Buying great audio equipment doesn’t guarantee great sound. Your room will make huge changes to the sound of your speakers which prevents you from enjoying your music and movies at their best.
As the room creates the problem, designing and treating it seems logical, but no matter how carefully this is done, you room will dramatically change the sound of your speakers.
Room treatment promises to reduce these problems but it cannot fix the biggest problems that rooms create and can makes sound quality worse, not better.
Few people know much about acoustics which makes them vulnerable to being sold products and solutions they don’t need. If you are buying a home cinema or looking to get the best from your existing system, it’s well worth doing a little research. It could save you a fortune and is the only way to be sure the system you buy provides the best performance at your budget.
I’ve installed over a thousand home cinemas and have built dozens of custom listening rooms. This is my guide to perils and pitfalls of acoustic design and treatment.
Acoustics – Lessons from The Concert Hall
Most people know that some concert venues sound better than others. For 1000’s of years acousticians has been designing spaces to enhance the sound of the musicians and actors on stage and they regard the auditorium and the reverberation it adds as a vital addition to the performance.
The Problem with Home Audio
In the home, the sounds reflected off the walls and other surfaces in the room adds to the direct sound from our speakers. Remove these additions from the room and sound quality will suffer.
One big difference between home audio and concert venues is the size of the spaces involved. The small rooms we use for hifi and home cinema ruin the bass from our speakers because these sounds have long wavelengths that will between the walls in the room.
Imagine your room was full of water with waves moving back and forth. At some points in the room, the waves will be really high, while at others there will be big dips.
This is what your room does to the bass frequencies, amplifying some sounds while others are cancelled making the overall sound far from accurate.
Love Thy Speakers
Good speakers will have a smooth even frequency response that looks something like this.
The smooth graph illustrates they will reproduce every frequency as loud as the next. This measurement was taken 1m away from the speaker but we typically sit 3-4m away from the speakers in a home cinema. At this distance, more than 80% of the sound you hear will have bounced off the walls and other surfaces in your room.
These graphs show the same speaker measured in 6 different rooms. You can see the smooth, even response of our speaker has gone and the same speaker will sound very different from room to room.
Room treatment uses panels and other materials placed around the room to try and restore the smooth response your speakers were designed to give. High frequencies can be easily reduced with room treatment but at low frequencies it has almost no effect.
Reducing a wavelength that is say 10cm long needs material half this depth, but as some bass waves are over 10m long, adding the 5m of material 5m needed to absorb them is simply not feasible.
Human hearing deals with 20,000 different wavelengths. Accurately adjusting all of these to restore the even response of your speakers with a few different types of materials just isn’t possible.
As treatment can’t preserve the sound of your speakers, it focuses on a much simpler issue, reducing the reverberation time in the room. The reverberation time of a room is just a measure of how long it takes sounds to die away and become inaudible.
Clap your hands in a room with carpets, curtains and soft furnishings and you’ll hear no echo because the “softs” in the room have absorbed those echoes. Do the same thing in a kitchen or bathroom and you may hear a slight echo because there is nothing soft to absorb the sound.
Most UK listening rooms are carpeted, if not adding a rug in front of the speakers has a similar effect. This gives most UK homes a perfectly good reverberation and makes them for enjoying music and film. If things are too live, just adding a curtain is a very effective way of reducing reverb time.
While reverberation time is an important measure of sound in large commercial spaces, it’s rarely a problem in UK homes and is of limited value as a guide for good audio in the home audio.
Do No Harm
It’s critical that the sound coming directly from your speakers is smooth and even, but it’s also vital that the reflections from walls, etc are also smooth and even. The sound you hear in a room is a combination of direct sound from the speakers and reflections from the room and unless both sound the same, overall sound quality will be compromised.
Whenever treatment is placed on a wall, it will perfectly absorb some frequencies, while reducing others. This changes the sound of the reflections from your room so the overall sound of your speakers is compromised.
Most “acoustic designs” do no real analysis of the room and simply recommend adding a few different types of materials to the walls. These will change the overall sound you hear from your speakers, compromising their performance.
Room Correction – A Solution for Better Sound
Every room will make speakers sound different. The only way to know the effect the room has had is to measure the performance of the speakers in the room. Without this information, achieving accurate sound is impossible.
Electronic room correction systems measure the sound of your speakers in your room and try to correct the peaks and troughs the room has created. These systems vary considerably in quality, but the process of measuring the room and electronically correcting the problems is the only method that has the potential to deliver the best sound quality.
Testing the Theory
There is a huge amount of misinformation talked about audio and selling room design and treatment very lucrative. If you are considering a home theatre or music room please do your own research and trust your ears to guide you.
My business has focused on delivering the very best audio possible for over 30 years. In recent years I’ve heard many great speaker systems that have been ruined by expensive room treatment.
This photo shows a purpose-built listening room we had designed by one of the world’s leading acoustic design firms. It was built to the perfect proportions with extensive bass traps, diffusion panels, adjustable ceiling diffusers and absorption. It’s a far more intelligent design that most systems that simply recommend fixing fabric panels to all the walls.
Once completed, I was totally underwhelmed by the sound of the room. I was regularly installing the same speaker system used in this room, in client’s homes and achieving much better sound without any treatment.
The performance of the system in this room is now exceptional with incredibly even response down to 10Hz. This sound quality has only been achieved by the use of the best bass management and room correction available from Lyngdorf Audio. The state of the art in room design and treatment did not deliver great audio.
This is an illustration of our second cinema where there is no acoustic treatment. The Steinway Lyngdorf system we use here is intended for use in rooms without room treatment. You can immediately hear it is superior to the system in the purpose-built listening room.
We have 5 listening rooms, only one of which has any acoustic treatment. We keep 10 different systems for you to audition, each of which provides accurate frequency response, exceptional bass due to the room correction system used.
There is no acoustic treatment or design process that can deliver these results
Your listening room is not the enemy whose effects should be eradicated. It should be a positive addition to your audio system. If you are considering a home cinema or great audio system, be sure to find a designer who understands this.
If you would like to audition these system and put the theory to the test, please get in touch.
When the Virus has passed I look forward to having Forum Open Days once again.