It will give you a brief idea about how to read audiometry...specially designed for MBBS students

1. INTERPRETATION OF PTA(PURE TONE AUDIOMETRY)
1.PTA is so calibrated that the hearing of a normal person,both for air and bone conduction,is at 0 db and
there is no A-B gap,while the tuning fork test normally shows AC>BC
2. Usually frequencies of 250-8000 Hz are used in testing because this range represents most of the
speech spectrum, although the human ear can detect frequencies from 20-20,000 Hz. Some children can
detect even higher frequencies. (High frequency audiometry 8K to 20K is done for detection of
ototoxicity)
3.If BC loss is >25 db,there is definitely SN hearing loss.
➢ A loss of higher frequencies(Sloping curve) is commonly seen in presbycousis.
➢ A loss of lower frequencies(Rising curve) is characteristic of Meniere’s disease.
➢ A sharp dip at 4000 Hz(Both AC and BC) seen in Noise induced hearing loss.
4.If A-B gap is >20 db,there is definitely Conductive hearing loss.
➢ Horizontal curve seen in wax impaction.
➢ Sharp dips in BC curve which is max at 2000 Hz(Carhart’s notch) seen in Otosclerosis.
5.If both 3 and 4 is present,there is mixed type of hearing loss.
6. Degree of hearing loss based on PTA:
• Normal:
0–15 dB HL (infant)
0 - 25 dB HL (adult)
• Mild:
26 – 40 dB HL
• Moderate:
41 – 54 dB HL
• Moderate to severe:
55 – 75 dB HL
• Severe:
76 – 90 dB HL
• Profound:
>90 dB HL

2. Examples:
1.Noise-induced hearing loss

3. 2.Otosclerosis