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Hearing - which frequencies go first

Time to Read: 8 minutes

Hearing loss is a very complex and personal process. Here at Value Hearing we want to take away the mystery and share the information you need to better understand, care for and protect your ears.

  • Understanding Hertz
  • Understanding Decibels
  • Scale of Hearing Loss
  • How good is your hearing?

Unfortunately a degree of hearing loss is unavoidable as we age - especially at the far ends of the hearing spectrum as hair cells in the cochlea don’t regenerate as they die off.

Those hair cells are important because they’re tuned to different frequencies which are sent to the brain for processing. The high frequencies goes first because the hair cells that detect higher pitches are the first to receive the sound waves - so they work much harder than the rest.

When understanding your hearing loss, you might see the information expressed in Hertz and Decibels.

Understanding Hertz

Hertz (Hz) is a unit of measure. Specifically it measures smooth periodic oscillation and represents these as cycles per second.

In simple terms, Hertz measures the pitch of sound. The more frequent the oscillations per second, the higher the pitch of the sound and the higher the number in Hz. Babies can hear sounds pitched between 20Hz to 20,000Hz.

As we get older, we lose those higher ranges. Younger people can hear frequencies as high as 15,000Hz but the figure drops to 12,000Hz for the over 50s.

But frequency is one half of the equation. The other half is decibels which, in broad terms, is about the loudness of a sound.

Understanding Decibels

The loudness of a sound is measured in decibels but unlike distance or temperature, sound isn’t measured on a linear scale. Decibels works on a logarithmic scale.

Loudness of a sound is all relative - the sound of a jackhammer is going to register a different loudness at one metre away than at twenty metres away.

When it comes to measuring hearing, your audiologist tests your ability to hear different pitched sounds and the volumes needed before you hear them.

Normal hearing means you can hear a particular pure tone sound between 0dB to 20dB. It might very well be that your hearing is within normal range in some frequencies and not in others.

Scale of Hearing Loss

How many frequencies are below this threshold will tell you what type of hearing loss you may have. The information is represented graphically in your audiogram and will reveal where your hearing falls on a four point scale:

  • Mild
  • Moderate
  • Severe
  • Profound

Mild

The quietest sound you will be able to hear is between 25-40dB which includes faint bird calls, a whispered conversation, the sound of your computer fan.

People with mild hearing loss find it difficult to follow a conversation when there are competing sounds, such as a busy restaurant, or if there are several people talking at once. You would also have trouble hearing the sound of leaves rustling in the wind, or the gentle sound of a babbling brook.

Moderate

The decibel threshold for people with moderate hearing loss is 40-70dB. This means you have trouble hearing someone speak even in quiet situations. Sounds in this frequency include a coffee percolator, the dishwasher operation, the sound of a shower running.

Sounds below this threshold are difficult to hear without assistance.

Severe

People who have severe hearing loss have difficulty hearing sounds that are below 70-90dB. Sounds in this range include a running vacuum cleaner, an alarm clock, or a passing car.

If this seems familiar, it might be that you’re using lip reading much of the time in conversations with one person even in quiet environments.

Profound

Profound hearing loss is defined as people who can only hear sounds over 95dB which include an electric drill, riding a motorcycle and a power saw.

How good is your hearing?

Hearing a baby laugh is one of the delightful sounds you might be missing out on.

In 2012 The UK Telegraph published a list of Britain's top 10 favourite sounds - we’re all familiar with them, but if your hearing is not up to par you might not be able to hear them!

TOP 10 MOST LOVED SOUNDS

  1. Waves against rocks. The most loved sound is the loudest of all. The majestic booming sound of waves crashing on the rocks is an awe inspiring 60 to 78dB depending on the height of the waves.
  2. Rain against the windows. When you are home safe inside, rain on the windows is comforting sound. Moderately falling rain is about 50dB. Gently falling rain will be a softer sound still.
  3. Treading on snow. The muffled, squeaky crunch underfoot was nominated as England’s third favourite sound.
  4. Baby laughing. The uninhibited delight of a baby’s laughter brings joy to everyone who hears it.
  5. Birds chirping. There’s something charming about a full throated bird bursting into song. Sweet little trills are about 15dB.
  6. Crackling open fire. The pops and crackles of a comforting winter’s fire is around about 15dB.
  7. People laughing. There is nothing more joyous than hearing family and friends laugh. It truly does make the world go round. You’ll need hearing that can hear sounds above 60-65dB.
  8. Leaves crunching beneath your feet. Possibly about 15-20dB. Did you know that the sound of rustling leaves has its name - psithurism. It doesn’t sound quite as evocative as "rustling" does it?
  9. Cat purring. A typical cat’s purr is 25dB but Merlin the cat is the reigning Guinness World Record holder for a purr as loud at 67.8dB measured at one metre away - that's as loud as a vacuum cleaner!
  10. Church bells in the distance. “The distance” is the operative word. Church bells are rung in celebration are delightfully uplifting. Up close, ringing church bells are very noisy 85dB.

If you can’t remember the last time you heard some of these sounds, then it might be time to get your hearing checked. You might be surprised at the sounds you’ve been missing!