11_HL to SPL transform

Question 1

Which size of coupler are the RETSPL and RECD referenced to for insert phones?

Answer 1

2 cc SPL

Question 2

Finish the equation:

ER3 + ____ + _____=Real Ear SPL

Answer 2

RECD

RETSPL

Question 3

Finish the equation:

TDH + _____ = Real Ear SPL

Answer 3

REDD (real ear to dial difference)

- used since the residual volume is larger (6cc) than inserts, but there is no clinical measurement of a 6cc RECD

Question 4

Finish the equation:

SF + _____ + ____ = Real Ear SPL

Answer 4

REUG

RETSPL

Question 5

Which size of coupler are the RETSPL and RECD referenced to for TDH transducers?

Answer 5

RETSPL is in 6 cc SPL
RECD is referenced to 2c SPL, so we can’t use it without a correction
-> use REDD (real ear to dial difference)
- measured by placing probe tube, setting audiometer to 70 dB HL, placing headphones, measuring RE SPL across frequencies, then subtracting 70 dB SPL

Question 6

How is the real ear to dial difference (REDD) measured?

Answer 6

• place probe tube
• set audiometer to 70 dB HL
• place headphones
• measure RE SPL across frequencies
• subtract 70 dB HL

Question 7

How do RETSPL and RECD measurements differ for sound field, compared to ER3 and TDH?

Answer 7

• RETSPL is in sound field by azimuth

- RECD is irrelevant b/c ear is not occluded during audiometry

Question 8

Since RECD is irrelevant in Sound Field (SF) measurement for Real Ear SPL, what do we use instead?

Answer 8

REUG - real ear unaided gain
- The open ear response is measured and converted to gain (REUG)

Steps:

• match azimuth
• HL + RETSPL + REUG = RE SPL

Question 9

Why does it usually not make sense to use SF to calculate RE SPL?

Answer 9

Because you can’t measure just one ear in sound field - you need to plug one ear, and if you can plug ears, you might as well just do ER2