A common experience among millions of viewers: you are watching your favorite series at a comfortable volume when an advertising block bursts in, forcing you to rush headlong towards the remote control. This calculated shock could have its days numbered in Spain thanks to quantifiable technical criteria to monitor the sound level of advertisements.
The law. The National Markets and Competition Commission has established for the first time a series of criteria so that the sound level of the advertising blocks does not exceed that of the programs, according to the agreement INF/DTSA/083/25 published on November 20, 2025. The regulations extend the regulation that from summer 2025 DTT governs the entire audiovisual ecosystem: video streaming platforms such as YouTube and on-demand services, music applications such as Spotify, pay television and conventional and digital radio stations.
The regulator warns that non-compliance constitutes a minor infraction with penalties that can reach 200,000 euros in serious cases.
The technical deception: dB vs. LUFS. The advertising industry has for decades exploited a fissure in the traditional measurement of sound. Conventional decibels record the electrical amplitude of the signal, but ignore a crucial factor: how the human brain processes that sound information. Two recordings may register identical values on a traditional peak meter, and yet one is perceived as noticeably louder than the other.
The secret is in the frequency composition. Our auditory system responds unevenly depending on the pitch: mid frequencies (especially between 1 and 4 kHz, where the human voice is concentrated) are much more audible to us than deep bass or extreme treble. This physiological characteristic allows advertisers to create messages that sound louder without violating technical decibel limits.
The birth of the LUFS. The solution came when the International Telecommunication Union published the ITU-R BS.1770 standardadopted in August 2010 by the European Broadcasting Union. This system introduces the LUFS (Loudness Units relative to Full Scale), which integrate a weighting filter K that mathematically replicates the sensitivity of the ear. The result: a measurement that reflects actual perception, not just electrical power.
Spain aligns itself with Europe. He Royal Decree 250/2025approved in March, established for the first time an objective parameter for Spanish DTT: -23.0 LUFS with a tolerance of ±1.0 LU (Loudness Unit). This figure is not arbitrary, but coincides exactly with the normalized value that the European Broadcasting Union has been recommending since 2010. The CNMC has now taken the next step and has extended these criteria beyond traditional television.
Implementation. The Spanish regulator has opted for a gradual approach. The CNMC does not require platforms to reencode millions of hours of historical content immediately. The document allows operators to adopt “technical criteria that offer an equivalent level of protection”, a flexible formula that recognizes the characteristics of each medium. But implementation faces complex obstacles.
While traditional television networks control every second of broadcast from a production room, the streaming It works with distributed architectures where advertising is dynamically inserted through programmatic systems. YouTube, for example, hosts content generated by millions of users with disparate equipment, from professional studios to smartphones. Technically monitoring each ad inserted in real time in this tangle becomes a considerable logistical challenge.
Photo of Vadim Babenko in Unsplash / Elyas Pasban in Unsplash
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