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Services

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Room acoustic consulting

Ljudbjörnen, also known as Nisse Björn offers room acoustic
consulting either on location or through video meetings. In contrast to what Nisse himself earlier believed to be true, one can actually save money and frustration by letting a competent individual guide clients towards making good och long term judgement calls and avoid costly design mistakes.

800 kr / hour (incl. VAT)

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Acoustic measurements

Acoustic measurements can be very useful and reveal a comprehensive insight into the acoustic tendencies of a room. With a pair of trained and experienced ears, one measurement microphone, one acoustic analyzing software, Ljudbjörnen can help you to properly measure the room(s) of interest.

800 kr / hour (incl. VAT)

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Handmade acoustic products

Ljudbjörnen designs sound absorption panels by hand in Årsta, Stockholm. These broadband panels can be delivered and installed around Stockholm, Sweden.
Click on "Products" in the main menu to get more information.

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Custom builds and installation

Ljudbjörnen offers installation of room acoustic panels as well as custom builds, primarily around Stockholm, Sweden.

700 kr / hour (incl. VAT)

 

Recent projects

Elias Landberg production studio - Stockholm, Sweden May 2022

Elias Landberg a.k.a Skudge is a talented techno producer with a newly renovated studio space. He needed to get the room acoustics under control so that his productions would translate well to other systems. It was a true joy to help Elias with the studio.

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PERC. studios - Stockholm, Sweden April 2022

PERC. studios in central Stockholm hired Ljudbjörnen to consult the owners/drummers Axel Fagerberg and Mårten Hillbom how to improve the room acoustics of their main room. Great vibes and happy customers!

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SearchIntent office - Stockholm, Sweden
Nov 2021

This digital marketing and SEO company in central Stockholm got their acoustic issues greatly reduced. Their meeting room and their video conference room is now acoustically pleasant rooms. The adjustments was documented in the video "Meeting Room Acoustics" that can be seen soon on our YouTube channel Ljudbjornen Acoustics.

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Room acoustics

Room acoustics can be described as how sound propagates within a space

 

Room acoustic criterias are dependent on the intended use of the room. This means that the room acoustic design will vary between different types of spaces with their various functions and needs.


Restaurants:
In a bar or restaurant, adequate room acoustics is needed in order to enable a pleasant experience for the guests and a healthy working environment for the staff. The guests and personal will absorb sound by their cloths and bodies but they will also generate sounds such as: speech, chairs moving, cutlery on plats and so on. Espresso machine in the bar and often music playing. 
To reduce the energy of these sounds and the reflections from windows, ceilings and walls within the room, an installation of a couple of absorption panels would help a lot. 

On top of these sounds, most restaurant environments also have audible sounds arriving from other nearby environments. For example: vehicles passing by outside or duct noise and HVAC systems. To reduce those isolation problems, other would types of adjustments is required.

Criterias for restaurants:

* Good Speech Intelligibility
* Low ambient noise 
* A good distribution of absorptive surfaces throughout the space



Audio production rooms:
In audio production rooms or similar the following needs are some of the most important ones:

* Monitor and listening placement optimization
* Speaker platforms and de-coupling management
* Early reflection control
* Low and relatively even decay times
* Managed modal activity and a controlled low frequency region
* Even tonal balance and frequency response at the sweet spot
* Minimal phase and distortion issues
* Stable stereo image and a good phantom mono image
* Low ambient noise floor
* Possibly sound isolation
* Possibly diffused later reflections so that they actually contributes constructively together with the direct sound path.

When implementing these steps, the room acoustic conditions would enable the producer/engineer to easily distinguish the important details in the audio material by having managed and reduced room character influences.

Audio production rooms usually have way higher requirements for low frequency control than most other spaces. Especially if the room is used for bass heavy music or sound design for movies. In contrast, a podcast studio might not need nearly as much low frequency management due to the limited frequency range of the human voice, where the first two octave bands would be of less interest. 



Office spaces:
In office spaces or similar environments an adequate speech intelligibility is a vital criteria. To enable speech to be heard clearly throughout a space, the room acoustician would make sure that reflections and reverberation are satisfying and meeting the demands.
The direct sound pathway vs. reflective pathways needs to have an adequate ratio to enable good clarity.
Isolation between rooms and between different zones in an open office space is often needed.
Now days the need for audio/video meetings and even audio recordings in office spaces is higher than ever, so therefor the need to good acoustics increases. 


Criterias for offices:
* Very good Speech Intelligibility
* Low ambient noise 
* A good distribution of absorptive surfaces throughout the space
* Isolation between rooms



Whatever type of room and function you might need help with, Ljudbjörnens approach is pragmatic. Most rooms if not all rooms can be acoustically improved. With that said, not all rooms would be suitable for the intended use. Some environments are more audio critical than others. The room geometry and dimensions has a significant influence on the room acoustics and the smaller the room is, the more challenges it usually has. In some scenarios clients actually have the option to choose between different rooms. Is these cases, it's wise to let an expert consult the client so that they find a suitable space. It can possibly save both time and money by avoiding problems associated with unsuitable spaces.

How much does it cost to adjust a room?

The current conditions and the construction of the space, the budget, the ambitions and the time schedule will together determine the resulting room acoustic qualities.

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Sound isolation

 

The term sound isolation is sometimes confused with the term sound absorption. These terms are different yet familiar. Let med try to explain this briefly:

Isolation of sound refers to the function of acoustically separate spaces from each other. Simplified, the term isolation describes the sound level difference between two rooms. This level difference is expressed in dB (decibels).

To properly construct an isolated two shell wall, you need thick and heavy mass, absorption material in between the two wall shells to reduce the resonances within that cavity. De-coupling as well as an airtight construction. You also need all duct work and pipe penetrations that goes through the partitions to be properly installed with satisfactory decoupling methods and suitable sound silencers. Everything has to be carefully planned and executed in order to get high isolation values. 

Sound absorption can be achieved by simply placing porous sound absorption material (glass wool for example) in a room for example. In this case, this type of absorption function is called velocity absorption. The glass wool fibers converts the friction of the air molecules to (non noticeable) heat. This same sound absorption principle is often used inside a double wall design (explained above), to improve the isolation.

Isolation in audio critical environments:
When working with music studios, cinemas, mastering facilities or other audio critical spaces, it's fundamental to consider the importance of low frequency transmission. Therefore, in the context of audio-critical environments, the dBA level values are often insufficient. Frequency weighting C or Z (filter off) should be used.

Isolation is a relative term as well as it is frequency depended, so to call a room isolated does not by itself tell you much. Sometimes you might hear the term "soundproof". Ljudbjörnen would advise against using that term because it's an overly simplified description of isolation and it doesn't present any valuable information. To get specific and to be able to validate the effectiveness of isolation, it's performance can be described as STL (Sound Transmission Loss), STC (Sound Transmission Class), Dn or Rw (Reduction Value). 

In order to get good isolation values and also subjectively pleasing results, one needs to not only reduce the airborne sound paths. It's critical to also look at impact based sound and structural sound paths as well. A sometimes overseen construction detail is making sure all interconnections through the partitions are properly installed by someone that understands basic acoustics. A badly installed ventilation duct can greatly reduce the isolation capabilities of an otherwise well constructed double leaf wall.
Also, a badly installed door (or a door that needs adjustments) within a well constructed wall can greatly reduce the whole partitions isolating ability. 

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Acoustic measurements

 

Room acoustic measurement procedures and the motivation for it:

Along with active listening in the room of interest and having discussions with the client, room acoustic measurements can be very valuable and compliment the subjective experience. By executing acoustic measurements we are getting both a numeric and a visual representation of the transfer function of the space. The transfer function is the difference between the stimulus signal sound source and that same sound source AFTER the influences of the system of interest (the space/room).
So, the transfer function is the room of interest, its obstacles, the sound source and its position together with the measurement microphone and its position in the space. 

The measurement data can for example show us the decay times (a.k.a. Reverberation Time or RT60) over different frequency bands. The data can also show us the temporal relationship between your direct sound source and the reflections. These tools are very useful when for example optimizing a critical listening environment where strong early reflections have to be either absorbed or redirected.

Our vital routines

By having consistent logging and calibration routines as well as having up-to-spec equipment Ljudbjörnen always gets reliable measurements of the space of interest.

Technical equipment:

Earthworks Audio M30 - High performance omnidirectional measurement microphone
(meets or exceeds ANSI Type 1 and applicable IEC 61094 requirements)
Larson Davis CAL150 - Class 2 sound level calibrator
RME Audio Babyface PRO FS - High-End Audio Interface
Apple MacBook Pro
REW acoustic analyzing software

Options for the stimulus signal sound source:
> Your main speakers when analyzing a critical listening environment.
> KRK 6000 for small rooms or smaller budgets.
> Dodecahedron omnidirectional speaker when doing acoustic measurements in bigger rooms and/or with bigger budgets.

Background


As an small Audio Production company, Ljudbjörnen was born in late 2010, focusing mainly on audio recording. Nisse primarily worked out of his shared studio facility in central Stockholm, Sweden.
 
Seven years later after an intensive and long recording session in 2017, Nisse got severe tinnitus. After over two years of trying to adapt to this new relationship with the concept of silence (or the absence of it), Nisse tried to adjust his type of audio related work by reducing the hours spent in sound exposuring environments. Fewer hours in the studio, less loud bands and more podcasts. 

In 2019 Nisse decided to shift focus from audio engineering to room acoustics. This was not a quick nor painless journey as it involved both patience, education and new compromises. One natural motivator that helped Nisse to develop and learn to master this new profession was his already well developed passion for good music and good sound. 

 

Protect those ears!

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