normal mild moderate mid-severe profound Frequency in Hertz (Hz) H e a r i n g L e v e l i n D e c i b e l s ( D B ) severe -10 0 10 20 30 40 50 60 70 80 90 100 110 120 250 500 750 1000 1500 2000 3000 4000 60 D R T E D V E N E M A NOISE-INDUCED HEARING LOSS Dr Ted Venema Audiologist/Teaching Professor After age-related hearing loss (Presbycusis), noise-induced hearing loss (NIHL) is the second most common cause of hearing loss and affects both young and old. Studies show that elderly people in less-developed countries have better hearing than their counterparts here, because they haven’t been exposed to as much noise pollution. But younger people everywhere in today’s world are at risk from NIHL, especially when not wearing earplugs while working with loud machinery or listening to loud music (especially while wearing head- phones or ear buds). Sound intensity is measured in decibels of hear- ing level (dB HL). A whisper is about 30 to 40dB HL, normal speech is about 50-60dB HL, and shouting is about 80 to 90dB HL. Lawn mowers and loud music at concerts are about 90 to 95dB HL, circular saws and jack hammers are about 100 to 110dB HL, and a screaming jet engine is about 120dB HL. Two things to consider here are the noise intensity and the length of exposure to it. Generally, the louder the sounds, the shorter the time those sounds can be tol- erated without causing permanent NIHL. For example, 80dB HL might be tolerated in an 8-hour work day. But each time the noise level is increased by 5dB, the time exposure sufficient to cause NIHL will be cut in half. The ringing in the ears after a rock concert or exposure to some other loud noise is a strong warning of perma- nent NIHL risk. The tiny hair cells inside the inner ear, or cochlea, are bent by incoming sound. When too much loud noise blasts and flattens those hairs cells, the mes- sage to the brain will be that it is hearing a sound when there is no sound. Over time, the hairs will stand up again as the ringing goes away, but if exposed to loud noise over and over again, those hair cells will become forever bent and damaged. An audiogram may show that hearing loss is evident in high frequencies around 4000Hz. High-pitched speech sounds (like f, s, sh, ch, th, k), while audible, are not understandable and sound like mumbling. The natural resonance of the outer ear and ear canal is caused precisely by the unique shape of the outer ear and the length of the ear canal. With normal hearing, softer high-pitched consonant sounds of speech are naturally increased in loudness so as to be better-heard. Excessive noise, however, causes a mirror image of this unique res- onance, as can be seen by the shape on an audiogram. While NIHL is entirely preventable, the sad thing is that it is permanent. Lauren Robinson, B.SC., RHIP Audiologist/Owner NexGen Hearing Parksville BC As the owner of NexGen Hearing Parks- ville, Lauren has been involved in hearing health since 2010. Born in Ontario, she made the move west to study Linguistics and Psychology in Victoria. After finishing her Bachelor of Science, she pursued further education to become a Registered Hearing Instrument Practitioner. Lauren loves getting to know her clients and finding a lasting solution to improve their quality of life. She lives in Nanaimo with her husband and son, and loves to travel, hike and spend time on the ocean. She looks forward to meeting you! MEET YOUR HEARING PROFESSIONAL: LAUREN ROBINSON Travel enthusiast NEXT GENERATION OF HEARING CARE | 26 25 | HEARING TODAY