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 a myriad of venues, each with its own unique acoustic signature. From intimate jazz clubs to cavernous 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 exceptional listening experience to the audience.

In this blog, 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 element within a venue shapes the propagation of sound.  This can also inclue the shape and size of the stage, as well as balconies and structural impediments such as pillars and varied ceiling heights. 

The Challenges

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 challenge is to provide a consistent mix for your artist no matter what the venue.

The Physical Space

The first thing we need to consider is the physical space. Is the venue inside or outside? What is the size, and shape, and what materials are present? All of these will influence the following:

Reflection and Absorption:

Sound waves bounce off smooth, hard surfaces creating reflections that can either enhance or degrade 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. 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. However, longer decay times can also create problems with intelligibility and clarity. Venues with long decay times are considered very live.

Liveliness

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. However, a venue that is very 'live' when empty during soundcheck, can become quite dead once it fills up with an audience.

Standing Waves

Standing waves occur when sound waves reflect off parallel surfaces, causing 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 whisk away the high frequencies and the sheer volume of 16,000 screaming girls can create significant challenges for intelligibility.

The Process 

The acoustic challenges you face will change from venue to venue so how do you deal with it?  

Set up the Sound System Properly

The first thing to consider is placement of the speakers.  Whenever possible, 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.  Trapazoid type speaker systesm, speakers that must be stacked, and venue constraints can make this difficult.

Acclimate Yourself

Before you begin tuning the system, listen to the room. Listen to how the room is reacting and if using the venue's in-house PA, familiarize yourself with what it sounds like.

Take the time to acclimate to your environment. Before you even start dialing in your inputs, listen to the PA system and venue. Play a familiar song on the system 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. 

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 pretty 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.

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, mitigate standing waves, and compensate for poor room acoustics, etc.

There are some great system optimization tools that assist with tuning the PA to the room. However, the learning curve can take some time and they can also be expensive. The other problem with these tools is that they can require a significant amount of time to implement them 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.  

In Conculsion

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.  

_{By:Michelle Sabolchick}