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What is RT60 and what is it used for?


Sound is made by pressure waves. Those waves spread from their starting point and bounce around walls, ceilings, floors and every surface, losing energy over time.We call that reverberation, which can...Click to read more...

Sound is made by pressure waves. Those waves spread from their starting point and bounce around walls, ceilings, floors and every surface, losing energy over time.

We call that reverberation, which can be translated as the resonance or reflections of sound after the original is produced.

Sound waves producing reverberation
Sound waves bouncing and producing reverberation

So, depending on the noise and the room, sound decays at different speeds, depending on frequency and design of the space. This means that longer reverberation times will become unintelligible sounds, depending on the space and types of sound.

The length of this decay is called Reverberation Time.

So, to measure the time that sound takes to be inaudible, we use a method called RT60. The time it takes to reduce sound pressure level by 60dB. For example, if the sound in the room takes 5 seconds to decay from 100dB to 40dB, the RT60 is 5 seconds. This measurement using 60dB is not arbitrary. It is the typical range of dynamic levels for orchestral music.

So to measure RT60 we use a sound level meter with acoustics measurements to reach a number before treatment. At JOCAVI, our acoustic simulator, JAS, can make an average estimate of your RT time, given the size of the room.

The measurement of RT60 is used to find a value for acoustic treatment. Depending on the intended use for the room or space, it should have different optimal reverberation times. If a room has too many absorbent materials it is described as acoustically ‘dead’ and, if the opposite occurs, it is acoustically ‘live’.

Of course there is an optimal range for reverberation times in different spaces and below you can see a graph made by JOCAVI to better understand the process. If you want to know more about the calculations of this process, please click here.

Acoustic environment of various types of rooms

Note that this measurement is an average. Also, it implies the decay is exponentially, which sometimes is not the case, depending on the disposition of reflective, dispersive or absorbing surfaces. More about the principles of reverberation here.

If you still have any questions or want to know what can a good and balanced acoustic treatment do for you, contact us at info@jocavi.net


JOCAVI is made for you!


If you need a custom stylish treatment panel to make your room unique, you can rely on JOCAVI.We know style and performance go hand-in-hand, so JOCAVI can make the room of your dreams stand out.You do...Click to read more...

If you need a custom stylish treatment panel to make your room unique, you can rely on JOCAVI.

We know style and performance go hand-in-hand, so JOCAVI can make the room of your dreams stand out.

You don't have to settle for DIY acoustic panels or budget solutions like shallow and small cheap panels that will make little to no difference in the overall noise reduction and control - giving you that feeling of being inside a packing box - if you can rely on professional grade materials and experience. If you want to reduce the noise in your room, office or studio, talk to us and we'll build a perfect acoustic panel to soundproof your space of choice, using high quality acoustic foam.

And if you want a unique look, we have a printable option that we call Motif®, that keeps the same acoustic performance as the original ADDSORB®, LEAKY FM®, MELLOWALLTRAP®, LIGHTWALLTRAP®, CONVEXABSORBER®, EBONY®, BASSCORNER®, ROUNDBASSCORNER®, WALLTRAP®, BASSLAYER®, MELLOWAFFLE®, TUBABSORBER® and SY® models. Custom made with images of your choice up to 1080dpi. If you want to change the image after a while, we can do that for you too. The prints can be made on fabric, canvas or wood.

From diffusers to absorbers, we have over 1100 possibilites between high quality products, with different materials, colors and finishings on our catalogue but we can make even more, with the dimensions and finishings of your preference.

Contact us!

motif living room


How to make your own home studio


Do you sing, play some instruments, want to record podcasts, maybe get into production and don't know the steps you must take to create your own home studio, we're here to help!The best way is to take...Click to read more...

Do you sing, play some instruments, want to record podcasts, maybe get into production and don't know the steps you must take to create your own home studio, we're here to help!

Home studio essentials

The best way is to take it from one end to the other, so let’s start with the voice. You will need a microphone with a stand so you won’t have to keep one hand occupied holding it forever. The type of microphone you choose depends on what sound you want to capture and, of course your budget. That will be a recurring theme. So let’s get a large diaphragm condenser mic for starters. It is ideal to capture voice and instruments keeping the clarity and precision needed for a good sound capturing.

JOCAVI VOCAL MIC REFLECTION FILTER is an acoustic bell for microphones that insulates from room effect. An easy and cheap solution that connects directly to the mic stand, shielding the capture without influencing the coloring or polarity of each microphone.

Vocal Mic Reflection Filter

Now you want to get your voice inside the computer. Well, and you have to get a PC or Mac with a DAW or Digital Audio Workstation for music production, or at least a software that will let you record and edit sound. Next you'll need an audio interface, to convert our microphone's analog signal into a digital one. Our condenser microphone will also need some power, called phantom power, and for that the Audio interface will be good to. This interface can also be a mixer or if you want to spare some money and only need to record voices for podcasts, you can buy a USB microphone that will connect directly to the computer.

Now, we guess you want to hear what you’re recording. You will have to buy a set of headphones and nearfield monitors like these JBL Control One. The nearfield monitors, designed to be listened to in a close range can be placed on stands or over your desk. We have special anti vibration bases, the NEARFIELD BASE or SUBWOOFER BASE if you have a subwoofer to improve your low end frequency listening, that you can adjust in a vertical angle. These accessories are essential to reduce vibration from the speakers that resonate through the desk or floor.

Nearfield base

But all that equipment can be near useless if you don’t have an acoustically treated room. If your room is bare and full of echoes you can get one of our ATP room packs or get some of JOCAVI’s acoustic panels.

The ATP Pack (01, 02, 03, 04, 05 and 06) is a standard pack of absorbers and diffusers made for rooms from 9m2 up to 40m2. Designed to provide acoustic comfort for home cinema, music rooms, recording, rehearsing or control rooms, it is a mix of products for those who want an off-the-shelf, pre-designed solution.

BABS

You can also contact JOCAVI and we can build a custom made solution for you. With over 1.100 product variations we have the perfect products for your needs.

Now you have a basic home studio set. A microphone that connects to an audio interface that goes into the computer's software to record and produce and a set of speakers so you can listen to the results. But of course there is more!

When you need to phisically and acoustically separate your home studio you can use our portable acoustic blind set, the BABS. Ideal to provide an outstanding acoustic division between each instrument or amplifier, optimizing the separation between microphones during sound capturing. It can be used to improvise a rehearsal, recording or control room. It comes in sets of two and it has two different acoustic sides that you can work to adapt the room to your intended purpose.

Drumbase

If you have a drum set, JOCAVI has more products that can improve your sound. Our KICK PAD KIT comes with Punch Master, an accessory that allows the control of the bass drum head vibration accentuating punch and beat. It also offers protection against tearing from cables. The DRUMBASE is a very easy to assemble, specially made anti-vibration platform with 4m2 that will be more efficient than the classic rug, to stop reverberation and optimize the sound of your drum kit.

Once more in bullet points:

  • Acoustic treatment by JOCAVI
  • Microphone
  • Audio interface
  • Computer with editing/recording software or DAW
  • Nearfield monitors (and headphones)


Case Study - Hasseris Gymnasium


The Hasseris Gymnasium & IB World School is a high-school founded in 1970 in Aalborg, Denmark.Designed in the modernist style, it has approximately 800 students each school year.The main issueInside t...Click to read more...

The Hasseris Gymnasium & IB World School is a high-school founded in 1970 in Aalborg, Denmark.

Designed in the modernist style, it has approximately 800 students each school year.

The main issue

Inside the school there is a multi-purpose hall whose sloped design is iconic and features in the school’s logo, being a central point for many activities and presentations like music shows, exams or graduation ceremonies. But that slanted design comes with a set of acoustic problems, with its high ceiling producing lots of reverberation. The RT60 measured before the acoustic treatment was in place was 1.84 seconds.

To solve the issues in this room, Claus Hansen from AudioExperts found a simple yet unique solution. He created a wedge made of mid and high frequency absorbers with low frequency absorption inside the custom made frame.

The proposed solution

Claus Hansen started as an Electronics Engineer and has more than 30 years of experience with professional audio loudspeaker systems, sound and acoustics, being a JOCAVI partner since 2006. An expert in our products, Hansen proposed some of JOCAVI’s ADDSORB REV absorber panels, mounted on the side walls in an angled design, and BASSLAYER panels on the back wall.

The ADDSORB REV was mounted in specially made aluminum stands to create an effective noise reduction solution and a balanced sound, enhancing both human communication and musical sound. These special stands were also designed to accommodate tuned panels inside the triangle shape to absorb the more problematic frequencies measured before treatment.

The results

This solution completely supported and designed with JOCAVI created a very balanced noise reduction spectrum, achieving 1.08 seconds of RT60 average and a staggering 41% of RT reduction. Below you can see the measured frequencies before and after inside the space. Note the huge difference around the 1000Hz.

JOCAVI has over 27 years of experience in acoustic treatment projects for large spaces, always finding an aesthetically pleasant solution with cost in mind. You can find our products in auditoriums all around the world, from east to west, north to south, and every project is unlike any other.


What is acoustics?


"Acoustics is the branch of physics that studies sound. Sound is a wave phenomenon caused by a wide range of objects and sound sources, which is propagated through the different physical states of mat...Click to read more...

"Acoustics is the branch of physics that studies sound. Sound is a wave phenomenon caused by a wide range of objects and sound sources, which is propagated through the different physical states of matter.

In acoustics we can generally divide between sectors: sound generators and means of sound transmission, propagation and reception.

Acoustics analyzes these means, creates instruments and tools, quantitative tables, etc. in order to provide the necessary data or solutions for a variety of branches of intervention so that the means of sound propagation and any defects are envisaged and contemplated through duly studied solutions.

The chain of acoustic emission and reception of sound (noise) includes the person who receives the sound effect and the event that gives rise to the phenomenon. Acoustics is considered a science that covers diverse disciplines and which is also covered by them."

These are some words from the upcoming book written by the CEO and founder of JOCAVI, João Carlos Vieira, explaining the basics of acoustics. JOCAVI is an expert in the field, with over 27 years of experience and completed projects all around the world, so you can rely on our knowledge to make your own project come to life.

That is why JOCAVI developed its own Acoustic Simulator (JAS) where you can make a room simulation and see what quality acoustic treatment can do. You just have to know your room measurements and materials and then you can test the difference in reverberation time (RT60). Note these are merely estimates to help you understand the huge impact professional acoustic treatment materials can have in leveling the noise in your room of choice.

Of course you don't even have to know a thing about acoustics! Just contact us and our project and sales teams will build you a custom solution or refer you to one of our nearest partners that can help you to make your dreams come to life.

.


SmartAV home cinema showroom by JOCAVI


If you want to build a home cinema you need to correctly address your room acoustics. There is no use in buying top-of-the-line equipment without controlling your flutter echoes and balancing noise le...Click to read more...

If you want to build a home cinema you need to correctly address your room acoustics. There is no use in buying top-of-the-line equipment without controlling your flutter echoes and balancing noise levels.

SmartAV has been working with JOCAVI for 20 years, designing and building custom home cinemas and Hi-Fi listening rooms for clients that with high demands that want the best materials and products.

Nuno Teixeira, audiovisual and electroacoustics consultant at SmartAV, says that JOCAVI’s know-how, project solutions and designs have added value to the clients, because they know they have a tailored project matching their expectations.

We went to SmartAV’s new home cinema showroom, built with four products from our range that show some of the different options JOCAVI can provide.

SmartAV Home Cinema 2  SmartAV Home Cinema 1

As always in an acoustic treatment, the idea is to balance the room and provide a pleasant listening experience, but in this case, we also wanted to showcase different types of products and finishings you can choose, from over 1100 possible options made by JOCAVI.

The products in use were BASSLAYER® bass traps, tuned to 160Hz with fabric finishing, ADDSORB REV®, a wood veneer panel to improve absorption on mid-range frequencies, SEAFOAM® absorbers with velvety finish that maintain physical properties over a wide temperature range and LIGHTWALLTRAP® with MOTIF® custom prints, a bespoke solution to achieve a unique look to every project.

These and many more product designs and options are available at jocavi.net

Check out the video below.


Interview with Dave Malekpour from ProAudioDesign at Summer NAMM


....Click to read more...

Join us in New York


This year we'll be partnering with Professional Audio Design in a larger, more visible and integrated booth where you'll be able to see our products being used in real enviroments!It will be a booth w...Click to read more...

AES New York 2019

This year we'll be partnering with Professional Audio Design in a larger, more visible and integrated booth where you'll be able to see our products being used in real enviroments!

It will be a booth with a closed space simulating a studio where you'll be find JOCAVI's eye-catching acoustic panels, Augspurger's impressive speakers, AMS Neve's amazing consoles and Sontronics world class british design microphones, all wrapped up with Professional Audio Design's knowledge of studio development and implementation.

AES Conventions are held annually in both the United States and Europe and are the largest gatherings of audio professionals in the world. Workshops, tutorials, technical papers and the trade show floor provide attendees with a wealth of learning, networking and business opportunities.

From October 16th to the 19th meet us at AES New York. 


Build your artist project studio - JOCAVI presentation at H.O.M.E.


....Click to read more...

What is comb filtering?


The filtering function that arises when a signal is added to itself after having delayed in time is called a comb filter. The resulting frequency response resembles a comb, hence the name.Two 500Hz si...Click to read more...

The filtering function that arises when a signal is added to itself after having delayed in time is called a comb filter. The resulting frequency response resembles a comb, hence the name.

Two 500Hz sinusoidal tones added. The second is delayed by 1ms, hence the sum is zero. Two 1kHz sinusoidal tones added. The second tone is delayed by 1ms, hence the sum is the double (+6dB).

The comb filter function is almost never intentional, but it is heard all the time in sound productions, where it can arise both acoustically and electrically. Acoustically, it typically occurs when the sound on its way from source to receipient takes in part a direct path and in part an indirect path via a single reflective surface. The reflection must be attenuated at least 10dB and preferably 15dB in order for it to not have an effect on the sound field at the recipient position. Electrically, the phenomenon arises when two microphones with a certain distance between them capture the same signal at the level from each microphone is of the same order of magnitude.

Two typical situations in which comb filters arise, either acoustically or electrically.

In genera: All digital signal processing takes time. Thie means in practice that comb filter effects can arise if you loop a signal via, for example, a compressor and combine this signal with the original.

dB Level Frequency - Hz

An example of a comb filter created by the combining of two signals with the same amplitude, but with a time delay between them of just 1ms.

It can be seen in a dip occurs due to cancellation at 500Hz, 1.5kHz, 2.5kHz, etc. It can also be seen that the two signals add to double their value (+6dB) at low frequencies and with a full wavelength's delay at 1kHz, 2kHz, 3kHz, etc.

Dip Frequency

Cancellation occurs for a comb filter at all the frequencies where the two signals are in opposite phase. This occurs when the time delay comprises duration of \frac{1}{2}, 1 \frac{1}{2}, 2 \frac{1}{2}, etc, periods. At 1kHz the period is 1ms. Half of the period is 0.5ms. If a time delay of precisely 0.5ms occurs, it means that cancellation will arise, not just at 1kHz, but also at 2kHz, 3kHz, 4kHz and so on.


How do standing waves influence sound fields?


The maxima of the standing waves are shown in the figure. The curve expresses the area of the room where the actual frequency is audible. At the minima the frequency is represented at a much lower lev...Click to read more...

The maxima of the standing waves are shown in the figure. The curve expresses the area of the room where the actual frequency is audible. At the minima the frequency is represented at a much lower level (sometimes – 40 dB compared to the maximum).

If the room has the same dimensions as length, width, and even height it is very problematic to obtain an even sound distribution.

How to prohibit standing waves?
Parallel walls in the room should be prevented. Then the strongest modes are suppressed. When placing the monitors it is important that as few modes as possible are excited. This is why the monitors should not be placed in a maximum of a standing wave. At low frequencies a monitor can be considered as to radiate the sound energy in all directions.

Also known as  radiation.

Also known as  radiation.

When placing the monitor close to a solid boundary – for instance a wall – the sound energy that should have been radiated in the direction of the wall instead is radiated into the free half space. Hence the sound pressure is doubled in the half space, which yields +6 dB.

When placing the monitor close to a solid boundary – for instance a wall – the sound energy that should have been radiated in the direction of the wall instead is radiated into the free half space. Hence the sound pressure is doubled in the half space, which yields +6 dB.

Also known as  radiation.

Also known as  radiation.

Placing the monitor against two boundaries – for instance in a corner limited by two walls – it is now radiating to the quarter space. Now the sound pressure is doubled twice, which yields +12 dB.

In practice, the placing by barrier walls, or ground, influence the frequency range below 125-150 Hz.


What are room modes?


The special frequencies are also called room modes. Standing waves between parallel walls are called axial modes. Other modes exit. For instance tangential and radical modes. (See the illustration). N...Click to read more...

The special frequencies are also called room modes. Standing waves between parallel walls are called axial modes. Other modes exit. For instance tangential and radical modes. (See the illustration). Normally the axial modes are the strongest.

Axial
Tangencial
Radial

The standing waves are characterized by having a maximum sound pressure at the boundaries of the room. Depending on the frequency there are one or more dips across the room. In a box shaped room the frequencies can be calculated as follows:

where :
f = frequency in Hz
c =speed of sound (approx. 340 m/s or 1130 ft/s)
l = length of the room
w = width of the room
h = height of the room
n = integer from 0 and up


What is the Sabine formula?


Wallace Clement Sabine is the father of modem acoustics. He found that reverberation time is described by a relationship between the room size and the amount of absorption in the room. Larger rooms – ...Click to read more...

Wallace Clement Sabine is the father of modem acoustics. He found that reverberation time is described by a relationship between the room size and the amount of absorption in the room. Larger rooms – longer reverberation. More absorption – shorter reverberation.

T = 0.161 \times \frac{V}{A}

Where:

  • T = Reverberation time in seconds
  • V = Volume in cubic meters (m3)
  • A = Absorption in square meters (m2) Sabine
  • 0.161 is a constant (to make the calculation correct with the actual units

Note: One square meter (1 m2) Sabine is comparable to an open window with an area of one square meter:

The sound that hits the window will disappear and never return. One square meter Sabine is one square meter with full absorption. The basic formula sounds simple, but the problem is that the materials in the room will absorb differently at different frequencies. The absorption may range from nothing (fully reflective) to total absorption.

A proper reverb time should be constant with frequency, but this is not always the case because of the behaviour of the materials in the room. The low frequencies are the most difficult to control.

This is why the reverberation time against frequency in practice may look like this:

Reverberation time measured in a control room. From 250 Hz and above the curve is nicely placed around 0.3 sec. But bellow the reverb time rises to 0.75 sec. which is too much.


What are reverberation times?


   The reverberation time measurement is defined by the time it takes a sound to attenuate 60 dB after the source is stopped. In the real life we can experience reverb times from approximately 0 sec. ...Click to read more...

   The reverberation time measurement is defined by the time it takes a sound to attenuate 60 dB after the source is stopped. In the real life we can experience reverb times from approximately 0 sec. (outdoors or in anechoic chambers) to something like 10 – 12 sec. In special reverb chambers the time may exceed 20 sec. Control rooms normally should have a reverb time around 0.2 – 0.3 sec.

Why do we have reverberation? The speed of the propagating sound wave is very slow – at least compared to light: approx. 1130 ft. or 340 m per sec.

If there are no reflecting surfaces between the sound source and our ears, only the direct sound is heard and there is no reverberation.

If there is a single reflecting surface we may hear the reflected sound in one way or another, but there is still no reverberation.

If the sound is generated in a room, there are a whole lot of reflections. Each of these travels different paths with different distances on the wayto the receiver. Each time the sound hits a surface it may loose some energy if the surface is absorbing.


One sound source, one receiver and no room.
Only the direct sound is received.


One sound source, one receiver and one reflecting surface. The sound is received twice. (In the control room this is normally experienced as comb filtering, see later).


One sound source and one receiver in a room. The sound impulse is reflected in many surfaces. All the reflections are melting together and heard as reverberation.


Table of contents

  • What is RT60 and what is it used for?
    September 25, 2020
    By Tiago Crispim
  • JOCAVI is made for you!
    August 25, 2020
    By Tiago Crispim
  • How to make your own home studio
    August 3, 2020
    By Tiago Crispim
  • Case Study - Hasseris Gymnasium
    June 30, 2020
    By Tiago Crispim
  • What is acoustics?
    June 15, 2020
    By Tiago Crispim
  • SmartAV home cinema showroom by JOCAVI
    June 3, 2020
    By Tiago Crispim
  • Interview with Dave Malekpour from ProAudioDesign at Summer NAMM
    February 11, 2020
    By Luis Roquette Valdez
  • Join us in New York
    October 4, 2019
    By Tiago Crispim
  • Build your artist project studio - JOCAVI presentation at H.O.M.E.
    September 11, 2019
    By Luis Roquette Valdez
  • What is comb filtering?
    December 11, 2018
    By Luis Roquette Valdez
  • How do standing waves influence sound fields?
    September 3, 2018
    By Luis Roquette Valdez
  • What are room modes?
    August 21, 2018
    By Luis Roquette Valdez
  • What is the Sabine formula?
    August 6, 2018
    By Luis Roquette Valdez
  • What are reverberation times?
    July 20, 2018
    By Luis Roquette Valdez

Contacts

JOCAVI International
Av. Pedro Álvares Cabral
Sintra Estoril V - B18
2710-297 Sintra, Portugal
Tel: (+351) 21 924 30 97
Email: info@jocavi.net
JOCAVI USA Corporation
28 Paris Street
07105 Newark, NJ, US
Tel: +1 (973) 536 18 32
Tel: +1 (917) 294 34 11
Email: info@jocaviusa.com

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JOCAVI™ International

Av. Pedro Álvares Cabral
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2710-297 Sintra, Portugal
Phone: +351 21 924 30 97
www.jocavi.net | info@jocavi.net
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JOCAVI™ USA Corporation

28 Paris Street
Newark, NJ 07105, USA
Phone: +1 (973) 536 18 32
Cell: +1 (917) 294 34 11
www.jocaviusa.com | info@jocaviusa.com
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Note: JOCAVI™ accepts no responsibility for any printing or display errors. The colours shown are only a reference and an illustration of the products finishing. The colours shown are not binding because brightness, contrast and colour balance may vary due to the printing process. Colours may vary due to raw-material suppliers' changes and some differences may occur in tonal range. Due to its natural origin, wood-based products will always present natural imperfections inherent to its organic nature. For similar reasons, they will also present traces of old-age in the course of time. JOCAVI™ cannot guarantee that the colours represented will exactly match the colours of the products shipped, due to the variances among different monitors and printers. Some colour variation may occur between production runs of Acoustic Foam products. Colour consistency in similar products is not guaranteed, some nuances can happen. Colour fading will occur with UV exposure over time. RAL is an international independent colour standard system partner for industry, trade, architecture and design and should be consulted before placing any order.
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Note: JOCAVI™ accepts no responsibility for any printing or display errors. The colours shown are only a reference and an illustration of the products finishing. The colours shown are not binding because brightness, contrast and colour balance may vary due to the printing process. Colours may vary due to raw-material suppliers' changes and some differences may occur in tonal range. Due to its natural origin, wood-based products will always present natural imperfections inherent to its organic nature. For similar reasons, they will also present traces of old-age in the course of time. JOCAVI™ cannot guarantee that the colours represented will exactly match the colours of the products shipped, due to the variances among different monitors and printers. Some colour variation may occur between production runs of Acoustic Foam products. Colour consistency in similar products is not guaranteed, some nuances can happen. Colour fading will occur with UV exposure over time. RAL is an international independent colour standard system partner for industry, trade, architecture and design and should be consulted before placing any order.