Noise is the constant soundtrack of our daily lives. It takes on many different forms: construction work, blaring televisions, hooting taxis, hairdryers, loud music and any other sound that bothers or causes harm to people. The way in which we perceive sounds and tones is based on personal preference. What one person regards as melodic can be an ear-splitting noise to another. So how loud is too loud?
Sounds and tones travel in waves and are measured in frequency and amplitude. The amplitude determines how forceful a sound wave is by measuring the change in atmospheric pressure that it has. A sound wave is measured in decibels of sound pressure.
According to America’s National Institute on Deafness and Other Communication Disorders (NIDCD), the suggested safe sound exposure limit is 85 decibels for eight hours a day. This is the same decibel level as city traffic.
According to DangerousDecibels.org, a raindrop is recorded as a faint 40 decibels, a conversation is a moderate 60 decibels and an iPod at peak volume is an intense 115 decibels. At 120 decibels, the average rock concert can cause damage to your hearing after only seven and a half minutes. According to GenerationDeaf.com, noise measuring 120 decibels is roughly as loud as a firecracker and “is the point where your ears interpret the level of sound as physically painful”.
Excessive exposure to dangerous noise levels for extended periods of time causes Noise-Induced Hearing Loss (NIHL). This destroys the delicate hair cells, called stereocilia, found in the inner ear that are crucial for hearing
Previously, scientists believed that the hair cells were damaged by the vibrations caused by loud sounds. However, recent studies have found that exposure to loud noise triggers the formation of free radicals, which damage and even kill the hair cells.
A reduced sense of hearing at specific frequencies is one of the first indications of NIHL. This usually affects the basic level of hearing needed to comprehend what people are saying, making communication difficult. Another common symptom of NIHL is tinnitus, which is a buzzing, ringing or cracking sound in the ear. Tinnitus can be a permanent condition, but many people experience temporary tinnitus after a night out at a club.
Craig Jackson, a second-year BA student and musician, says that, “After a show my ears buzz for a little while. I try to wear noise-reducing earphones or in-ear monitors as much as possible to avoid it, but the buzzing is especially apparent when I am in a quiet room after a show.”
Another common symptom of NIHL is acoustic trauma, which causes immediate and permanent damage to hearing. This damage is the result of a short loud blast such as an explosion, gunshot or firecracker.
Many people damage their hearing by listening to their iPod on full volume. Emmah Morton, a second-year BA law student, says “I often catch the bus between Hatfield and LC de Villiers and notice the number of students listening to music, through earphones, so loud that I can sing along to their song. I think that it is unhealthy to listen to your music that loud.”
GenerationDeaf.com gives guidelines for the amount of time a person should listen to music through headphones in accordance to different volume levels. The suggested listening times are a maximum of five minutes per day at 100% volume, a maximum of 80 minutes per day at 80% and a maximum of 18 hours at 60%. There is no limit for volume below 50 percent.
The Hear the World Foundation says that you should give yourself a hearing “downtime” when listening to music in order to prevent NIHL. Ideally, this downtime period should be 24-48 hours long and not less than 12 hours. This allows your ears to rest and recuperate from loud sounds and noisy activities.
According to the Hear the World Foundation, noise has an impact on the entire body. “Low noise levels can trigger the release of stress levels, leading to increased blood pressure. This in turn can lead to aggressive behaviour and tensions in interactions with other people, as well as increased risk of stroke, heart attack and tinnitus. Unwanted sources of noise also prevent relaxation, recovery and sleep. They can also impair concentration and performance, particularly in children.”
Our sense of hearing is important. It gives us pleasure when we listen to music, it enables us to protect ourselves by alerting us to potential danger, but most importantly, it allows us to interact and communicate with other people. The good news is, with a little bit of precaution you can enjoy the full benefits of your hearing for many years to come.
Photo: Charlotte Bastiaanse