https://www.nps.gov/grca/learn/news/2011-04-22_over-edge.htm

https://www.nps.gov/grca/learn/news/2011-04-29_fatality.htm

A woman who suffered fatal injuries in a fall in Grand Canyon National Park on Thursday, April 28, has been identified. https://www.nps.gov/grca/learn/news/2011-05-03_fatality.htm

At approximately 10:45 a.m. today, rangers retrieved the body of a young male from below the South Rim of Grand Canyon National Park. https://www.nps.gov/grca/learn/news/2011-05-06_retrieval.htm

In spite of the rapid response time, park emergency responders were not able to revive 72-year old John Debelack of Saddlebrooke, Arizona. https://www.nps.gov/grca/learn/news/2011-06-29_death.htm

At approximately 2:00 this afternoon, the Grand Canyon Regional Communications Center received a call from a park visitor reporting a man over the edge below Lookout Studio on the South Rim of Grand Canyon National Park. https://www.nps.gov/grca/learn/news/park-rangers-recovering-body-from-below-the-rim-at-grand-canyon-national-park.htm

At approximately 11:15 a.m. on Wednesday, August 31, the Grand Canyon Regional Communications Center began receiving reports of a vehicle hitting a rock wall on the canyon rim between Thunderbird and Kachina Lodges in Grand Canyon National Park. https://www.nps.gov/grca/learn/news/2011-08-31_car-v-wall.htm

https://www.nps.gov/grca/learn/news/2011-10-03_nr-fatality.htm

https://www.nps.gov/grca/learn/news/2011-10-27_range.htm

On Wednesday, October 26, Grand Canyon National Park Supervisory Park Ranger Lisa Hendy was awarded the National Park Service's 2011 Harry Yount National Park Ranger Award for excellence in the field of rangering. https://www.nps.gov/grca/learn/news/2011-10-27_hendy.htm

https://www.nps.gov/grca/learn/news/2012-02-27_fall.htm

Rangers in Grand Canyon National Park are seeking the public’s assistance in locating 47-year old Shaw Joseph Ostermann of Tempe, Arizona. https://www.nps.gov/grca/learn/news/2012-04-17_missing.htm

https://www.nps.gov/grca/learn/news/2012-04-27_recovery.htm

https://www.nps.gov/grca/learn/news/2012-04-27_boey.htm

https://www.nps.gov/grca/learn/news/2012-05-02_ident.htm

At approximately, 1:20 p.m. on Thursday, July 19, the Grand Canyon Regional Communications Center received a report that an older woman had fallen over the edge at Grandview Point, located on the South Rim of Grand Canyon National Park, and that she was not responding to people calling down to her. https://www.nps.gov/grca/learn/news/2012-07-19_over-edge.htm

On Friday, August 31, after approximately four weeks of investigation, Grand Canyon National Park rangers arrested 42-year old Brian Thompson of Cottonwood, Arizona, for conducting commercial operations in a national park without a permit. https://www.nps.gov/grca/learn/news/2012-09-21_arrest.htm

https://www.nps.gov/grca/learn/news/2012-12-10_body.htm

https://www.nps.gov/grca/learn/news/2013-01-14_search.htm

Twenty-one year old Kaitlin Kenney of Englewood, Colorado remains missing in Grand Canyon National Park; and an extensive search by the National Park Service has turned up no additional clues as to her whereabouts. https://www.nps.gov/grca/learn/news/2013-01-15_search.htm

Last night, the National Park Service and the National Park Foundation presented Grand Canyon's Chief of Emergency Services Brandon Torres with the 2012 Harry Yount National Park Ranger Award. https://www.nps.gov/grca/learn/news/2013-02-22_yount.htm

https://www.nps.gov/grca/learn/news/2013-03-05_recovery.htm

https://www.nps.gov/grca/learn/news/2013-03-22_recovery.htm

Twenty-one year old Drake L. Kramer remains missing at Grand Canyon National Park; and a six day search by the National Park Service has turned up no additional clues as to his whereabouts. https://www.nps.gov/grca/learn/news/kramer-limited.htm

On Monday, May 11th the Grand Canyon Regional Communications Center was contacted by the Tallmadge, OH Police Department reporting a missing man who was believed to be suicidal and currently at Grand Canyon. https://www.nps.gov/grca/learn/news/intervene.htm

On May 20th, a private boating trip reported the wreckage of an airplane to park rangers at Diamond Creek. https://www.nps.gov/grca/learn/news/park-rangers-respond-to-report-of-plane-wreckage.htm

A National Park Service search mission continues in efforts to find Morgan Heimer. https://www.nps.gov/grca/learn/news/rangers-search-for-missing-river-guide.htm

On Monday, June 27 at approximately 4:45 pm, the Grand Canyon Regional Communications Center received a call reporting a visitor over the edge at Mather Point. https://www.nps.gov/grca/learn/news/mather-point-over-the-edge.htm

At approximately 9 am on Thursday, December 1, the Grand Canyon Regional Communications Center received a call alerting rangers to a potentially suicidal individual at Grand Canyon National Park. https://www.nps.gov/grca/learn/news/potential-suicide-grand-canyon.htm

At approximately 12:30 am on December 12, the Grand Canyon Regional Communications Center received a call alerting rangers to an overdue individual at Grand Canyon National Park. https://www.nps.gov/grca/learn/news/possible-suicide-twin-overlooks.htm

At approximately 5 pm on Saturday, January 28, the Grand Canyon Regional Communications Center received a call reporting a man who had fallen from the rim near the South Kaibab trailhead. https://www.nps.gov/grca/learn/news/fall-south-kaibab-trailhead.htm

On Tuesday, March 14, at 4:17 pm, the Grand Canyon Regional Communications Center received a call reporting that a visitor had fallen from the rim of the canyon west of Mather Point. https://www.nps.gov/grca/learn/news/mather-point-fatality.htm

At approximately noon on Sunday, May 21, the Grand Canyon Regional Communications Center received a call about a single car accident on Center Road in Grand Canyon Village. https://www.nps.gov/grca/learn/news/motor-vehicle-accident.htm

On Tuesday, June 13 at approximately 7:45 pm, the Grand Canyon Regional Communications Center received a call reporting an overdue hiker. https://www.nps.gov/grca/learn/news/missing-hiker-grand-canyon.htm

The National Park Service reminds visitors to enjoy Grand Canyon safely and to remember a visit to Grand Canyon is not like going to the zoo-there are no fences to separate you from real wild animals. https://www.nps.gov/grca/learn/news/view-wildlife-safely-2018-1.htm

Visitors to Grand Canyon, especially inner canyon hikers, mule riders, and backpackers, need to prepare for excessively hot days in the coming weeks. https://www.nps.gov/grca/learn/news/hike-smart-reminder.htm

National Park Rangers at Grand Canyon National Park are strongly urging visitors to Grand Canyon, especially inner canyon hikers, mule riders, and backpackers to be prepared for excessively hot days in the coming weeks. https://www.nps.gov/grca/learn/news/hike-smart-at-grand-canyon-national-park.htm

At approximately 1:00 am this morning, October 11, an officer involved shooting occurred on the South Rim of Grand Canyon National Park. The suspect is in custody at this time. The National Park Service (NPS) does not believe there to be any ongoing safety concerns for the public. The park remains open and all visitor services are available. https://www.nps.gov/grca/learn/news/ranger-involved-incident-under-investigation-at-grand-canyon-national-park.htm

Elyssa Shalla, park ranger at Grand Canyon National Park, has been selected as a recipient of the Intermountain Region 2018 Freeman Tilden Award. https://www.nps.gov/grca/learn/news/elyssa-shall-regional-award.htm

Old-growth forests provide unique habitat features and landscape functions compared to younger stands. The goals of many forest management plans in the Pacific Northwest include increasing the area of late-successional and old-growth forests.

Soil disturbance is a visually apparent result of using heavy equipment to harvest trees. Subsequent consequences for growth of remaining trees, however, are variable and seldom quantified. We measured tree growth 7 and 11 years after thinning of trees in four stands of coast Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb. Franco)) where soil disturbance was limited by using planned skid trails, usually on dry soils. The three younger stands had responded to nitrogen fertilizer in the 4 years before thinning, but only one stand showed continued response in the subsequent 7- or 11-year period after thinning. The most consistent pattern observed was greater growth of residual trees located next to skid trails. The older stand also showed greater growth in trees located next to skid trails, whereas tillage of skid trails failed to benefit growth of nearby residual trees for the first 7 years after tillage. We conclude that traffic that compacted soil only on one side of residual trees did not reduce growth of nearby trees.

Mule deer populations in central Oregon are in decline, largely because of habitat loss. Several factors are likely contributors. Encroaching juniper and invasive cheatgrass are replacing deer forage with high nutritional value, such as bitterbrush and sagebrush. Fire suppression and reduced timber harvests mean fewer acres of early successional forest, which also offer forage opportunities. Human development, including homes and roads, is another factor. It is this one that scientists with the Pacific Northwest Research Station and their collaborators investigated in a recent study.

We monitored coarse woody debris dynamics and natural tree regeneration over a 14-year period after the 1991 Warner Creek Fire, a 3631-ha (8,972-ac) mixed severity fire in the western Cascade Range of Oregon. Rates for tree mortality in the fire, postfire mortality, snag fall, and snag fragmentation all showed distinct patterns by tree diameter and species, with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) more likely to survive a fire, and to remain standing as a snag, than other common tree species. Natural seedling regeneration was abundant, rapid, and highly variable in space. Densities of seedlings >10 cm height at 14 years postfire ranged from 1,530 to 392,000 per ha. Seedling establishment was not concentrated in a single year, and did not appear to be limited by the abundant growth of shrubs. The simultaneous processes of mortality, snag fall, and tree regeneration increased the variety of many measures of forest structure. The singular event of the fire has increased the structural diversity of the landscape.

This report addresses the need for developing consistent regional guidelines for stand-level management that integrates goals and objectives for dry forest restoration and habitat management for the northern spotted owl.

Rangeland exclosures installed primarily in the 1960s, but with some from the 1940s, were resampled for changes in plant community structure and composition periodically from 1977 to 2004 on the Malheur, Umatilla, and Wallowa-Whitman National Forests in northeastern Oregon. They allow one to compare vegetation with all-ungulate exclusion (known historically as game exclosures), all-livestock exclusion (known historically as stock exclosures), and with no exclusion (known as open areas). Thirteen upland rangeland exclosures in northeastern Oregon were selected and are presented with plant community trend data and possible causes of changes over time. Key findings are that moderate grazing by native ungulates afforded by the livestock exclosures generally stimulated bunchgrasses to retain dominance and vitality; native bunchgrasses can replace invasive rhizomatous plants given a reduction in disturbance over time; shrubs increased without ungulate use in shrubland communities; and invasive annuals that established following severe disturbances to the grassland community diminished with aggressive competition from perennial bunchgrasses.

In July 2006, more than 170 researchers and managers from the United States, Canada, and Mexico convened in Boulder, Colorado, to discuss the state of the science in environmental threat assessment. This two-volume general technical report compiles peer-reviewed papers that were among those presented during the 3-day conference. Papers are organized by four broad topical sections—Land, Air and Water, Fire, and Pests/Biota—and are divided into syntheses and case studies.

Robertson has been accused of making "baseless, damaging and self-serving attacks"

The Daily Record columnist claims it's a deflection from the club's failures on the pitch this season

160 photos of the strange and intriguing objects people display behind their windows, for passers-by to look at. These things...

If listeners find themselves using the volume up and down buttons a lot, level differences within your podcast or audio file are too big.
In this article, we are discussing why audio dynamic range processing (or leveling) is more important than loudness normalization, why it depends on factors like the listening environment and the individual character of the content, and why the loudness range descriptor (LRA) is only reliable for speech programs.

Photo by Alexey Ruban.

Why loudness normalization is not enough

Everybody who has lived in an apartment building knows the problem: you want to enjoy a movie late at night, but you're constantly on the edge - not only because of the thrilling story, but because your index finger is hovering over the volume down button of your remote. The next loud sound effect is going to come sooner rather than later, and you want to avoid waking up your neighbors with some gunshot sounds blasting from your TV.

In our previous post, we talked about the overall loudness of a production. While that's certainly important to keep in mind, the loudness target is only an average value, ignoring how much the loudness varies within a production. The loudness target of your movie might be in the ideal range, yet the level differences between a gunshot and someone whispering can still be enormous - having you turn the volume down for the former and up for the latter.

While the average loudness might be perfect, level differences can lead to an unpleasant listening experience.

Of course, this doesn't apply to movies alone. The image above shows a podcast or radio production. The loud section is music, the very quiet section just breathing, and the remaining sections are different voices.

To be clear, we're not saying that the above example is problematic per se. There are many situations, where a big difference in levels - a high dynamic range - is justified: for instance, in a movie theater, optimized for listening and without any outside noise, or in classical music.
Also, if the dynamic range is too small, listening can be tiring.

But if you watch the same movie in an outdoor screening in the summer on a beach next to the crashing waves or in the middle of a noisy city, it can be tricky to hear the softer parts.
Spoken word usually has a smaller dynamic range, and if you produce your podcast for a target audience of train or car commuters, the dynamic range should be even smaller, adjusting for the listening situation.

Therefore, hitting the loudness target has less impact on the listening experience than level differences (dynamic range) within one file!
What makes a suitable dynamic range does not only depend on the listening environment, but also on the nature of the content itself. If the dynamic range is too small, the audio can be tiring to listen to, whereas more variability in levels can make a program more interesting, but might not work in all environments, such as a noisy car.

Dynamic range experiment in a car

Wolfgang Rein, audio technician at SWR, a public broadcaster in Germany, did an experiment to test how drivers react to programs with different dynamic ranges. They monitored to what level drivers set the car stereo depending on speed (thus noise level) and audio dynamic range.
While the results are preliminary, it seems like drivers set the volume as low as possible so that they can still understand the content, but don't get distracted by loud sounds.

As drivers adjust the volume to the loudest voice in a program, they won't understand quieter speakers in content with a high dynamic range anymore. To some degree and for short periods of time, they can compensate by focusing more on the radio program, but over time that's tiring. Therefore, if the loudness varies too much, drivers tend to switch to another program rather than adjusting the volume.
Similar results have been found in a study conducted by NPR Labs and Towson University.

On the other hand, the perception was different in pure music programs. When drivers set the volume according to louder parts, they weren't able to hear softer segments or the beginning of a song very well. But that did not matter to them as much and didn't make them want to turn up the volume or switch the program.

Listener's reaction in response to frequent loudness changes. (from John Kean, Eli Johnson, Dr. Ellyn Sheffield: Study of Audio Loudness Range for Consumers in Various Listening Modes and Ambient Noise Levels)

Loudness comfort zone

The reaction of drivers to variable loudness hints at something that BBC sound engineer Mike Thornton calls the loudness comfort zone.

Tests (...) have shown that if the short-term loudness stays within the "comfort zone" then the consumer doesn’t feel the need to reach for the remote control to adjust the volume.

In a blog post, he highlights how the series Blue Planet 2 and Planet Earth 2 might not always have been the easiest to listen to. The graph below shows an excerpt with very loud music, followed by commentary just at the bottom of the green comfort zone. Thornton writes: "with the volume set at a level that was comfortable when the music was playing we couldn’t always hear the excellent commentary from Sir David Attenborough and had to resort to turning on the subtitles to be sure we knew what Sir David was saying!"

Planet Earth 2 Loudness Plot Excerpt. Colored green: comfort zone of +3 to -5LU around the loudness target. (from Mike Thornton: BBC Blue Planet 2 Latest Show In Firing Line For Sound Issues - Are They Right?)

As already mentioned above, a good mix considers the maximum and minimum possible loudness in the target listening environment.
In a movie theater the loudness comfort zone is big (loudness can vary a lot), and loud music is part of the fun, while quiet scenes work just as well. The opposite was true in the aforementioned experiment with drivers, where the loudness comfort zone is much smaller and quiet voices are difficult to understand.

Hence, the loudness comfort zone determines how much dynamic range an audio signal can use in a specific listening environment.

How to measure dynamic range: LRA

When producing audio for various environments, it would be great to have a target value for dynamic range, (the difference between the smallest and largest signal values of an audio signal) as well. Then you could just set a dynamic range target, similarly to a loudness target.

Theoretically, the maximum possible dynamic range of a production is defined by the bit-depth of the audio format. A 16-bit recording can have a dynamic range of 96 dB; for 24-bit, it's 144 dB - which is well above the approx. 120 dB the human ear can handle. However, most of those bits are typically being used to get to a reasonable base volume. Picture a glass of water: you want it to be almost full, with some headroom so that it doesn't spill when there's a sudden movement, i.e. a bigger amplitude wave at the top.

Determining the dynamic range of a production is easier said than done, though. It depends on which signals are included in the measurement: for example, if something like background music or breathing should be considered at all.
The currently preferred method for broadcasting is called Loudness Range, LRA. It is measured in Loudness Units (LU), and takes into account everything between the 10th and the 95th percentile of a loudness distribution, after an additional gating method. In other words, the loudest 5% and quietest 10% of the audio signal are being ignored. This way, quiet breathing or an occasional loud sound effect won't affect the measurement.

Loudness distribution and LRA for the film 'The Matrix'. Figure from EBU Tech Doc 3343 (p.13).

However, the main difficulty is which signals should be included in the loudness range measurement and which ones should be gated. This is unfortunately often very subjective and difficult to define with a purely statistical method like LRA.

Where LRA falls short

Therefore, only pure speech programs give reliable LRA values that are comparable!
For instance, a typical LRA for news programs is 3 LU; for talks and discussions 5 LU is common. LRA values for features, radio dramas, movies or music very much depend on the individual character and might be in the range between 5 and 25 LU.

To further illustrate this, here are some typical LRA values, according to a paper by Thomas Lund (table 2):

Program	Loudness Range
Matrix, full movie	25.0
NBC Interstitials, Jan. 2008, all together (3:30)	9.4
Friends Episode 16	6.6
Speak Ref., Male, German, SQUAM Trk 54	6.2
Speak Ref., Female, French, SQUAM Trk 51	4.8
Speak Ref., Male, English, Sound Check	3.3
Wish You Were Here, Pink Floyd	22.1
Gilgamesh, Battle of Titans, Osaka Symph.	19.7
Don’t Cry For Me Arg., Sinead O’Conner	13.7
Beethoven Son in F, Op17, Kliegel & Tichman	12.0
Rock’n Roll Train, AC/DC	6.0
I.G.Y., Donald Fagen	3.6

LRA values of music are very unpredictable as well.
For instance, Tom Frampton measured the LRA of songs in multiple genres, and the differences within each genre are quite big. The ten pop songs that he analyzed varied in LRA between 3.7 and 12 LU, country songs between 3.6 and 14.9 LU. In the Electronic genre the individual LRAs were between 3.7 and 15.2 LU. Please see the tables at the bottom of his blog post for more details.

We at Auphonic also tried to base our Adaptive Leveler parameters on the LRA descriptor. Although it worked, it turned out that it is very difficult to set a loudness range target for diverse audio content, which does include speech, background sounds, music parts, etc. The results were not predictable and it was hard to find good target values. Therefore we developed our own algorithm to measure the dynamic range of audio signals.

In conclusion, LRA comparisons are only useful for productions with spoken word only and the LRA value is therefore not applicable as a general dynamic range target value. The more complex a production gets, the more difficult it is to make any judgment based on the LRA.
This is, because the definition of LRA is purely statistical. There's no smart measurement using classifiers that distinguish between music, speech, quiet breathing, background noises and other types of audio. One would need a more intelligent algorithm (as we use in our Adaptive Leveler), that knows which audio segments should be included and excluded from the measurement.

From theory to application: tools

Loudness and dynamic range clearly is a complicated topic. Luckily, there are tools that can help. To keep short-term loudness in range, a compressor can help control sudden changes in loudness - such as p-pops or consonants like t or k. To achieve a good mid-term loudness, i.e. a signal that doesn't go outside the comfort zone too much, a leveler is a good option. Or, just use a fader or manually adjust volume curves. And to make sure that separate productions sound consistent, loudness normalization is the way to go. We have covered all of this in-depth before.

Looking at the audio from above again, with an adaptive leveler applied it looks like this:

Leveler example. Output at the top, input with leveler envelope at the bottom.

Now, the voices are evened out and the music is at a comfortable level, while the breathing has not been touched at all.
We recently extended Auphonic's adaptive leveler, so that it is now possible to customize the dynamic range - please see adaptive leveler customization and advanced multitrack audio algorithms.
If you wanted to increase the loudness comfort zone (or dynamic range) of the standard preset by 10 dB (or LU), for example, the envelope would look like this:

Leveler with higher dynamic range, only touching sections with extremely low or extremely high loudness to fit into a specific loudness comfort zone.

When a production is done, our adaptive leveler uses classifiers to also calculate the integrated loudness and loudness range of dialog and music sections separately. This way it is possible to just compare the dialog LRA and loudness of complex productions.

Assessing the LRA and loudness of dialog and music separately.

Conclusion

Getting audio dynamics right is not easy. Yet, it is an important thing to keep in mind, because focusing on loudness normalization alone is not enough. In fact, hitting the loudness target often has less impact on the listening experience than level differences, i.e. audio dynamics.

If the dynamic range is too small, the audio can be tiring to listen to, whereas a bigger dynamic range can make a program more interesting, but might not work in loud environments, such as a noisy train.
Therefore, a good mix adapts the audio dynamic range according to the target listening environment (different loudness comfort zones in cinema, at home, in a car) and according to the nature of the content (radio feature, movie, podcast, music, etc.).

Furthermore, because the definition of the loudness range / LRA is purely statistical, only speech programs give reliable LRA values that are comparable.
More "intelligent" algorithms are in development, which use classifiers to decide which signals should be included and excluded from the dynamic range measurement.

If you understand German, take a look at our presentation about audio dynamic processing in podcasts for further information: