FONIX FP40 Portable Hearing Aid Analyzer
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Appendix H: Probe SPL Mode Description
The Target IG is converted to the Target SPL in the following steps.
1. Add the source level for Aided curve 2.
2. Interpolate from 10 frequency to 80 frequency curve frame.
3. Add the AVG Unaided ear response REUR in Table 1.
4. If Aided 2 is composite, subtract 10.7 dB from each frequency. If Aided 2 is Speech
Weighted tone, add 2.1 dB to each frequency.
5. If Aided 2 is Speech Weighted, subtract the Speech Weighting in Table 2.
The complete formula is then:
Target SPL = Target IG + CRV2 AVG REUR
(If Aided2 is composite) - 10.7 dB - Speech Weighting.
(If Aided2 is speech tone) + 2.1 dB - Speech Weighting.
• To convert the HTL and UCL from HL to SPL:
Add the corrections in Table 3.
• To predict UCL’s (HL) given the HTL (HL):
Use Table 4 to convert from HTL to UCL.
