Decibel and Meters – VI

Loudness Manager or Loudness Engineer

In summary, controlling the loudness of a music program is fundamental not only to fit reenter in the normative terms of law (see broadcast and limits un live) but also to follow recommendations by performed studies and experiments guarantee at the time the best possible solution to get quality sound ( pleasant or not).
For the studio and mastering these two factors are essential to prepare various files and audio master depending on where they will be played (TV, radio, streaming, media, etc.), following the normative indications and recommendations seen in Figures 1 and 10 of the article Decibel and Meter IV.
In live though there is still no solid approach to this new technology, so I try to propose not only techniques of use LUFS Meter in live environment but also to furnish tips and indications for the emergence of new mixing methods and the birth of a new Professional figure, that of the Loudness Manager or Loudness Engineer, in some cases also covered by the figure of P.A Manger or System Engineer, As the approach follows and is part of the same family of calibration and management of the audio system (we will see in other arguments both the mixing techniques and the work of the P.A. Manager). These techniques can still be used in other work environments such as studio and mastering in order to achieve an improvement in the audio program.

The Loudness Manager goes then to complete the missing part in P.A. Manager, that is, the control and processing of the dynamic values of the audio signal output from the audio system, so far only made by ear to the sound engineer and thus comprised of so many limitations, as on everyone to fully exploit the dynamics of a sound in the range of SPL granted by today’s standards and exposure limits, but also as we will see (at your choice) to bring in a live event that sound to which the listener is accustomed.

Let’s focus on the work of the Loudness Manager:
It’s fundamentally important to have a high performance PC, a stand-alone software with LUFS Meter (not a plug-in in other software because it will not fully exploit the hardware and software’s potential, depending on the software’s capabilities Spins and the capability of the plugin type, e.g. vst, aax, etc., useful instead in the studio to understand the level of audio tracks already recorded).
To live audio recording and then use LUFS Meter Stand Alone.
You will need to have a quality sound card and always a measuring microphone of quality to interface with the software.

 

Calibrate LUFS Meter

The following indications refer to a mono or stereo audio program.

As for any other level meter, the LUFS Meter must be set so that for a 0 dBFS it corresponds to 0 dBTP so that to have optimal values as recommended.
Below is an illustrative table to calibrate LUFS Meter:

Fig. 1

CALIBRATE LUFS METER ( Live – Studio and Mastering )

LIVE

  1. Place a measuring microphone centrally on the axis of the PA LR audio system (example FOH station), or perform multichannel shooting techniques (useful in case of multiple amplification systems, e.g. delay tower, we will see these in other arguments), alternatively it is possible to pick up the split signal from the measurement microphones used to calibrate the audio system as the shooting methods are identical.
  2. Send the signal (via cable connection) from the measurement microphones to a multichannel audio interface connected to the computer where the LUFS analysis software is present. Set the LUFS software for signal picking from the microphones (it will be determined by setting the audio interface inputs to which the microphones are to be retrieved from the software).
  3. Send pink noise to the audio system (pre-calibrated, so that the frequency response is as straightforward as possible or optimized), adjust the audio volume level of the audio system to the maximum values (for Italy 95 dBLeqA – 102 DBmax).
  4. Adjust the signal level of the LUFS meter in the PC until it indicates a Peak or TP of 0 LUFS (it is important to analyze the Peak or TP level, not the RMS level, since it is the one that determines the maxium values before the Distortion).

 

    STUDIO – MASTERING

  1. Place a measuring microphone centered on the axis of the audio system or listening position (for each listening, such as Main Speakers, Near Field Speakers and any other listening system being present, whether stereo, mono or surround, it will be necessary to perform a calibration, since generally the central listening position is different as the positioning of these systems is different.) So, for ease of use and organization you always optimize LUFS Meter for the Main Speakers, then Near Field and then all the rest of the listeners.

n.b. If you do not recalibrate each time you listen, you can create calibration presets using the LUFS Meter settings so you can load the right one for your listening type.

2. Send the signal (via cable connection) from the measurement microphones to a multichannel audio interface connected to the computer where the LUFS analysis software is present.

3. Set the LUFS software for the signal picking from the microphones (it will be determined by setting the audio interface inputs to which the microphones are to be retrieved from the software).

n.b. It is recommended to use a separate PC, not the one used for recording / mastering, so that you can monitor and manage LUFS values independently and without too much stress on the recording machine and vice versa (use standalone plugins and not those internally enabled to the recording / mastering programs like vst, aax, etc …).

4. Send the noise to the sound system (pre-calibrated, so that the frequency response is as straightforward as possible or optimized), adjust the volume level of the audio system to the maximum values set for recording / mixing / mastering (eg 85 dBA, depending on the size of the studio).

5. Adjust the signal level of the LUFS meter in the PC until a Peak or TP of 0 LUFS is displayed (it is important to analyze the Peak or TP level, not the RMS level, as it is the one that determines the maximum values before the Distortion).

n.b.1 If the software has a gain control or offset, it is useful to adjust the gain of the microphone level by the software, so as to maintain the tonal quality of the microphone most intact possible.

n.b.2 For live environment is recommended calibration at each event, as there are different conditions that can lose its setting the measurement, as the continuous connection and disconnection of the audio equipment, use of different analog and digital cables, stage positioning, structures and different sound system. For the studio and mastering instead a recalibration every 30 to 60 days can be considered an excellent value, just to prevent any cable quality alterations and audio system. Always make the LUFS Meter rewrite in case of audio signal flow changes.

To complete the calibration process set levels of attention (maximum level dBTP, level LUFS, LRA) based on the type of audio program to analyze:

 

HOW TO DECIDE THE LEVEL OF AUDIO PROGRAM

For example, if we analyze a pop music of an artist who has an album or single recorded in the studio and marketed (possibly quality), it may be useful to make a pre-analysis through LUFS Meter or LUFS Level Checker (fig. 2) of the individual songs that will be performed during the live event or recording a new album / single (this is the best solution from the point of view of optimizing listening for the audience and the end user as it is generally used to hearing and listening the tracks through the media or files created in recording/mastering studio).

Fig. 2 2016-09-11_13-49-27.jpg

Another solution is to opt to consider the reference level by ITU (fig. 1 article Decibel Meter and IV), (this is an excellent solution if you mix in the studio recording / mastering techniques and poor production choices, so it is always good interface with the manufacturer in order to choose the best solution for loudness), (whether the factors identified in the recorded files are like those of recommendation the problem of choosing one method or the other is not persistent, it is in any case useful interfacing with the manufacturer for any variations).

N.B. It would be useful to study and create levels of more specific recommendations for each type of audio program.

Then, set via the options and settings LUFS Meter software with the limitations according to recommendations or reliefs, for example if during the analysis of a music program have characteristics like the one in figure 2 (on the left side analyzed the levels of the audio file, on the side right limits included for comparison) opt to set LUFS meter and / or even the meter of the pre-analysis (fig. 2) for any other reliefs, so as to have an optimum level comparison:

  • Limit dBTP (usually default) – 1 dBTP (if live), – 3 dBTP (if studio / mastering), possibly indicating red color setting dBTP.
  • Integrated LUFS – 9 LUFS (possibly with a different color than the dBTP and other scales).
  • If the meter allows, you set a minimum and maximum level of LUFS with its color for the LRA in order to always have an eye on LRA reference of the music program.

Some LUFS Meter allow to modify the timing of analysis Short Term and Momentary (recommended to keep the reference times of the standard EBU R-128, 3 s for the Short and 400 ms for the Momentary ). Sometimes it is also possible to modify and / or choose the type of Gate (also here leave set to G10 reference).

An example of a meter setting is shown below in Figure 3.

FIg. 3 2016-09-11_14-39-10.jpg

It is known as one goes to set the minimum loudness value to the level Integrated Loudness limit – 9 LUFS, and the maximum loudness value as (Integrated Loudness + LRA = – 9 + 5 (as it generally is not possible to enter values with a comma) = – 4 LUFS.

The resulting scale is shown below in figure 4.

Fig. 4 2016-09-11_14-39-27.jpg

It is noted the red peak value in the TP Meter by – 1 dBTP and the values ​​of loudness in LUFS Meter (from bluish – 4 LUFS and blue by – LUFS 9), – 9 LUFS the Integrated LUFS and the loudness range or by LRA – 9 LUFS a – 4 LUFS.

n.b.1 It ‘important to take note of the levels of each song in order to load them on LUFS Meter song after song, for convenience especially in live sound environment is possible in some of the preset meter program in order to change the type of preset according to run track (quick, fast, immediate), otherwise impossible to execute such operation in the live environment where the exchange rate between a song and another are often unpredictable.

n.b.2 Very often in a live situation we have no separate between a song and another, or different arrangements are made to tie two pieces or create a completely different, in this case it is useful experience and knowledge of songs by Loudness Manager in being able to decide when to end an analysis type and start with the other (can also be useful to optimize the loudness with an average of the tracks smoothly on).

Once the software is calibrated you can proceed to analyze the audio program.

Procedures of analysis and processing

For a proper analysis, it is necessary to place a measuring microphone in a centered position and in which all audio signals are supposed to arrive at a phase (e.g. close to the position of the sounder FOH) at a height of about 1.5 m to 1, 6m. We’ll see when we talk about P.A. Technical Positioning Manager for soundproofing and calibration of audio systems, microphone positions also suitable for Loudness relief, so it is true that you can use the same for both purpose and for the other.

The measuring microphone must then be interfaced with PC analysis software via audio interface (as straightforward and qualitative as possible).

Before you begin the analysis, you need to prepare your pc with analysis software so you have full monitoring. The two basic software to use are the one used to highlight the individual dynamic values of the tracks (if this has been performed and deemed necessary as seen before) (e.g., figure 2), so as to load from time to time the reference Analyzed (preset) or handwritten on the software and monitoring the audio signal taken from the microphone to immediately understand the difference between playback dynamics and the desired one. The other software is a real-time analysis software to detect the factors that we will list below.
The basic data to be collected and considered as shown in figure 2 are the TP Max, Integrated Level (or Program Loudness Level considered as a limit), LRA Max (or Loudness Range Amplitude).

For the peak value in the case of live event – 1 dBTP can be considered an optimal value, with 0 dBTP you are always at risk of clips of the analysis software. For a studio recording it is good to be around – 3 dBTP.

n.b. During the analysis it is possible that some peaks lead LUFS Meter to detect signal over the LUFS 0, + 1 LU for this is not a problem as it affects relatively on the extent and stability of the software and falls between the analysis tolerances, in addition it is recommended adjust (reduce) the signal level taken from LUFS Meter.
The Integrated Program Loudness LUFS or indicated in the recommendations ITU BS.1770 is an average value indicative, for live events swing of + \ – 1 dB is acceptable having regard to the variations of random dynamic that is at stake.
It’s important to analyze every single track independent of each other, at the end it is still possible to make a general calculation of the average value Integrated LUFS the duration of the event or the entire album.
To live simply off the analyzer when it finishes the song and turn it on when the other side or load the new preset (fig. 5 button x).

Fig. 5 2016-09-10_18-13-12.jpg

It is useful to exclude from the analysis any musical with spoken inputs and outputs (for example, the presentation of the track or a dedication or announcement at the end) that would reduce the average value detected by altering the measurement in accordance with the average loudness perceived by the human ear for that tune musical.

n.b. GATE settings should already take no breaks, but background noise (especially the public one) could alter its functionality, so it’s good in live contexts, use pauses manually, via button II in Figure 5.
Getting control loudness level (Integrated and LRA) is fundamentally important as many think it’s the Headroom (range that goes from the maximum rms value of the peak value) to give the dynamic perception of sound, but in Loudness Range is actually the same.
The more the range is wide and the more dynamic it will be perceived, the shoter it is and the more compression it receives, the more Integrated LUFS level is high and the volume will be perceived. Headroom control with peak dBTP peak value essentially is the function of limiting distortion phenomena and giving strength to the perceptivity of dynamics, thus helping the extension of dynamic perception, a sound with a small headroom can still have a high LRA .

This aspect also helps a lot of mixing techniques when you need to use dynamic compression or expansion to have a control LUFS for the Loudness value of the musical instrument or the mix to be processed can help you adjust more finely the processor parameters. It will be important to go to act within the LRA (example to compress can be useful to start from the highest point of the Loudness Range, in the above example – 4 LUFS, to expand the dynamic take the minimum point of the Range Loudness, as in the example first – 9 LUFS).

An alternative may be to act on the RMS signal peaks in order to give it a dynamic compression but lighter and transparent, this is possible by acting on the value of LUFS Momentary (analysis window in 400 ms).

The level of Headroom can be useful to calibrate Limiter in order to limit distortions.

Returning to the graph in figure 5 of Article Decibel Meter and III, it is possible to determine a scale of levels of a meter LUFS depending on the type of processor to be used.

Fig. 6 2016-09-12_10-14-22.jpg

It is also noted the presence of the Gate adjusted according to the noise level to be deleted.

During the processing of each musical instrument it is not necessary to try to get to as recommendation values ​​but you can outline the right tool dynamic instrument, during processing of a mix instead is fundamental recovery or dynamic growth as a whole as per the recommendation .
Not having reference values ​​then it can be complicated the analysis of the dynamics of from LUFS Meter instrument. In the studio having a recorded file is much easier, through an analysis program such as the one in figure 2 it is possible to analyze the recording and understand their values. In live instead everything happens in real time, unless you create a virtual mix with recordings of the tools in previous events. In the case of live in “direct” LUFS Meter as does Figure 4 can retain the maximum of the Short-Term window values ​​peaks (S) and Momentary (M), from these two values ​​it is possible to determine the maximum level for the compression (the level given by Momentary or some LUFS below to have a higher dynamic compression) and the minimum level for the expansion (the given level from the Short Term).

 

Dynamic Headroom

From LUFS Meter knowing the Loudness Range is possible to obtain the Dynamic Headroom (Momentary Headroom and Short Term Headroom), this helps to ensure a good protection against distortion while preserving the values ​​of loudness sought as per the recommendation.

n.b. For distortion from Headroom we do not only mean the audio distortion above 0 dBFS and distortion of the equipment but also the distortion of the image and presence due to the strong dynamic shocks in a short time which can have that particular sound. This is because even the most sophisticated audio waste equipment fails to transduce the original analog sound in a transparent manner but always induce acceleration phenomena or dynamic deceleration (even more so is fast and varies in the input dynamic range), which precisely alter these perceptual factors.

The Momentary dynamic Headroom can be considered the value that goes from Momentary Loudness to the peak value dBTP, the Short Term Headroom can be considered the value that goes from the Short Term Loudness to the peak value dBTP (fig. 7).

Fig. 7 2016-09-12_10-35-10.jpg

The Momentary Headroom is the most dangerous as it has the highest level and faster in bringing in audio distortion, equipment and perception, possibly by means of adjustable limiter.

The dynamic headroom to keep under control during the analysis, however, is the Integrated Headroom that represents the value that goes by the Integrated LUFS to peak value dBTP.

The Integrated Headroom helps not only to limit the distortions but also the dynamic perception and loudness of the sound data from the Integrated LUFS.

The optimum setting for the Integrated Headroom is the level of Loudness Range LRA.

A short LRA as will be more compressed sound having a generally Integrated LUFS high and a lower level of Headroom, so if the Integrated LUFS is high (values from recommendation are also optimized to allow a proper Integrated Hearoom) Integrated Headroom will be low and protected against distortions. Conversely, if LRA is high it will be a dynamic sound generally having a low and a high Integrated LUFS Headroom, so if the Integrated LUFS is low the Integrated Headroom will be high and will increase the distortion values.
It’s so important to try to maintain levels of recommendation and for those who experiment with new capabilities.

In case of mix already made it is good practice to keep the LRA level measured, in the example in figure 2 to maintain the headroom is 5 LRA.

 

Expansion and Compression

If Integrated LUFS value is too low compared to the limit set likely Momentary and Short Term and dBTP are all low and the instrument may be out of calibration, or you are trying to compare a low audio program loudness level with a recommendation that instead consider a higher generic media.

Useful then optimally calibrate the LUFS Meter as indicated in Figure 2 (if already recorded track) or as by recommendations ITU and possibly proceed to give gain for this type of audio program to bring the level to the optimum values ​​for the analysis, report then the gain level to the calibration level for the subsequent tracks and again consider the measured level. As a point of optimum gain is always considered the maximum dBTP value.

If the level of Integrated LUFS is too high will be necessary to expand the dynamic, if it is too low compress it, acting with the parameters of the processor considering how the threshold level of Integrated LUFS.

n.b. As Today many tools are emerging, mostly of software (plugin) that allow you to work directly covered on the loudness of the music program deciding the threshold level Integrated LUFS or LKFS (sometimes Momentary and Short Term, only Peak), the algorithm processes so in an automatic way the compression or expansion necessary bringing the signal level to that determined in the settings (fig. 8).

Fig. 8 2016-10-07_13-32-46.jpg

 

Graphics and Annotations

Many LUFS Meter allow you to extrapolate on external file the data collected during the analysis period, this can be useful for making comparisons and considerations on the data found in order to establish new methods of analysis, qualitative recommendations, compression methods and expansion in order to optimize the dynamic aspect of the audio signal, or for simple information purposes.

Very important aspect if present are the temporal trend graphs (fig. 9).

Fig. 9 2016-09-12_11-57-10.jpg

In the LUFS Meter different time windows are displayable (vertical plane, horizontal, simple graphic lines), each uses the most appropriate and with which is better for reading.

The aim is to eventually be able to define what caused an increase or decrease of the Integrated LUFS. In the graph in Figure 8, the signal sequence in time is defined by the analysis of the Short Term window and Momentary, While the horizontal continuous line is the value of the Integrated LUFS. The LUFS line is constant over time and always defines the current value (it would have been better also in this case the trend over time of the Integrated level LUFS).

From about 28 seconds to 20 seconds, and then for a period of analysis of 8 seconds, there is a marked increase of the signal level, in this case listening to the song and following the chart has been highlighted that the entry of a vocal part has It constituted a decided increase in the Integrated LUFS, knowing what is possible to act, for example, by attenuating the entry if it is too high or use a compressor in order to limit the excursion of Dynamic Headroom. So instead of doing work with the entire mix to bring the Integrated LUFS signal at optimum levels on the individual working tool (often the variation of the Integrated LUFS is given by a single tool rather than from the whole mix), more complex method is to be view that to manage, but qualitatively better.

 

Conclusions

The loudness managing techniques not only can have outlets in a live environment, but can also define new standards of measurement in the specifications of loudspeakers and audio speaker for the relief of Range and Headroom Loudness.

 

More on Decibel and Meter:

Decibel and Meter – I ( Decibel and Standard Types )

Decibel and Meter – II ( Analog Meters )

Decibel and Meter – III ( Digital Meters and Software )

Decibel and Meter – IV ( Normalization and LUFS Meter )

Decibel and Meter – V ( Meters in Audio Equipment )

 

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