I read an interesting post on the DIGI site and thought i'd post this for reference.
The TASA Standard
Recommendations from the TASA Ad Hoc Committee
for regulating motion picture trailer audio volume.
With the advent of stereo and multi-channel digital trailers, loud
trailer sound became the number one complaint in movie theatres.
Trailers were far louder than the features they preceded, and theatres
compensated by turning down the volume of the trailers and thus features.
To solve this problem, the TASA AD HOC COMMITTEE created a
STANDARD for trailer volume to rectify the situation. It should be
noted that the TASA Committee believes the complexity of the problem
is such that any “Solution” must be tried and proven in the field; the
procedures may be imperfect at first due to the complexity of the
problem. The actual “number” or “upper volume limit” may be adjusted
periodically as experience in the field demands.
Since the original implementation of the TASA Standard in 1999,
the measurement procedures described herein have been adopted as an
The standard is divided into five sections and an annex:
1) MEASURING TECHNIQUES. This section defines in
engineering terms the techniques used to quantify trailer volume
into useful units of measurement.
2) THE NUMERICAL UPPER LIMIT. This is the actual
“number” or upper volume limit that trailers should not exceed
using the measuring techniques set forth in section 1.
3) THE TASA CERTIFICATE. This section outlines the
modus operandi for independent audio engineering firms to
“certify” trailers that satisfy the TASA Standard.
4) INDEPENDENT AUDIO ENGINEERING COMPANY
QUALIFICATIONS. This section details the qualifications
that independent audio engineering companies must have in
order to issue TASA Certificates.
5) POST RELEASE BLIND PRINT CHECKING. This
section outlines the recommended procedures for blind field
checks to insure compliance by all parties participating in the
INFORMATIVE ANNEX: DUB STAGE AND OPTICAL
CAMERA RECOMMENDED PRACTICES. This section
details the recommended procedures to be followed at the dub
stages and at the optical camera.
PART ONE: MEASURING TECHNIQUES
Recommended Practice: Method of Measurement for Equivalent
Perceptual Loudness of Motion Picture Soundtracks.
“The Method of Measurement for Equivalent Perceptual Loudness of
Motion Picture Soundtracks” is a system for producing a NUMBER that
relates to the perceptual loudness of motion picture soundtracks. The
number produced can be used to quantify and regulate the maximum
audio volume of motion picture trailers.
DFFS: Distribution Format Sound System.
Frequency weighting equalizer: a device having a frequency response
that makes the system correspond with perceived loudness, roughly
accounting for the frequency response of human hearing.
Frequency response: the amplitude response of a system as a function
of input frequency, usually rated in decibels over a frequency range.
Pink noise: random, stochastic signal having a continuous spectrum with
equal energy per equal logarithmic intervals of frequency, and with
Gaussian probability distribution of instantaneous amplitude.
Sound Equivalent Level: the average amplitude of sound measured
over an interval of time, calculated according to the equation in section
Trailers: previews of coming attractions presented prior to a feature
film in a motion picture theatre.
Relative and Absolute Sound Pressure Levels for Motion Picture Multichannel
Sound Systems – SMPTE Recommended Practice – RP200 – A12
.004 – 1690
“Are Movies too Loud?” – Ioan Allen, SMPTE Journal (March 22nd
British Standard BS 5550 7.4.2:2000 Specification for maximum
recording levels for commercials and trailers.
ISO 21727 Cinematography – Method of measurement of perceived
loudness of motion-picture audio material.
1.4 METHOD OF MEASUREMENT
The method of measurement shall be as described by the block diagram
given below, with an Input Calibration section, a Frequency Weighting
Equalizer to better correspond to human hearing response than unweighted
measurements, a Sound Equivalent Level section for assessing
the cumulative effect of the energy of the sound level over the time
interval of the program, and a Meter Indicator. The elements of the block
diagram are further defined in sections 1.4.1 – 1.4.4. The measurement
interval, and the accuracy and precision of measurements are given in
sections 1.4.5 – 1.4.6.
Other methods of measurement are permissible so long as the results are
equivalent to those specified herein within the required accuracy of
Block Diagram of Method of Measurement
1.4.1 INPUT CALIBRATION
The input calibration section shall scale an input voltage, defined for each
of the Distribution Format Sound Systems (DFSS), to a voltage that
corresponds to a reference Sound Pressure Level. Each DFSS shall
provide calibration information and test materials, such as test films or
discs, to Independent Audio Engineering Companies in order to make
possible independent verification of soundtrack level on any trailer.
For example, using SMPTE Standards, 20 dBFS on a digital
medium represents the reference level. A DFSS may produce
4 dBu at 20 dBFS, and may be designed so that such an
electrical reference level produces 85 dBC Sound Pressure Level
re: 20 Pa for each channel.
For multi-channel sound, each of the source channels shall be electrically
summed in the correct proportion to the Sound Pressure Level calibration
of the individual channels. For example, if the surround level is
calibrated at 82 dBC for each channel rather than 85 dB given in the
example above, the contribution of each surround channel to the sum
shall be 3 dB less than a screen channel.
To prevent differences between electrical addition (vector) and acoustical
addition in the reverberant field of a room (scalar), each of the channels
shall employ a separate detector circuit, and the output of each of the
detector circuits shall be added.
1.4.2 FREQUENCY RESPONSE AND TOLERANCE OF
FREQUENCY WEIGHTING EQUALIZER
The frequency weighting equalizer is based on an International
Telecommunications Union recommended filter for the assessment of
background noise in audio programs. This filter (more accurately,
equalizer) has also been found to be useful for the purpose of assessing
the human response to the loudness of soundtracks. The frequency
response of the equalizer, and the tolerance on the response, is given in
the following table:
Frequency in Hz Response in dB Tolerance in dB
31 -35.5 + 2.0
63 -29.5 + 1.4
100 -25.4 + 1.0
200 -19.4 + 0.85
400 -13.4 + 0.7
800 -7.5 + 0.55
1000 -5.6 + 0.5
2000 0.0 + 0.5
3150 3.4 + 0.5
4000 4.9 + 0.5
5000 6.1 + 0.5
6300 6.6 + 0.0
7100 6.4 + 0.2
8000 5.8 + 0.4
9000 4.5 + 0.6
10000 2.5 + 0.8
12500 -5.6 + 1.2
14000 -10.9 + 1.4
16000 -17.3 + 1.65
20000 -27.8 + 2.0
31500 -48.3 + 2.8, - ∞
Note that for the purposes of insertion gain, the frequency 2.0 kHz is used
for the 0 dB reference level. For the purposes of tolerance, the insertion
gain is to be adjusted at the reference frequency of 6.3 kHz to 6.6 dB,
since this is the center frequency of the boost in the equalizer. If a 1 kHz
reference frequency is used, levels shall be offset by 5.6 dB, as shown in
1.4.3 SOUND EQUIVALENT LEVEL
1.4.4 METER INDICATION
The meter indication shall be the result of the frequency weighting
equalizer and the sound equivalent level circuit, with scaling to represent
the acoustical Sound Pressure Level which the program material would
produce when playing the test material specified in the next paragraph at
the Standard Fader Setting over a sound system calibrated to the standard
of the DFSS in use.
The frequency response of theatrical sound systems, the B-chain
response, specified in SMPTE 202, is deliberately not to be accounted for
in this method of measurement. The X curve response is not to be a part
of the frequency weighting equalizer.
Note: Acoustical rather than electrical summation of the channels,
and the fact that the X curve is not accounted for in the electrical
measurement described herein, will probably make the electrical
based measurement described in this method of measurement
different from the reading of a Sound Level Meter - even if one
were to be equipped with the frequency equalizer specified herein
and made to measure Leq M. In addition, variations from room to
room, including seat location selection, would make Sound Level
Meter measurements unreliable.
1.4.5 MEASUREMENT INTERVAL
The length of the measurement in time shall correspond + 3 seconds to
the length of the audio program material. In practice, the start button of
the measuring device shall be pushed within 3 seconds of the first audio
heard by the audience. The stop button shall be pushed within 3 seconds
of the final audio heard by the audience. The measurement does not stop
during any silences within the body of the trailer. The measurement does
not start with the academy leader, the green card or any other visual or
footage reference; the only section to be measured for this standard is the
section between the 1st audio heard, plus or minus 3 seconds, and the
final audio heard, plus or minus 3 seconds.
Any material measured using these procedures with a duration of 30
seconds or less shall be measured to within + 1 second of the length of
the program. In other words, the start button of the measuring device shall
be pushed within 1 second of the first audio, and the stop button shall be
pushed within 1 second of the final audio.
1.4.6 ACCURACY AND PRECISION OF MEASUREMENT
Independent Audio Engineering Companies that measure trailers to check
for TASA compliance (See Parts 3 and 4), shall maintain the accuracy of
the measurement procedure to within + 0.3 dB. This tolerance on
accuracy shall include a summation of all sources of error, including, but
not limited to: input calibration error, insertion gain, error in the
frequency weighting filter or elsewhere, calculation of the sound
equivalent level, and meter indication. Independent Audio Engineering
Companies shall not be responsible for the accuracy errors that occur due
to calibration error on the part of the Distribution Format Sound Systems,
which shall be maintained by the manufacturers of the various sound
systems, including variations due to hardware and software upgrades.
The precision considered in a pass/fail response shall be to the nearest 1
dB. The Independent Audio Engineering Companies may maintain
internal records to greater precision.
PART TWO: THE NUMERICAL UPPER
2.1 A FLEXIBLE NUMBER
Any volume standard for trailers must take into account feature volume as
well as playback habits of theatres in order to be effective. Establishing a
standard will have an element of trial and error in the field, and may not
be achievable in a single precipitous drop in trailer volume. It may be
prudent to take several conservative drops in volume over the course of
several months in order to reach a desirable level without accidentally
“overshooting” and making the trailers too low. To this end, the TASA
Ad Hoc Committee meets periodically to determine whether or not the
standard requires revision.
PART THREE: THE TASA CERTIFICATE
3.1 “COMPLIANCE” REQUIRES A TASA CERTIFICATE
The upper volume limit established by TASA can be adhered to on the
dub stage and on the optical track negative, (or other theatrical release
medium), but full TASA compliance requires that an “Independent Audio
Engineering Company” (an “I.A.E.”) measure either a composite print or
a soundtrack-only print of the trailer, using the measuring techniques and
upper limit guidelines established in Parts 1 and 2 of the TASA Standard.
If the mix passes the TASA Standard, the Independent Audio Engineering
Company will issue a “TASA Certificate of Compliance”. Only when the
I.A.E. has issued the TASA Certificate will the trailer have satisfied the
3.2 I.A.E. CERTIFICATION
Independent Audio Engineering Companies who wish to issue TASA
Certificates must apply for Certification by the TASA Committee.
Applications should be submitted in writing to the chairperson of the
TASA Committee for consideration by the full committee.
3.3 I.A.E. DECERTIFICATION
Independent Audio Engineering Companies can be decertified at any time
by the TASA Committee for engineering or administrative failures.
3.4 METER CALIBRATION GRACE
If a trailer fails to pass the TASA Standard at an I.A.E. and the certifying
engineer discovers that unintentional Leq M meter mis-calibration on the
dub stage was to blame, the certifying engineer may still issue a TASA
Certificate. No further certificates may be issued for trailers mixed on
that dub stage until the meter is recalibrated.
3.5 TASA CERTIFICATE INFORMATION
The TASA Certificate must include: the name of the I.A.E., the name of
the trailer certified, the name of the studio, the date mixed, the dub stage,
the Leq M number measured, the name and signature of the certifying
engineer, and any other pertinent information.
PART FOUR: INDEPENDENT AUDIO
In order to be certified by the TASA Committee, any Independent Audio
Engineering Company must meet the following standards:
4.1 The trailer volume measuring work must be performed by, or under
the direct management and responsibility of either:
a) a registered Professional Engineer with a current license from
the State of California, or
b) a recognized audio expert, with recognition consisting of Fellow
grade membership in the Audio Engineering Society, the British
Kinematograph Sound and Television Society, the Institute of
Electrical and Electronics Engineers, or the Society of Motion
Picture and Television Engineers, or
c) any engineer who demonstrates to the TASA Technical
Committee proficiency in the measuring techniques described in
4.2 The I.A.E. shall maintain primary standards for rms ac voltage and
thus equivalent Sound Pressure Level reference traceable to the National
Institute for Standards and Technology. The I.A.E. must maintain the
necessary test equipment to qualify the frequency response of the
equalization network, and tone burst generators as required to qualify the
time response of the sound equivalent level measurement to within the
requirements of the section “Accuracy and Precision of Measurement”.
The I.A.E. shall be responsible for the calibration of its own equipment,
and for maintaining the accuracy of measurement described in the
4.3 The I.A.E. shall not be owned in whole or in part by any entity that
produces, distributes, or exhibits motion pictures or associated trailers
intended for theatrical exhibition. An exception to this rule can be made
if the Independent Audio Engineering Company excludes itself from
measuring the related company’s product; i.e. if the company is owned by
a parent company that produces films on occasion, the I.A.E. must
exclude itself from certifying the parent company’s product. The I.A.E.
in these circumstances must make its equipment and personnel available
to be supervised (at the I.A.E.’s expense) by an engineer approved by the
4.4 The I.A.E. shall not be owned in whole or in part by any entity that
manufactures or distributes a Distribution Format Sound System.
4.5 The I.A.E. shall not be owned in whole or in part by any entity that
edits, mixes, or otherwise makes trailers for theatrical feature films. The
same exception can be made for this rule as the one for 4.3: The I.A.E.
cannot certify product that it or its related company has worked on unless
supervised by an engineer approved by the TASA Committee.
4.6 The I.A.E. shall not be owned in whole or in part by any entity that
produces soundtrack negatives or prints for trailers for theatrical feature
PART FIVE: POST RELEASE BLIND PRINT
5.1 The TASA Committee recommends that any studio or entity
adopting the TASA STANDARD will in so adopting, be giving the
certifying I.A.E. implicit and unconditional permission to pull one print of
each trailer at random (from the lab or depot of the studio’s choice) for a
blind volume check. The I.A.E. will double check the audio volume
using the engineering standards set forth in section 1. This will serve to
insure full compliance by all parties.
5.2 An I.A.E. performing a post release check on a trailer may issue a
notice of TASA noncompliance if the trailer print fails the Standard.
5.2.1 An I.A.E. may also issue a notice of noncompliance if a studio
does not make a randomly pulled blind check print available.
5.3 The I.A.E. will forward a copy of the notice of noncompliance to
the chair of the TASA Committee, to the studio that released the trailer,
and to any other entities that adopt the TASA Standard.
INFORMATIVE ANNEX: DUB STAGE AND
OPTICAL CAMERA RECOMMENDED
6.1 Trailers shall be mixed at volume levels that are comfortable to the
ear on the dub stage. Care should be taken on dialog levels in particular,
such that they do not exceed normal feature film levels.
6.2 Upon completion of a trailer mix, the mixer shall measure the
Leq M . If the resultant number exceeds the recommended upper limit in
effect at the time of the mix, the mixer shall remix the trailer to lower the
volume until it meets the upper limit or falls below. If the Leq M number
is below the upper limit, the mixer shall not raise the volume of the mix
solely to meet the upper limit since this would likely result in painfully
loud dialog levels.
6.3 Upon completion of the mix, the mixer shall note the Leq M number
into a log to be kept on the dub stage. In addition, the mixer shall fill out
a dub stage report which lists the trailer mixed, the dub stage, and the
Leq M number measured on the stage. This dub stage report shall be
forwarded with a trailer soundtrack-only print, composite print, or other
digital audio delivery medium to the I.A.E. for final TASA certification.
The reason for the dub stage report is to help the I.A.E. check the
calibration on the dub stages. If every mix that gets checked by an I.A.E.
comes with a report, then every mix will help confirm that the Leq M
meters are in calibration. This will prevent out- of-calibration meters
from being discovered only when a mix fails the TASA Standard.
6.4 Under no circumstance should studios bracket tracks at the optical
camera. All sound decisions must be made on the dub stage with the
guidance of the sound mixer.
The TASA Ad Hoc Committee is comprised of marketing post production
representatives from all of the studios, as well as engineers from the
digital sound companies, mixers, and independent audio experts. The
TASA Committee does not endorse any one company’s product or
services. All TASA volume recommendations are recommendations
only. The TASA Committee believes the method of measurement
described herein is the best available at the time of this writing. If and
when better volume assessment techniques are developed, the TASA
Committee may amend the TASA Standard. Any outside agencies that
endorse or adopt the TASA Standard may make these recommendations
mandatory at their own discretion.