Tag Archives: hearing

Sound Check: Using IEMs and Retraining Your Brain to Hear Safe Sound

A post-pandemic return to live music is an opportunity for musicians to re-evaluate hearing health—and to modulate audio levels to reduce the inherent risk of hearing impairment.

After more than a year away from a typical concert venue—amid virtual performances—musicians have naturally adjusted their volume to a controlled listening regimen. According to Michael Santucci, Au.D., a researcher and expert who specializes in hearing conservation, now is an ideal time to make a change and modify onstage sound to more judicious levels.

“It’s a new normal,” he says. “This return from a year of downtime gives our industry a unique opportunity to include hearing in our expanded health consciousness. This is our ears letting us know it’s OK to dial back the audio levels.”

With huge PA systems and wedge monitors on stage, everything is cranked up. Before concert halls and stadiums begin to fill up, it’s time to turn down the sound. Santucci regularly works with musicians on custom-fitted in-ear monitors and earphones to protect hearing, allowing artists to achieve optimal richness in sound at safe exposure levels. “Today, we have the technology to let every musician and engineer hear in high-resolution detail at lower audio levels,” he says.

These days, in addition to rock musicians, he counts among his clients a number of orchestra musicians. Whether it’s creating impact with louder fortissimos or to entice new listeners with pops and Broadway music, orchestras have become louder. The added decibel (dB) quotient can be deafening to musicians, and Santucci says, “The risk goes up with volume and length of exposure.”

Personal In-ear monitors (IEMs) deliver exceptional sound quality. Properly fitted IEMs offer significant isolation from unwanted ambient sound, reducing the noise floor (background noise and noise that equipment naturally creates) and allowing the monitor mix to be heard with full clarity. Using IEMs also puts monitoring level control in the hands of the performer. Santucci says, “When things get too loud, there is no excuse for not turning monitors down to a comfortable level.”

According to National Institute for Occupational Safety & Health (NIOSH), workday exposure levels above 80 dB(A) can cause long-term hearing injury. Higher levels reduce the amount of time before that occurs. For every additional 3 dB, the safe exposure time is cut in half. At 100 dB(A), safe exposure time is only 15 minutes—a definite threat to hearing health.

Use Isolating Earphones

Personal In-ear monitors can go a long way toward saving your hearing, but only when used properly. Monitoring at lower levels is the key, and this is accomplished through adequate isolation and smart volume settings. Used correctly, professional isolating earphones, combined with audiologist consultation, offer the best possible solution for musicians interested in protecting their most valuable asset—their ears.

Use Both Earphones

One distressingly common practice is using only one earphone, leaving the other ear open. Performers have several excuses for this, such as not wanting to feel “removed” from the audience. But the fact is, our ears are designed to work together. By removing one earpiece, the other one sounds 6 dB quieter, which usually results in the performer turning it up. At the same time, the other ear is completely unprotected. “From a hearing health perspective, wearing only one earpiece is a disaster,” notes Santucci. “Always use both earphones, which will enable overall lower listening levels while delivering full stereo sound.”

Keep the Limiter on

Unexpected sounds— someone unplugging a phantom-powered microphone or a blast of RF noise—can cause a near-instantaneous peak in excess of 130 dB SPL, the equivalent of a gun shot at your eardrum. A brick-wall type limiter can effectively prevent these bursts from reaching damaging levels. For this reason, your personal monitor signal chain should always include a limiter at the receiver. A well-designed limiter will not adversely affect the audio quality, as it only works on these unexpected peaks.

Listen to Your Ears!

Hearing issues after rehearsal or performance are warning signs of overexposure. Common examples are:

  • Temporary Threshold Shift (TTS) —a “stuffiness” or compressed feeling, as if someone stuck cotton in your ears
  • Tinnitus—a persistent ringing or buzzing in the ears

These are the ear’s way of warning you that your hearing is in danger, although hearing injury can also occur without them. Hearing issues often start off as temporary, but are more persistent over time, eventually becoming permanent. The good news is that changing listening habits can keep the damage from getting worse. Performers who regularly experience the above effects are definitely monitoring too loud. They should see an audiologist—and turn it down!

Have Your Hearing Checked Regularly

The only way to know for sure if your listening habits are safe is to get your hearing checked regularly. The first hearing test establishes a baseline that all future hearing exams are compared against to determine if any loss has occurred. Musicians should have their hearing checked at least once a year. If hearing loss is caught early, corrections can be made to prevent further injury.

The beauty of personal in-ear monitors is that you can turn the volume down while getting improved sound quality and convenience, putting you back in control of your sound—and your hearing wellness. This year’s post-pandemic return to the stage is the perfect time to make a behavioral shift.

Sensaphonics 3DME Custom Tour IEM System

Tour-Ready In-Ear Monitor System

The Sensaphonics 3DME Custom Tour is a custom-fit IEM system that captures room sound with full 3D directionality. The ambient sound is added to the monitor feed via the system’s USB-rechargeable bodypack mixer, at levels fully controlled by the user. The bodypack also houses signal processing, including a seven-band stereo graphic equalizer (EQ) and limiter, and has a battery life of eight hours. The IEMs feature a balanced, neutral sound that can be tuned to personal preference via its Bluetooth control of the system’s app.

www.Sensaphonics.com

acoustic shock

Too Loud, Too Close, Too Long: Musicians Suffer Career Ending Acoustic Shock

acoustic shockIn the symphonic world, a crescendo makes for a dramatic finale, but it can have serious consequences for musicians. Recently, in an unprecedented court ruling, British viola player Chris Goldscheider, 40, won a landmark High Court judgment against Royal Opera House when he suffered career ending hearing loss from a rehearsal of Wagner’s Die Walkure. Seated directly in front of the brass section, he suffered acoustic shock, the result of sound that exceeded 130 decibels.

It’s a story that cellist Janet Horvath knows too well. The former associate principal cello for the Minnesota Orchestra, sustained an acoustic-shock injury to her left ear in 2006 after a one-time concert.

That night, the drum set, piano, electric guitars, keyboard, and conductor were positioned directly in front of her for a pops concert that included Broadway singers. Horvath was wearing musician’s earplugs, but one speaker was no more than two feet from her left ear. Eight speakers blasted music back toward the musicians. She says, “I felt it instantly; it was excruciating. When the concert was over, I took out my earplugs and could not bear to hear anyone talking. It never subsided.” She took a few months off to heal, but she needed to wear her left earplug. She compensated, relying on her right ear, and continued to be exposed to high decibels.

By 2009, her right ear, like the left, could no longer tolerate normal sound. After several doctors, she was diagnosed with hyperacusis, an auditory injury caused by repeated exposure to high decibels or a single acoustic shock. In 2010, she had to leave the orchestra that was her home for nearly 34 years.

She says, “It was characterized by abnormal sensitivity—the total breakdown of tolerance to all sound. I couldn’t leave the house. There was pain in my ear, teeth, tongue, it radiated down my neck. You actually fear sound. Many people with hyperacusis become hermits.”

The problem is prevalent, especially among woodwind players, Horvath says. “There is more awareness of the condition and I was lucky to have found physicians who helped me retrain my brain. I was fitted with special hearing aids, which turned sound down.”

“It was painstaking training that took more than two years of slowly increasing sound. I am aware of limits and decibels,” she says. Today she is mostly cured, but avoids loud restaurants and sports events. She can finally attend concerts and plays chamber music.

Noise-induced hearing loss is a combination of exposure time, noise level, peak level, and proximity to the sound. Being aware of decibel levels is important. Horvath explains, “If you know you will be playing Mahler, it’s not a day to mow your lawn.” Horvath maintains that silence is as critical to musicians as making sound. “It would be smart to have rooms where musicians can go to have silence.”

Minnesota Orchestra has an audiologist come in to offer hearing tests and fit musicians for earplugs. According to Horvath, this could be precedent-setting. No one wants to get sued so they’re now willing to take further steps to protect their musicians’ hearing. She hopes, too, that conductors will begin to alternate the repertoire to give musicians a break.

OSHA limits the number of decibels one can be exposed to per day. The decibel level of an average two-hour concert generally exceeds OSHA’s recommendations. And there are no regulations for intermittent loud blasts. Horvath adds that OSHA only talks about hearing loss as a disability when you can no longer hear speech. 

In the hall where the Minnesota Orchestra regularly performs, they have made modifications. “Our orchestra has always been on the cutting edge, partly because of my work. Their stage manager was one of the first to build a Plexiglass shield,” she says.

Horvath has written a number of books, including Playing Less Hurt: An Injury Prevention Guide for Musicians. She is a recognized authority in the area of medical problems of musicians and a recipient of the Richard J. Lederman Lecture Award presented by the Performing Arts Medicine Association. She conducts seminars across the country and regularly appears on national radio and television.

Music Induced Hearing Disorder

Hearing Protection Is Key for Today’s Orchestra Musicians

Studies have shown that musicians have more than three times the average risk for hearing loss. The risk of developing a music induced hearing disorder (MIHD) should be a major concern for orchestra musicians. According to Heather Malyuk, AuD, who has worked with both Chicago Lyric Opera Orchestra and National Symphony Orchestra, orchestra exposure to sound is difficult to study due to variables in repertoire and orchestra size. However, more than half of orchestra musicians surveyed have experienced MIHDs.

“These musicians are highly susceptible to MIHDs, including tinnitus (ringing in the ears), hyperacusis (sensitivity), diplacusis (detuned pitch perception), and distortion,” she says. MIHDs are more likely than modest hearing loss to affect a musician’s career, yet they are seldom discussed.

“It’s easy to forget musicians are everyday people susceptible to other causes of hearing loss such as disease, poor vascular health, sudden loss, genetics, strong medications, and lifestyle choices,” she says. “Musicians’ brains are amazing in their plasticity to adapt and adjust to changes in hearing. They are often afraid to discuss hearing for fear of losing work or negative perceptions from peers. Hopefully, that will change. If we are open and educated about these issues as a group, we can more effectively prevent them.”

Music Induced Hearing Disorder

Though hearing damage is often associated with louder instruments, every instrument group is at risk. “Injury is not from volume alone, but volume and length of exposure time. Practice, rehearsal, and performance create many hours of exposure,” she explains. “The US doesn’t have regulations or safety scales unique to music, but musicians can use the scales designed for industry workers to effectively protect hearing.” These scales measure noise levels in decibels (dBA).

The Occupational Safety and Health Administration (OSHA) regulatory scale states that 90 dBA of sound is safe for eight hours. The safe time is halved every time the sound intensity increases by five decibels. The National Institute of Occupational Safety and Health (NIOSH) scale is more stringent, starting at 85 dBA for eight hours, with the safe exposure time halved every time the sound intensity increases three decibels. (See table.) Musicians should consult with specialized audiologists to assess their risks.

Members of symphony orchestras are exposed to all kinds of noise in their daily lives, plus the sound of all the other instruments in the orchestra. (See sample noise level charts.) Adding to this is the current popularity of pop stars guest performing with orchestras. “Pops-style concerts have changed the way orchestral musicians listen and protect themselves. They are a driving factor in the pursuit of hearing wellness,” Malyuk says.

According to Malyuk, more must be done to protect orchestra musicians. “Occasionally hearing protection is provided, often in the form of foam, universal fit earplugs. Orchestras are not required to provide hearing protection, so it is a nice gesture, but often an incorrect one, as these are virtually unusable in professional orchestral environments,” she says. They are not designed for music and don’t have a flat frequency response (dampening high pitches more than low pitches), making it difficult for musicians to hear subtle nuances of music.

Other “engineering controls” are sometimes implemented to protect hearing. “Baffles can be used, but they are often expensive, tricky to deploy, and vary in terms of attenuation, depending on make and positioning. In theory, changing orchestral seating can reduce levels by a few decibels, but this affects instrumental balance for the audience,” she explains. Solutions like rotating string players and limiting louder repertoire are also not feasible in the orchestra setting.

“Giving the auditory system breaks is healthy, but it all comes down to repertoire and sound levels,” she says. “If decibel measurements can be taken on each individual player, then educated choices about breaks can be made. However, that can be costly and time consuming, and orchestras can’t conduct such a study on each piece of music.”

In-ear monitors (IEMs), when used correctly, help many musicians to hear themselves and their colleagues accurately, while also protecting hearing. “It’s possible for orchestras to use IEMs, but logistical issues stand in the way. For musicians to have personal audio mixes, extra gear is needed,” says Malyuk. “Two members of the National Symphony Orchestra have used ambient IEMs for pops performances, and I’ve fit several musicians with these devices as active variable level earplugs, used without a monitor feed. But, filtered earplugs are currently the best option for orchestral players because they are less expensive and less cumbersome.”

Some musicians are resistant to earplugs due to past experiences. “I’ve found that this is usually because they’ve been fit incorrectly,” she says. “It takes a knowledgeable, specialized audiologist to choose the best quality filter, select usable but effective attenuation, and take accurate ear impressions. Just like any area of health care, audiology has specialties.” She recommends an annual wellness visit with a specialized audiologist to check for MIHDs and hearing loss and to learn about the latest protective measures like filtered earplugs.

More often hearing protection is becoming a subject of orchestra committee discussions. “Recently, the affordability and necessity of hearing wellness programs for orchestra members has been a focus in negotiations. Education is needed in this area and that falls on the shoulders of orchestra committees, who are often underequipped for that task,” says Malyuk. This is an area where trained audiologists can assist, providing current research, cost points, and risks, as well as information regarding wellness programs and hearing protection options.

“A common arrangement I have seen within collective bargaining agreements is a reimbursement program. Musicians pay for the wellness visit and custom hearing protection costs and are reimbursed a certain, agreed upon percentage. Annual hearing wellness care is not only best for the musicians, but it also helps protect employers (such as orchestra management) from potential legal action for hearing injury,” she says. “Musicians are small muscle athletes and, as such, need annual care for their most valuable instrument—their ears.”

Heather Malyuk, AuD has spoken at ICSOM and ROPA conferences. Her clinic, Soundcheck Audiology (www.soundcheckaudiology.com), features concierge services for orchestras, supporting musicians through hearing wellness and MIHD prevention.

IEMs

Safe Sound in an Age of Living Loud: Correct and Safe Use of In-Ear Monitors

IEMsIn a loud stage environment, musicians become accustomed to hearing their monitor mix at high volume. Some use in-ear monitoring systems (IEMs) to reduce the impact, but if the volume on the device is not regulated and lowered, it’s no solution. IMEs are only considered protective devices if they are used at safe levels.

IEMs are in demand because they isolate the ear from ambient noise and artists can hear the intended signal clearly, at a much lower volume. Critical to the equation, though, says Michael Santucci, Au.D., a researcher and expert who specializes in hearing conservation, is much lower volume. It requires modifying user behavior and listening patterns.

Look no further than the iPod. Studies have shown, in case after case (especially with teenagers), that there was irreversible damage because of volume and prolonged listening. Do most musicians use ear protection? “No,” says Santucci, “Are attitudes changing? Absolutely.” 

It’s like sun exposure, he explains: it’s both how strong it is and how long you’re exposed. In music, it’s personal susceptibility, how loud, and how many hours you’re in it. “We do pit crews for Broadway plays. Is it terribly loud? Not always, but they’re doing it six hours a day.” Nowadays, Santucci frequently works with orchestras because they are featuring more pop stars. The added decibel (dB) quotient can be deafening to orchestra members. Santucci says, “Risk goes up with volume and length of exposure.”

A recent study out of Vanderbilt University showed that, regardless of whether they used floor wedges or IEMs, subjects turned them up to their usual listening level. Everybody had three days of in-ear and three days of floor wedges at different times and in different venues. Every musician turned to exactly the same loudness every day.

“If you’ve been practicing guitar for years at 110 dB with wedges, the natural tendency will be to turn your IEMs to 110 dB, even if it’s not needed,” Santucci says. “And until the audiologist says you need to turn it down to here, their brains tell them to go back to the level they’re used to.”

The good news is that the second part of the study showed that musicians can recalibrate their brains to listen at a lower level. After a couple of weeks, it becomes the norm. Santucci says, “It’s habit—like the timbre of your instrument, pitch—it’s all because you’ve done it a million times. Loudness goes right along with it.”

Adding Ambient Sound

Some musicians say they feel disconnected from the band and the crowd with IEMs. This can be addressed in a few ways. The trick, Santucci says, is to do so without compromising the isolation of the IEM system. A simple remedy is for the sound engineer to set up audience mikes to add to the monitor mix so the artist can get a feel for the room. “Some musicians take out one IEM, which is very damaging to hearing. They end up turning up the side with the ear monitor even louder, plus they have an open ear not protected by anything.”

For a natural, but more robust, method of adding ambient sound into the IEM mix, Santucci recommends 3D active ambient IEM systems that allow the musicians to control how much ambient sound is heard. “What I do not recommend is porting the earphone to let ambient sound leak. Porting effectively eliminates the benefits of isolation and cannot be controlled, it has the potential for the user to turn up the volume of the system to unsafe levels.” 

Safe Listening

For hearing conservation benefits of in-ear monitors, refer to OSHA and NOISH guidelines to determine exposure times for safe use. Shows of less than one or two hours are less of a problem. For a club band, whose shows may go on for several sets of three or more hours, volume levels must be much lower and should average no more than 95 to 97 dB.

The problem is being able to accurately determine the decibel level coming from the in-ear monitors. Currently, the only method to measure these levels is with ear-probe microphone technology used during rehearsals or sound checks by an audiologist. From these readings, a volume level can be recommended based on the length of a show.

Tinnitus and Hearing Loss

If your ears ring or if you have trouble hearing after a concert, you are definitely in danger of noise induced hearing loss (NIHL). Santucci cautions, “Even if your ears don’t ring, if you think it’s safe, you’re wrong. Research shows that, of those suffering from NIHL, only 30% experienced ‘ringing’ as a warning sign. In other words, if your ears ring after a performance, you’re too loud. But if they don’t ring, there’s a 70% chance you may still be damaging your ears, if levels exceed OSHA safe exposure limits.”

For additional information, visit the websites: www.osha.gov/SLTC/noisehearingconservation or www.cdc.gov/niosh.

Other Hearing Protection Tips:

  • Invest in superior hearing protection,
    custommade ear molds with dampening filters.
    Preferably use musicians’ earplugs, which offer flat attenuation vs. traditional earplugs, which tend to filter sound from higher frequencies, resulting in a muffled sound.
  • Protect your ears consistently every time you may be exposed to loud music and/or sounds, not just when you are performing.
  • Better yet, avoid noise as much as possible when you are not performing.
  • Invest in high-quality in-ear monitors and train your ears to use the lowest level that’s feasible.
  • Drummers should use dampening pads when possible.
  • Sound travels in a straight line so it’s louder directly in front of or behind a speaker. Spread out so you are not being blasted by the musician next to you. Move away from on-stage monitors and amplifiers.
  • If moving away is not an option, look into using baffles to protect yourself.
  • Take breaks of 15 minutes in between sets of music or rehearsals to give ears a rest. During rest periods go outside or somewhere quiet.
  • Whenever possible, practice at lower volume
    or play your electrified instrument unplugged.
  • Use smaller amps when possible.
  • Avoid ear buds and other direct-injection earphones for recreational listening, especially in loud environments.
  • Have your hearing tested frequently by an audiologist.
  • If it’s not possible to have regular professional sound-level assessments, at least use a sound meter app to check your exposure level.
  • Avoid signing up for repeated live gigs at loud clubs. If possible, give your ears some recovery time in between.

Michael Santucci, Au.D. works with the Audio Engineering Society (AES), where he is vice chair of the Technical Committee on Hearing and Hearing Loss Prevention. He operates a Musicians Hearing Clinic and works on hearing conservation through Sensaphonics: In-Ear Monitoring Systems.

When the Sound Won’t Stop – 3 Ways to Battle Tinnitus

For musicians, tinnitus is an occupational hazard. Beethoven was famously afflicted. According to Hearing Education and Awareness for Rockers (HEAR), nearly 60% of the Rock and Roll Hall of Fame’s inductees are hearing impaired, many suffering from bouts of tinnitus. Although almost always described as a constant ringing in the ears, there is a litany of sounds that sufferers ascribe to the noise: clicking, humming, hissing, buzzing, piercing, throbbing, roaring, whooshing, or chirping—much like an orchestra of cicadas. 

Following a deafening noise, a car accident, or an especially loud concert, the average person will experience some form of tinnitus, but only a small percentage of the population lives with it. A rare kind, called objective tinnitus, or rhythmic, is associated with circulation and vascular problems because it often keeps time with the person’s heartbeat. A doctor can hear it with a stethoscope which, although still aggravating for the patient, can at least be heard by someone else. Subjective tinnitus, on the other hand, the most common kind, is only heard by the sufferer, but emits a seemingly phantom, yet deafening, noise.

Research shows that hearing loss results in less external sound stimuli reaching the brain. In response, the brain changes how it processes different sound frequencies, called maladaptive neuroplastic changes. Delicate hairs in the inner ear move to the pressure of sound waves, which triggers cells to release an electrical signal through the auditory nerve to the brain. The brain interprets these signals as sound. If the hairs inside the inner ear are bent or broken, they can leak random electrical impulses to the brain, resulting in ear ringing.

The American Tinnitus Association (ATA) estimates that 20 million people have “burdensome” tinnitus, and two million have “extreme and debilitating” cases. Most patients develop tinnitus as a symptom of hearing loss caused by age, long-term damage, or acute trauma to the auditory system. When the ringing occurs on one side of the brain it may be indicative of something more sinister, like a tumor. Ménière’s disease also affects the inner ear, causing vertigo, ringing, and eventual loss of hearing. 

3 Ways to Battle Tinnitus

People with tinnitus can find relief by using hearing aids and other sound-amplification devices. Like a microphone, amplifier, or speaker, hearing aids can supplement the volume of outside noise and increase the amount of sound stimuli received and processed by the body’s auditory system. A good sound therapy plan takes into account individual needs, but the most important factor is to provide background sound in a consistent, systematic way to encourage habituation.

Ear-Level Sound Generators—Ear-level sound therapy devices are worn on the ear, like a hearing aid, and deliver a variety of predetermined or programmable therapeutic sounds. They are appropriate for individuals with minimal hearing loss.

The sounds most commonly available are broadband sounds that many tinnitus patients find tolerable—rainfall or flowing water, for example. Some devices offer preset broadband sounds, and some offer broadband sounds that can be modified.

Any of these devices can deliver a controlled, consistent sound to the ears. This should provide not only some relief but also a feeling of control over tinnitus, which will aid habituation. The volume should be set to a very comfortable level that does not interfere with your ability to concentrate or communicate.

Hearing Aids—Normally intended to improve speech comprehension in a wide range of listening environments, hearing aids can also be programmed in ways that provide therapeutic intervention for tinnitus. The frequency of tinnitus is usually within the range of frequencies included in an individual’s hearing loss. For some people with tinnitus, the use of hearing aids to amplify sound in the range of their hearing loss can also help reduce their perception of their tinnitus.

Combination Units—A combination unit is an ear-level device combining the amplification of a hearing aid with background sound like a sound generator. The devices have an assortment of background noises, including a preset broadband noise, an adjustable broadband noise, and random chime-like tones. Look for a device that allows you to adjust the hearing aid volume and the generated sound volume separately. 

Now that most hearing aids have wireless Bluetooth capability, it is possible to stream additional sounds through hearing aids and combination units. As a result, any Bluetooth-capable device can be made into a customized combination unit.

Brazilian Court Makes McDonald’s Accountable

McDonald’s workers, labor leaders, and elected officials from five continents testified before a Brazilian Senate committee last week. The hearing comes as the fight for $15 per hour grows internationally. The workers, including one from Chicago, spoke about the companies labor practices.

Brazilian Senator Paulo Paim, who spearheaded the Senate hearing and chairs the Brazilian Senate’s Human Rights and Participative Legislation Committee said in a statement: “McDonald’s is one of the most recognized brands around the world, and this hearing makes clear that its corrosive business model spans the globe as well. Brazil can be the country that leads the way in holding this company accountable. Let this hearing mark a moment where governments around the world join together to demand that global companies like McDonald’s do better by workers and the public as a whole.”

H.E.A.R. Day New York Honors Les Paul

Last week on H.E.A.R. Day New York a panel of medical and health experts discussed the importance of improving hearing conservations for performers, professionals, and those who enjoy listening to music as well. This year Les Paul was honored with the H.E.A.R Leadership Award.

Kathy Peck, ED of H.E.A.R. has this to say:

“Les Paul was a friend of H.E.A.R. Les knew that further work was going to be necessary in the area of music hearing conservation. Now, along with partner the Les Paul Foundation and others, H.E.A.R. presents schools with Listen Smart Workshops and the Listen Smart Film Series that will allow us to continue our mission in providing services and educating the public to hearing conservation.”

We all know musicians suffer from a lot of hearing issues, and that’s why a cause like this is so important. To raise awareness of the real dangers and come up with ways to prevent those dangers from occurring.

Make sure you check out their site hearnet.com for more information.