Understanding Venue Acoustics: Adapting to Different Spaces

Managing venue acoustics in live events can be a challenging skill to master, but it is a necessary one for live sound engineers.

Sound engineers often find themselves navigating many different types of venues, each with its unique acoustics. From intimate jazz clubs to spacious concert halls, outdoor festivals on open stages, to buildings full of glass, concrete, and steel, understanding how sound behaves in different spaces is essential for delivering an enjoyable listening experience to the audience.

In this article, we'll delve into the intricacies of venue acoustics, exploring the principles, challenges, and strategies live sound engineers need for adapting to diverse sonic environments.

The Science of Venue Acoustics

For our purposes, venue acoustics takes into account how sound waves interact with the physical characteristics of a space. From the reflective surfaces of walls and ceilings to the absorptive properties of seating and flooring, each of these elements will influence how the sound reacts in the space. This can also include the shape and size of the stage, as well as balconies and structural features such as pillars and varied ceiling heights. 

The Struggle is Real

What makes venue acoustics so challenging is that no two venues are alike, each presenting its own set of acoustic characteristics and challenges. As a live sound engineer, you may be mixing in a nightclub one night, an outdoor stage the next day, and a symphonic concert hall the day after.  The goal is to provide a consistent mix for your artist no matter what the venue.  Even mixing multiple nights in the same venue can yield different results.  For example, if the room is very ‘live’ with a lot of reflections and the first night is sold out with plenty of bodies to absorb those reflections, this can lead to an improvement in the venue acoustics.  But on the second night, the venue is only half full- same venue, same band, same show, but fewer bodies to soak up the reflections.  It may not sound drastically different but it won’t sound exactly the same.  This often happens in outdoor venues when you factor in temperature and humidity changes throughout the day. 

When approaching venue acoustics, one of the first things we need to look at is the physical space. 

• What materials are present? 
• What is the size and shape?
• Is the venue inside or outside?
• What is the coverage area needed for PA? 

All of these will influence the following:

Reflection and Absorption:

Sound waves bounce off smooth, hard surfaces creating reflections that can either help or hurt the listening experience. A room full of glass windows and steel beams will be much more reflective than a room with heavy drapes covering the walls and an acoustically treated ceiling. Sound will also reflect off balconies and structures like pillars or columns.  Absorptive materials, such as curtains or acoustic panels, help mitigate excessive reflections which factor into the reverberation time of the venue.  

Reverberation time:

The natural decay time of a room, often expressed in seconds, refers to the duration it takes for sound to decay to the point where it is no longer audible after the source ceases. Large, reflective venues like concert halls often have longer decay times and this can contribute to a sense of spaciousness and warmth in the mix. It helps make an electric guitar sound huge versus small and boxy as if it were being played in your basement.  Longer decay times can also create problems with intelligibility and clarity. 

Venues with long decay times are considered very ‘live’. The reflections from surfaces factor into the liveliness of the venue. High frequencies can be problematic in a room full of glass and hard smooth surfaces, becoming much more noticeable with nothing present to absorb them. This can create problems on stage when those reflections are being picked up and amplified through the vocal microphones, sometimes causing feedback.  However, a venue that is very 'live' when empty during soundcheck, can become quite dead once it fills up with an audience.  

Acoustically treated venues tend to be more manageable. Outdoor venues without walls and a ceiling (open air), lack surfaces to create reflections providing a  ‘dry’ or ‘dead’ sounding environment.  In a dead room, you may find the need to add more reverb than usual to bring the mix to life.

Other factors

Standing Waves:

Standing waves occur when the sound wave hits a parallel surface at a distance equal to the length of the wave.  The wave reflecting off the surface combines with the wave coming from the source and creates constructive or destructive interference at specific frequencies. 

Identifying and addressing standing waves is crucial for achieving a balanced frequency response and minimizing unwanted resonances that can muddy up a mix.

Environmental Factors:

External factors, such as ambient noise from HVAC systems or street traffic, even a noisy audience can significantly impact the acoustic environment within a venue. A substantial wind at an outdoor show can have an effect on high frequencies and the sheer volume of 16,000 screaming girls can create significant challenges for intelligibility.  Temperature and humidity changes will also have an influence.

All of the elements affecting acoustics will change from venue to venue so how do you deal with it?  

The Process

The first step is to:

1- Set up the Sound System Properly

PA Placement- Point the boxes at the people

The first thing to consider is the placement of the speakers.  They should be aimed at the audience and away from walls, ceilings, and other hard surfaces.  Modern line array systems can be 'steered' physically, and sometimes in the components themselves, to send the acoustic energy where you would like it- on the bodies of the audience. This is not always possible.  Trapezoid type boxes, speakers that must be stacked, and venue design can at times make this difficult.  

The speakers should be downstage of the band.  This should be obvious but sometimes the goal in venue design is to be aesthetically pleasing rather than acoustically correct. You’ll often find this in small venues where the installation of a sound system was an afterthought.

In large venues with flown systems, aim to keep the coverage on the audience and off of the walls and ceiling as much as possible.  There is no need to have the top three boxes of the PA hitting the back wall 10 feet above the audience’s heads. 

2- Component check and System optimization

It is always recommended to do a system component check and noise the system to make sure everything is working correctly before you start tuning.  Proper time alignment between Mains, Subs, Front Fills, Delays, etc. is also important.

This should be done by the system engineer and a good SE will be well versed in how to correctly optimize the system.  I’m not going to go into much detail on system optimization as the topic could fill volumes.  There are some great system optimization tools that assist with tuning the PA, however, the learning curve can take some time and they can also be expensive. The other problem with these tools is that those who are just getting started with them can require a significant amount of time to implement properly to receive accurate results. In the fast-paced world of live events, time is something that is regularly in short supply and very often sound engineers have only a few minutes to tune the system. 

So my advice is to learn how to quickly tune the system by ear.  

How to do it:

First Acclimate Yourself

Before you begin tuning the system, take the time to acclimate to your environment.  Play a familiar song through the PA and walk the audience area while you listen to how the room reacts to the PA. Things will often sound different as you move around the venue.  Familiarize yourself with what the speakers sound like and what the room sounds like.

Listen to the various zones individually- the main speakers, front fills, delays, under-balcony speakers, etc. Then listen to the system as a whole.

Is the balance correct? Are there hotspots? Do the subs create a power alley down the center of the venue? Make the necessary adjustments to get the balance right before you start tuning the PA.

You can start acclimating from the minute you walk in the door. If you are standing at FOH and can clearly hear the conversation from the stage 50’ away, that’s your first sign that you have got a lively room that may require some finessing on the high end. Listen to the natural sound of the space.

As you become more experienced, you’ll start to recognize the characteristics of various PA systems and how they differ. From Meyer to L-Acoustics, d&b, and JBL, each has its own recognizable sound, and familiarity will make it easier to identify if what you hear is coming from the room or the PA.  For example, whether that honky mid-range is inherent in the speaker or the acoustics of the venue.

Which brings me to:

Tuning the PA

The goal is to achieve clear, undistorted, balanced, high-quality sound throughout the entire listening area. After setting the proper balance of the PA, you'll want to tune it for the room and the needs of your show. Smooth out any harsh or unwanted frequencies, sort out standing waves, and make adjustments for poor room acoustics, etc.

A very simple way to do this is to create a playlist of songs that you are very familiar with and mixed well.  Ideally, songs you have listened to many times, so that when you listen to them on the PA you’ll recognize anything that sounds off. These songs are for your reference.  For example, if the low end isn’t as tight and punchy as you remember, you know you need to do some work on the low end of the PA, whether adjusting the time alignment and/or EQ.  If there is a lack of clarity, you might need to adjust the EQ to clean up the muddiness.  Once you get things dialed in, it’s also a great idea to ring out the lead vocal mic in the PA.  You can do this by speaking through the microphone yourself at FOH or asking someone to do it from the stage (an audio tech, backline tech, monitor engineer, etc). This will allow you to remove any problem frequencies caused by room acoustics.

This requires ear training and a solid understanding of frequencies which is something I teach in depth in my course LISTEN!

After listening to a few songs and ringing out the mic, you should be acclimated to how the room sounds and have made any necessary adjustments to the system to achieve your goal of clean, clear, and consistent mix from venue to venue.

Managing venue acoustics is a crucial step in providing a high-quality listening experience.  Live sound engineers should understand how the physical and environmental properties of a space are affecting the sound.  Knowledge of the techniques used to manipulate the audio output of the sound system is essential to managing many different types of environments.  

If you’d like to learn more about mixing live sound check out Mixing Music Live.

By: Michelle Sabolchick