Why is Live Sound Still (Mostly) Cabled?
Most people have experienced the issues of buffer-time first-hand. Maybe you have tried enjoying some of your favourite music playing on a Bluetooth speaker, but the songs keep breaking up to load the track, especially between each song – this is what is technically known as buffer-time. Buffer-time is incredibly common on Bluetooth connections which traditionally have quite a high latency. Latency means the time it takes from the sound is transmitted – from a microphone, a musical instrument, a device playing your favourite tunes – to the sound is played by the wireless speaker. The latency of most wireless Bluetooth connections is somewhere around 200 milliseconds (1 fifth of a second) – and for sound to appear as if it is happening live, the latency needs to be below 20 milliseconds.
Because of the high latency of Bluetooth connections, wireless speakers have traditionally not been used in live-settings because of the buffer-time. Now, buffer-time is not the biggest issue if you are at home, playing your favourite tunes in the living room, but it is a very big issue if you are in a live-setting with a microphone and a person whose mouth is moving with the sound being delayed. If you try to speak into a microphone with high latency, it will feel like you are talking over yourself – sort of like when you are on the phone and can hear your own voice through the other person’s device. This is the main issue and why live event speakers have traditionally been wired – but SOWA is here to change that.
SOWA Link is SOWA’s unique low latency audio technology that allows us to connect an unlimited number of wireless speakers at once in a live-setting, making wireless live audio a possibility. This is quite a leap for the live audio industry where events would usually require wired speakers which can be time-consuming to set up, not to mention a health and safety hazard if one isn’t careful with the placement of the wires in the venue.
With SOWA Link technology for wireless speakers, the latency is below 15 milliseconds, making the sound appear as if it is happening live – that is more than 10 times faster than traditional wireless Bluetooth speakers!
SO WHY DOES BUFFER-TIME USUALLY OCCUR IN WIRELESS SPEAKERS?
Wireless speakers that connect to each other to play synchronously in multi-speaker systems communicate through radios. In this context, radio does not mean the thing in your car dashboard, but instead a chip that can send and receive wireless signals. All wireless speakers have either a Bluetooth radio or a WiFi radio to connect the speakers with eachother in multi-speaker systems. Furthermore, wireless speakers include a tiny computer, also known as an MCU, which is in charge of making sense of data that is sent between the speakers. The radios send and receive sound by transforming an electric signal into so-called data packages which are transmitted between the radios.
First, the audio is packed by the computer (MCU) on the sending speaker into data packages. Then, imagine that tiny conveyor belts run between the wireless speakers in the house. The audio data packages travel on the conveyor belts between the speakers. Once the packages arrive at the receiving speaker’s radio, they are unpacked by the tiny computer (MCU), and sent to the amplifier which translates the data to create the sound of your favourite track that plays in the speakers synchronously.
Traditionally, wireless speakers use a system called Forward Error Correction to ensure that each note of the sound playing is playing correctly across all connected speakers. Unfortunately, sometimes packages on the conveyor belts are lost, mainly due to either interference or because the distance between the sending radio and receiving radio is too great. To counteract the issue of missing packages, these can simply be sent again. The receiving speaker’s radio informs the sender to re-transmit a package that has gone missing. The package is sent again, and the receiving radio places the package in the correct order – and this is what causes buffer-time.
A different way to illustrate this, is to imagine that each speaker and device is actually people having a conversation. If two people are too far apart to properly hear each other or in a super noisy room because loads of other people are having loud conversations, it is easy to miss words. Sometimes the meaning of the sentence is even lost because the noise is too intense or the distance is too great – or both. This is how other nearby wireless connections and long distances can interfere with wireless speakers. When words are lost, the person listening will have to ask the person speaking to repeat themselves, making the conversation longer than it would otherwise be – causing, you guessed it, buffer-time.
WHAT MAKES SOWA DIFFERENT?
SOWA Link is a technology that has provided SOWA speakers with an extra reliable conveyor belt, almost guaranteeing that no packages are lost and eradicating the need for re-transmission of packages.
One of the ways we have done this is by minimising interference on our conveyor belt through our modulation form, which also allows us a larger distance between each speaker without experiencing any issues – in fact, SOWA speakers can connect with 200 metres distance between them, line-of-sight, in an outdoor setting. This is groundbreaking for wireless speakers as the range would usually cause too many packages to be lost over the long distance.
In practice, interference is what happens when you’re at a busy event and you realise you can’t use your phone WiFi because there are too many networks active at once in a small area. This is always the risk of wireless live sound – you can check that the sound works fine at a soundcheck but once you allow 5.000 people with a cell phone in their pocket into the room with the speakers, interference can mean the wireless speakers no longer work.
To counteract this issue, SOWA uses a different modulation-form than traditional WiFi and Bluetooth. While we also send on the 2.4GHz frequency, which is an internationally recognised licence-free frequency, our new technology means we experience less interference, ensuring we retain a stable connection even in a room full of mobile phones.
To understand how this works, imagine that the 2.4GHz frequency is a massive house with a large party taking place and loads of people roaming the building, speaking loudly in the same language. Again, imagine every person is actually wireless speakers talking loudly with each other. This creates a very noisy environment, which in fact is the technical term for when loads of networks are interfering with each other. Every missed word because of the noise of the party is a missed data package, requiring listening speakers to ask the talking speaker to repeat itself so they can understand the sentence – this is traditional Forward Error Correction.
But with SOWA Link technology, SOWA speakers are able to find a quiet room in the house all up below the roof, speaking a different language none of the other speakers understand. This allows conversations to flow without noise interrupting it, minimising the risk of missed packages and thereby the risk of buffer-time.
Our unique strategy to avoid buffer-time combined with our solution to the issue of interference makes SOWA Link the must-have for a fuss-free, wireless, high-quality live sound experience, which can be set up in minutes and moved around easily.
Get in touch if you are looking for more information about SOWA Link and take a look at our wireless speakers for event audio, SOWA Pro speakers here.