough CharlieP, I didn't know about the backwards facing tweeter!
Posted on: 12 November 2015 by Naim Gary
Charlie, as always I love your takes on things and your "old engineering chops" brought to bear on this thing we love so much - home reproduction of music. It is amazing to see that you have already changed some things in your listening room just since we had our Seattle Naim Forum meet up.
Along with doing some system upgrades I am now looking at redoing our small living room and all these thoughts and ideas are really helpful as I start to think about how to improve my room both acoustically as well as aesthetically.
Keep the good experimentation and reporting of results coming.
Gary
