Are you bothered by TV commercials that seem louder than the program in which they are embedded? If so, you're not alonethe Federal Communication Commission (FCC) has received millions of consumer complaints about this, and in a rare moment of bipartisanship, the US House of Representatives passed the Commercial Advertisement Loudness Mitigation (CALM) Act last Thursday, following the Senate's unanimous passage in October. According to the reports I've read, this legislation empowers the FCC to require broadcasters to adopt industry technologywhich Dolby has been working on for the last decadethat modulates sound levels and prevents overly loud commercials within one year.
Meanwhile, I wonder just how bad the problem really is. I've heard that the peak levels of commercials are no higher than those of the program content, but the dynamic range is compressed, raising the minimum level so the commercials appear to be louder. However, I haven't seen any hard data to support that assertion.
To find out for myself, I decided to take some measurements. Using my trusty Larson Davis Model 700 recording SPL meter, I set the microphone in the middle of my home theater and measured the maximum and minimum RMS levels (A weighting, slow response) in 1-minute intervals during The Simpsons Christmas Special, which aired last Sunday. The results are depicted in the graph abovethe blue bars are the maximum levels in each interval, and the pink bars are the minimum levels. The yellow-shaded regions are the commercial segments, while the unshaded regions represent the program. (Thanks to Photoshop maven Joanna Cazden for her help with the graph.)
As you can see, maximum levels in the commercial segments were no higher than those in the program segments, as expected. Also, the minimum levels in the first commercial segment were indeed higher than surrounding program regions, but this distinction is much less obvious in the other two commercial segments. Interestingly, the lowest maximum level occurred during the second commercial segment, not during the program.
Of course, this is only one sample, and I intend to do many more such measurements to see if there is any objective basis for the consumer complaints and subsequent congressional action. Meanwhile, there's always the mute button or fast forwarding through commercials on DVR recordings, both of which are SOP in my home theater.