Dr. AIX's POSTS — 28 January 2015


Just how loud is too loud? If you’re the bassoonist in a symphony orchestra and you’re seated right in front of the brass section, you’re going to have to get used to some very loud passages in selected pieces of the symphonic literature. In a recent concert at Disney hall I actually saw musician’s head partially surrounded by a semicircular baffle. It doesn’t get killer loud very often but it does get loud. Very loud. The end of Mussorgsky’s “Great Gates of Kiev” or Stravinsky’s “Rite of Spring” can peak to 120 dB SPL plus. That means that the molecules in the air are very activated and your eardrums are moving very aggressively in sympathetic response. It’s exciting in the context of a great piece of music but it’s not dangerous for the audience (or for the players) unless it’s constant and close up. Loud passages in music are part of what make it interesting, emotional, and compelling.

And the same goes for the quiet passages. The pianissimo tremolo strings near the end of “Firebird” suite that introduce the Horn solo (French Horn…but you never refer to it as the French Horn…it’s just the Horn) is a perfect example or the snare drum the starts the famous Ravel “Bolero” are just above the level of the auditorium. The difference between the two is the dynamic range of the musical composition. In a great hall the potential for very wide dynamics is possible. A very quiet room has an ambient level of about 25 dB SPL. If fortissimo music is played, it can reach momentary peaks above 120 dB SPL…that’s real world dynamics in an ideal setting.

As a recording engineer, I want to capture the dynamics that existed in the hall during the performance. In the past, we were stuck using amplitude modification devices that ensured that our recording devices didn’t crash into the red…and distort. We couldn’t capture real world dynamics. And this applies equally well to commercial music regardless of genre. A jazz or rock drummer can hit a rim shot and blow right past the red zone easily. And singers are the worst! A trained soprano can belt out a note that registers on the Richter scale…I know I’ve recorded many opera singers and it never ceases to amaze me how quickly they can ratchet things up.

Real world dynamics cannot be captured using traditional analog recording equipment without amplitude modification…the use of compressors. However, our commercial recording industry isn’t interested in capturing or delivering real world dynamics except in the rarefied world of classical and jazz. It’s been shown over and over again that louder sells more records. As a result, compressors are used on each individual instrument as a multichannel recording is tracked, compression is used during the mixing process to get that “punchy” sound, heavy compression is used during mastering, AND compression and limiting (a harsher very of compression) is applied at the point of distribution…radio stations, satellite and processing by online channels.

It’s conceivable that consumers don’t need more than 16-bits worth of dynamic range on playback. That’s CD spec and translates to 93 (a few dB taken off of the theoretical 96 thanks for dithering). There are very few recordings that have this level of dynamic range (I know a lot of mine do…but many don’t). However, it’s critical for recording engineers to know that they can run “hotter” without worrying about overages or clipped samples. The primary benefit of using 24-bits or even 32-bits applies to production stage of music recording and means almost nothing to the delivery of “high-resolution” music. When people say they can hear the difference between 16 and 24-bits, they’re probably curing off of the noise floor and not the dynamics of the recordings.

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About Author


Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

(2) Readers Comments

  1. Mark,

    I am all for greater understanding and your evangelism for High Resolution Audio. I experienced DVD-Audio when I bought an Acura TL in early 2004 and listened to the disc that you produced for that vehicle. I immediately went and bought a DVD-Audio player, which I still have, and deployed two 5.1 setups in the house I was living in at that time. I used the Acura disc to show anybody that would give me 5 minutes, how fantastic HRA was (96/24 stereo) and surround sound.

    I have since moved and am setting up a 5.1 system in my current house and I will continue to demonstrate HRA to anyone who will give me 5 minutes when they come to my place.

    As I was reading your email yesterday, it struck me how ironic it is that you provide your daily information in a written/read format when the topic is about audio. I encourage you to consider using an audio format occasionally, with audio examples when possible. I understand the logistics and greater time/expense this would entail for you though that may be offset by the greater audience you could reach. I am not strictly speaking of a podcast as much as an audio version with example files to further make the points of your post.


    PS I suspect you use voice recognition at the moment based on some of the contextual inconsistencies so you may be part of the way there 😉

  2. PPS I realized it was Elliot Scheiner that produced the sampler DVD-Audio disc that came with the 2004 Acura TL. My apologies for the error.

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