From the Research
A cookie bite audiogram is primarily caused by genetic factors, specifically mutations in genes that affect the inner ear's function, as well as other potential causes such as ototoxic medications, noise exposure, and systemic conditions like autoimmune disorders, as supported by the most recent study 1. This pattern of hearing loss, characterized by a U-shaped dip in the mid-frequencies on an audiogram (resembling a bite taken out of a cookie), typically results from sensorineural hearing loss affecting the cochlea. The most common cause is hereditary hearing loss, often with an autosomal dominant inheritance pattern. Other potential causes include:
- Certain ototoxic medications that damage hair cells in the cochlea
- Noise exposure that specifically affects mid-frequency hearing
- Some systemic conditions like autoimmune disorders that can target the inner ear The condition develops because the hair cells responsible for detecting mid-frequency sounds (typically 500-2000 Hz) are more vulnerable in affected individuals. These frequencies are crucial for understanding speech, which is why people with cookie bite audiograms often struggle with conversation despite having relatively better hearing at lower and higher frequencies. The condition is usually bilateral and symmetrical, and while it may be present from birth, it's often progressive and may not be noticed until later in life when communication difficulties become apparent, as noted in studies 2, 3. Additionally, research has shown that cochlear synaptopathy, which can be caused by exposure to loud noise or ototoxic drugs and aging, can also contribute to sensorineural hearing loss and perceptual abnormalities, including speech-in-noise difficulties, tinnitus, and hyperacusis 4. However, the most recent study 1 suggests that a cookie-bite audiogram shape has low sensitivity and positive predictive value in stratifying patients carrying putative loss-of-function variants in known hearing loss genes, and therefore should not be used to screen adults for possible genetic testing. It's also important to consider that genetic factors, epigenetics, and the use of ototoxic drugs can cause loss of hair cells and their related primary neurons, leading to sensorineural hearing loss, as discussed in 2. Overall, the causes of a cookie bite audiogram are complex and multifactorial, and a comprehensive approach is necessary to diagnose and manage this condition.