How to Read an Audiogram Eric D. Baum, MD Connecticut Pediatric Otolaryngology Madison · North Haven · Shelton · Yale-New Haven Children’s Hospital Some Caveats • Patient participation is key –Limits how much you get –Can you trust it? • Some oddball tests –A legacy of older days –Stick to the core stuff Pure Tone Audiogram • Human hearing: 20 to 20,000 Hz • Speech 500 to 2000 Hz • A normalized scale Different Sounds and Hearing Loss How Severe is Severe? www.cohclear.com Two Categories of Hearing Loss • Conductive – Mechanical issue – Problem getting sound where it needs to go • Sensorineural – Problem once it gets there – “Nerve hearing loss” • Also includes cochlea and brain The two types are additive Can’t Quite Test Them Separately • They are additive • Air Conduction – The whole system: SN + C • Bone Conduction – Bypasses conductive: SN • The Difference: C – “Air-bone gap” It Gets Confusing Multiple Tests • Start with pure tones • Sketch it yourself – Separate ears • Check sides – Swapped like xrays – But not always Know Your Symbols • Generally uniform – But check legend • Some less important – Don’t get distracted • If “masked” is present, use that Normal Hearing Right Left L>R Conductive Hearing Loss Right Left Symmetrical Downsloping Sensorineural Hearing Loss Right Left Profound Left Sensorienural Hearing Loss Right Left Watch for Masking! Right Left Right Mixed Hearing Loss Right Left Normal Hearing • Look at SRT (speech reception threshold) • Look at tympanograms – Curves – Ear canal volume Conductive Hearing Loss • Pure CHL, L>R • Compare SRT to Pure Tone Average (PTA) • What might explain CHL? – Flat tympanogram – Normal volume Types of Tympanograms You Should Ignore • Acoustic reflexes • Otoacoustic emissions (all flavors) • Anything that looks like this: