SPHR 4/588 - Advanced Audiology
dB HL Tutorial

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To convert a value from the HL scale to the SPL one simply adds the reference value to the HL value. For example, if I wish to define the SPL level of a 20 dB HL 4000 Hz. pure tone I would add the reference value (i.e., 10.5) to the dB HL value.

20 ( the dB HL value) + 10.5 (4000 Hz. reference value) = 30.5 dB SPL

Conversely, to convert from SPL to HL you must subtract the 0 dB HL reference value from the SPL value. The dB HL value for a 43.5 dB SPL 500 Hz. pure tone would equal:

43.5 (dB SPL value) - 13.5 (500 Hz. reference value) = 30 dB HL

 

Frequency (Hz.)
125
250
500
1000
2000
3000
4000
6000
8000
TDH 49,5
47.5
26.5
13.5
7.5
11.0
9.5
10.5
13.5
13.0