What is TASA?
Why is TASA necessary?
TASA and the MPA:
What you need to know!
The TASA process for trailer finishers.
The TASA process for Digital Cinema trailers.
TASA Certified Independent Audio Engineering Firms.
What is "Leqm"?
Where do I get a Leqm meter?
How effective is TASA?
Who do I talk to at the MPA about trailers?
What about commercials in theatres?
Who are we?
TASA History.
The TASA Standard - Technical Document.

What is Leqm?

The TASA Standard quantifies trailer volume with a number that is derived using a measurement technique called: Leqm.

Leqm defines trailer volume as a decibel average over time, using a specific filter that emphasizes the mid and upper-range sound frequencies. The mid-range frequencies are those that are the most annoying to an audience. Examples include: breaking glass, shrill voices, and fingernails on a chalkboard! The filter characteristic is defined in the TASA Standard.

Mid-range and upper-range frequencies are not the only parameter that might result in a high Leqm reading. Since the Leqm measurement is integrated over the entire length of the trailer, a densely paced trailer with high volume throughout will have a higher Leqm number than a slower paced trailer with more quiet spaces in between the high volume sections. To illustrate, imagine that there are two trailers that are both at the upper volume limit. Neither can be raised without exceeding the TASA Standard. One trailer has relatively high energy, high volume music throughout. The other has lower music, but more variation between the loud and soft areas. The more dynamic trailer can have louder peak volumes than the trailer that has a more compressed range. In other words, the trailer with more quiet spaces can have louder explosions and still comply with the TASA Standard. The trailer that tries to be loud throughout, however, must be relatively lower in volume, and have lower peaks, to pass. Also, because Leqm emphasizes mid-range frequencies that are more irritating to the audience, the trailer that derives its volume from lower frequency bass sounds can be "louder" than the trailer that derives its volume from mid-range sounds.