SPL Does Not Need To Be 150dB!

In this blog post, I will be critical of a live sound colleague, a fellow sound engineer. Boston.com recently chronicled an incident at a concert by the band EXTREME at the Indian Ranch concert venue in Webster, Massachusetts. The police nearly shut down the concert because the PA system was extremely loud, and there were neighborhood noise complaints. As I usually would expect neighborhood noise complaints in a post-show report, the part that stood out to me is that the head of security cited an SPL meter reading of 110dB in the sound check. If you are familiar with the sound attenuation formula and the inverse square law, a 110dB reading in the crowd or FOH means that the PA system was well beyond safety levels in the front rows. For reference, the human ear pain threshold is 120dB (the level at which your eardrum pushes the limits of dislodging and ripping). This burns me as an audio engineer who has done FOH for stadium and bar bands. This article is an excellent example of what NOT to do and how EGO has driven the sound industry.

Here are some quotes from the article from Boston.com.

"The incident occurred last Friday. Before the show, a retired state police lieutenant handling security at Indian Ranch in Webster told a local police sergeant that the band's sound was up to 110db during soundcheck. When asked to turn the volume down, Extreme's sound engineer allegedly told police that the volume "doesn't go any lower," the Telegram & Gazette reported. "

"After contacting the manufacturer of the equipment, police learned that this was not true. Police confronted the sound engineer "about his lie," and the volume was turned down to an acceptable level, according to The Boston Globe. "

"Based off his previous untruthfulness in the matter, I utilized some profanities to gain compliance, and he turned the amplifiers off. During this interaction, the sound engineer was extremely animated, frustrated, and disrespectful, at one point grabbing my wrist in frustration…Once he turned the volume 'off,' the volume was at an acceptable range that seemed consistent with the previous concerts that I've worked," Sergeant Robert Larochelle wrote in his report. 

Let's do some detective work. 

Here are photographs of the Indian Ranch Music Venue.

The space between seating rows (typical) is 36 inches. An aisle should be between 6-8 feet to allow for traffic. I will use 6 feet (that might be generous given the venue's age).

There are 37 rows in this venue with four access ways. 

(37 rows x 36” = 1332” or 111ft) + (4 access ways x 6ft = 24ft) = 135 ft total distance from stage to FOH. 

For this distance, you would roughly have an SPL loss of 40dB from the PA speaker to FOH. The math has to take the difference between two distances. I typically use 1 foot and then the maximum distance.

From: https://www.omnicalculator.com/physics/distance-attenuation

So, at the front of the stage, you would be pushing 150dB to get the sound to be 110dB 135 feet away! (Source calculations)

Morality in Live Sound Engineering

My classes discuss morality in sound engineering, especially in live sound. There will be SPL loss over distance. But, if you are dealing with a situation like this one, to get 90dB at this distance, you are sacrificing multiple people's hearing in the front rows. Let me give you some more numbers. 80 dB is typically the loudness that audio engineers listen to music. 80 dB This is a good loud volume that allows you to hear all frequencies. Anything over 85 DB will produce hearing loss or ear fatigue over time. Now, when I mean overtime, I don't mean over it the lifespan of a person, but I do mean small incremental loss of the high frequencies immediately. The more exposure to loud SPL, the more frequencies you will lose. Hearing loss isn't just a volume reduction in your ear over time; it is the loss of frequencies, especially high frequencies, that produces significant problems. Those high frequencies are what give sounds their uniqueness and also include the intelligibility of speech. When somebody who might have hearing damage or hearing loss is in a conversation, and they say "what," it's not that they didn't hear you; it's that they cannot pick up the intelligibility cues in the sentence structure to understand the meaning.

To give you some examples:

A motorcycle without the alteration of an exhaust typically runs around 90 to 95 decibels. Fifty minutes of that exposure is enough to be unsafe.

Sporting events, subway trains, and sirens typically run around 100 DB. You only need 15 minutes of exposure to produce permanent hearing damage.

Turning your air pods up to Max volume will produce around 110DB. That even starts to get painful. After 5 minutes at that decibel, you will begin endangering your ears.

120DB in overproduces instant injury. That ringing in your ears that you usually hear after a rock concert means that you have hearing loss in some frequency band. Go to enough of them, and you'll start to notice it at an earlier age.

(https://www.audiologyassociates.com/hearing-loss-articles/what-sound-level-is-safe-for-listening/)

So when I speak of morality, pushing that stereo master fader higher means that YOU are subjecting many people to hearing loss. Now the argument from people who are not sound engineers is, "well, that's the risk concertgoers inherently understand when they go to a concert." I call bunk. 

The one controlling the sound is you. You single-handedly control that output fader and thus have a moral obligation to ensure the safety of every audience member. You have morally failed if you push SPL limits beyond the threshold of pain for even three rows of seats. There is no redo. Those people in the front rows have permanent hearing damage caused by you. It might be small and perhaps unnoticeable at the time, but those people will have conversation issues later in life. They might not remember the concert, but that issue would arise from even exposure due to your PA system.

The devil's advocate

Some concertgoers' peer pressure about wearing earplugs or listening to softer music will always be there. A concertgoer should not have tinnitus at the end of the show. And the thought that listening to lower levels of music ruins a concert experience because "I cannot feel the music" is also asinine. The kick drum or bass low-frequencies have way more energy than 110 or 120 SPL. The moving air feeling" that concertgoers get from subwoofers still damages their hearing. The inner ear works in a way that, to be heard, low frequencies pass by the high-frequency hairs. The high-frequency cilia are getting bombarded by both high-frequency SPL and low-frequency SPL. This anatomical design is why we tend to lose high frequencies first over time.

"Earplugs don't make me look cool."

This toxic machismo rhetoric must stop. I still enjoy a concert with my high-end earplugs. Do I look cool? Yes. My reply is, “do you wear ear protection when discharging a firearm? Then yes, you should wear earplugs because this music is just as loud”.

"This is the way we have always done it."

Hogwash. Throughout history, procedures have changed because we have found better and safer ways of doing things. Society does not parent as we did back in the 1800s. We as a society do not drive cars as we did in the 1920s. We do not have the same healthcare system we did in the 1800s. So let's stop this rhetoric and show the older generations that there is a better way to do things that generate more revenue. 

The Solution

So what is the solution, you ask? It's pretty simple. You should be mixing around 80 to 85 DB at the front-of-house position. Your front-of-house position should be close enough that, at maximum, the front rows are experiencing 90 to 95 DB. this means that during a typical set break, the audience members are only getting 50 minutes of exposure. Again that's not ideal, but that is a compromise. If there are seating rows behind you, you must install fills to keep the sound at 80 to 85 DB in the entire venue. One set of speakers at the front of the stage is never enough for a big concert. There are always fills. They are morally compromised if your venue refuses to install or pay for fill speakers. The venue cares not about the music or its patrons but solely about profits. Why wouldn't audience members want to hear the music in the full spectrum? 

Every concert venue should provide hearing protection. The foam plugs are not ideal as they do attenuate high frequency. But it is something. We need also to change how concert venues distribute those earplugs. Venues cannot hide hearing protection in guest services. They must be given to every audience member upon entry at the gate. But is this too expensive? I call bunk again. The distribution of hearing protection is a cost of doing business items and is thus tax deductible. I'm sorry if you're worried about the cost, and your profits are that high, then buy some stock in the ear plug manufacturer. That way, you take the tax deduction on the business expense of purchasing earplugs, but then you see increased profits in your stock profile from that company. And if the concert venue won't distribute earplugs, then you, as the sound company, should. Isn't that your moral obligation? Wouldn't you gain more fans and followers if you had a branded earplug?

Conclusion

You have a moral obligation to protect all members of the concert experience. From musicians on stage to the six-year-old kid in the last row, you, as the A1, have sole control over the output of the main speakers. Having listening levels that are too loud and produce hearing damage over exposure time means you morally failed part of the concert-going experience. As a professional, you are obligated to educate yourself, understand the limits of your system and human anatomy and figure out a way to deliver the best SAFE concert experience to all involved. 

Dr. Mike Testa