Low Frequency Hearing Loss or “Reverse Slope” Hearing Loss
The most common type of hearing loss is high frequency hearing loss. Of the estimated 36 million hard of hearing people in the United States, only a few percent of those individuals suffer from low frequency hearing loss, or as it is commonly referred to, “reverse slope” hearing loss. See that audiogram to the left? Many audiograms look like the mirror opposite. With high frequency losses, the scores in the low frequencies are good (up high on the chart), and they drop or “slope” down to the high frequencies. Due to the shape of this sudden drop, you’ll often hear high frequency hearing losses referred to as “ski slope” losses. So a low frequency loss is really just the opposite, or a “reverse slope.”
A lot of times an Otolaryngologist won’t be able to pin-point the exact cause of a low frequency hearing loss, but it is usually one of the following. First, there is a good chance that like most hearing loss, it could be hereditary. Aside from that, there are a few other main causes. It has recently been discovered that a gene mutation, called Wolfram Syndrome may cause low frequency hearing loss. Other causes of low frequency hearing loss include sudden hearing loss and Meniere’s disease.
With traditional, high frequency hearing losses, folks tend to have a hard time understanding speech- since most of the clarity of speech comes from high frequency sounds. However, if you have a low frequency loss, you may hear the mid and high frequencies just fine, and those will tend to make up for the loss in the lower frequencies (where there is not a lot of speech information). For this reason, individuals with low frequency hearing losses can often still understand speech very well. Due to this, low frequency hearing loss can be harder to detect than a high frequency loss.
One of the most common complaints among those with a reverse slope hearing loss is difficulty hearing on the phone. Many people with a high frequency loss do “ok” on the phone, because speech through the phone presents in the low and mid-frequencies. For this reason, hearing on the phone can be very difficult for those with a low frequency loss. If you have this problem, you might want to look in to CaptionCall, which is a free service that converts speech to text automatically during phone calls so you can read what the person on the other end of the line is saying. With a reverse slope loss, it is also very hard to hear accents. Many people with a reverse slope loss will report that listening to people with accents sounds like listening to Charlie Brown’s teacher.
If you suffer with low frequency hearing loss, you’ve probably realized that the majority of hearing loss information around the web is centered around high frequency hearing loss. This is because high frequency losses are more common and more easily understood. In addition, because almost all of the training that hearing providers receive is with regards to flat losses or high frequency losses, how to properly fit a low frequency hearing loss can be mystifying sometimes. The low frequencies are where a lot of the volume of sound comes from, so if the low frequencies are overamplified by a hearing aid, you really run the risk for “masking” out all the other sounds that you do want to hear. In cases like this, Real Ear Measurement can be a very valuable tool. If you do end up going the hearing aid route (which is often times the only option), make sure you get a hearing aid with at least 6 channels- you’re going to need something good.
If you’d like a free phone consultation with a licensed hearing provider, please feel free to call us at 800-731-6794.