CFA Fitting Ranges

Earpieces incorporating continuous flow adapter (CFA) bore and vent configurations can significantly enhance the success of your hearing instrument fittings, providing smooth, comfortable, high-frequency amplification. CFA earpieces have been shown to:

  • Eliminate the acoustic problems created by pinched or crimped tubing
  • Allow users to easily clean and maintain earpieces
  • Eliminate the need to insert acoustic dampers in the tubing to smooth out the frequency response

The accompanying audiograms are based upon several years of research on earmold boring and venting. Use them to assist you in choosing the best CFA earpieces for your patients hearing instruments. Bore and vent options can be selected to match your desired acoustics.

Audiogram 1. Bore #1 with MVP 
Does not increase highs.
Comes standard with a MVP.
Audiogram 2. Bore #1, no vent
Does not increase highs.


Audiogram 3. Bore #2, no vent
Flared sound bore increases highs slightly between 2 and 5 kHz.
Audiogram 4. Bore #4, no vent
Increases highs 10 to 20 dB over conventional earpieces between 2 and 5 kHz and smooths peaks and valleys. If feedback occurs, simply remove the CFA and replace it with a reverse curve adapter.


Audiogram 5. Bore #2 with MVP
Flared sound bore increases highs slightly between 2 and 5 kHz. Comes standard with a MVP.
Audiogram 6. Bore #3 with MVP
Stepped sound bore increases highs 8 to 12 dB between 2 and 5 kHz. Comes standard with a MVP.


Audiogram 7. Style No. 12 only. Bore #4 Micro CROS
Reduced canal diameter increases comfort. Heel area of earmold left full for a MVP. This style increase highs 10 to 20 dB over conventional earpieces between 2 and 5 kHz. Feedback can occur with the use of instruments that promote high-gain, high-frequency improvements.
Audiogram 8. Style No. 52 only. Bore #4 Micro CROS
Non-occluding earmold allows lows to enter naturally. Increases highs 10 to 20 dB over conventional earpieces between 2 and 5 kHz. Feedback can occur with the use of instruments that promote high-gain, high-frequency improvements.


Audiogram 9. Style No. 10 only. Bore #5 with MVP
Cuts highs 8 to 12 dB and increases lows slightly. Comes standard with a MVP and a reverse curve adapter.
Audiogram 10. Bore #5-Long canal, no vent
Cuts highs 8 to 12 dB and increases lows slightly. Comes standard with a reverse curve adapter.

Note: CFA audiograms 7 and 8 are open CROS style earpieces.
Feedback can occur with the use of instruments that promote high-gain, high-frequency improvements.
Audiograms 7, 8 and 9 are not guaranteed against feedback.