How to Read an Audiogram. An audiogram is a chart of a persons hearing ability. The Audiogram or hearing test measures the softest sound you can hear. The softest level at which you can hear a sound is called the threshold. The degree of hearing loss is measured in dB for defined key frequencies. The frequency is measured in Hertz, abbreviated with Hz. Slight hearing loss is defined as hearing thresholds in the range 20 to 25 dB. Mild hearing loss is defined as hearing thresholds in the range 26 to 40 dB. Moderate hearing loss is defined as hearing thresholds in the range of 40 to 55 dB. Moderately to severe hearing loss is defined as hearing thresholds in the range of 56 to70 dB. Severe hearing loss is defined as hearing thresholds in the range of 71 to 90 dB. Profound hearing loss is defined as hearing thresholds above 90 dB. The audiogram or hearing test helps you match your hearing loss to a Hearing Aid Suggested Fitting Range, or the best Hearing Aid for your hearing loss.