Buying Guide・2015-10-21

[Acoustics] Discussing the Need for Dynamic Compression in PA Microphones from the Perspective of Loudness

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【Written by / Hunk Huang】

In this issue, we will discuss the topic of dynamic processing in public address systems. Why do we need to discuss this? Because the usable dynamic range in a public address system is limited. Its lower limit is the ambient background noise, and its upper limit is determined by sensitivity and allocated power, minus the distance to the listener's ears. How much is left? Actually, it is only about 20 to 30 dB. Moreover, since public address is meant for continuous listening, broadcasting at high sound pressure levels is not permitted. Therefore, how to make the best use of the dynamic range has become a crucial question to consider.

In the recording industry, there is a term called the "Loudness War," which originated in the pop music industry with the desire to broadcast songs at the maximum volume on the "user end" to attract listeners' attention. Consequently, the recording industry broke traditional norms, utilizing the headroom above 0 dBu and packing it as much as possible. By compressing the original signal—"compressing large signals and raising the overall signal"—the music sounds very loud on the radio and in TV music videos. This catches the ears of listeners and draws eyes to the idol, facilitating subsequent endorsements and marketing.