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CONNECTED LOUDNESS NORMALISATION FOR PODCAST STREAMING: New Tools for the Optimal Listening Experience by Jon Schorah F or media companies steeped in traditional workflows, the exploding demand for over-the-top (OTT) content on many different devices is offering up significant new opportunities as well as challenges. If content owners can re-purpose their assets effectively, they can reach existing and new audiences through channels that didn’t even exist. decade ago. Although multi-screen video content is currently making all the headlines, there’s also tremendous demand for audio-only OTT programming ranging from music and audiobooks to podcasts of popular radio shows. Re-purposing audio for streaming and podcasting that was originally mixed for broadcast is not for the squeamish. There are key challenges related to audio quality and listener satisfaction, not the least of which is intelligibility in often less-than-ideal listening environments (think subway cars and park benches). Other factors come into play, such as the quality of the user’s ear buds or laptop speakers, or lack thereof. Also, podcasts often utilize data compression techniques in order to maximize the use of limited available bandwidth, which can lead to distracting artefacts if measures aren’t taken at the production stage. In this article, we’ll discuss these challenges in more detail and describe several new tools that were designed specifi cally for re-purposing of audio over streaming services. The Balancing Act: Exciting Audio With Clear Dialog One of the biggest challenges with audio re-purposing. especially for podcasts. is to ensure dialog clarity while reducing the dynamic range of material that was originally mixed for. much more optimal sound environment, such as home radio/TV or. cinema. Programs with the highest dynamic range, i.e. the widest difference between the softest and loudest sounds, are consequently, some of the most diffi cult to repurpose. Since 60 | KITPLUS - THE TV-BAY MAGAZINE: ISSUE 99 MARCH 2015 most people don’t listen to podcasts in the quiet of their living rooms, ambient noise such as. passing subway train or. blaring siren require the listener to turn up the volume to hear the soft sections, which results in discomfort during the louder sections. And, as we’ve mentioned, the wide variation in the quality of playback equipment is. major factor in the overall quality of the listening experience. Podcast content with commercial breaks presents another layer of complexity. In one loudness normalisation method, an anchor element. most typically the human voice. is used as. loudness reference. However, for the most exciting mixes with the widest dynamic range,. variance exists between program loudness and the average level of voices. Depending on the balance of louder sections with average voice level in. mix, the average voice level can drop within the mix considerably after dynamic repurposing. Once again, the viewer reaches for the volume knob to make the spoken dialog more understandable. and interrupting commercials that have been correctly set to programmed loudness are now perceived as irritatingly loud. Until now, the best way to address these challenges has been to assign. mix engineer to remix the audio; i.e. manually go through the mix and turn the volume up for soft sounds and turn it down for louder sounds, however not only is this process expensive and time-consuming, it can be diffi cult to achieve. satisfactory result if the original audio stems are not available and traditional compression techniques are employed. Loudness Normalisation Goals for Podcasts One of the most important goals for content owners is to maintain control of loudness normalisation, because if they don’t do it, the OTT services will. Many steaming services now employ loudness normalisation techniques (for instance, Soundcheck for iTunes). If non-compliant audio is submitted to these services, the resulting processing can lead to transmission of audio that was not as originally imagined.