Differences between NAL-NL2 and Adaptive Phonak Digital

Hearing Aids
43

You can re-derive the CR by noting that the input curves are 15dB apart.

At 250Hz the output curves are 15db or 14dB apart so CR is 1.0 or 1.1.

At 4kHz, the NAL2 curves are: 50-65dB = 8dB; 65-80dB = 5dB. 50-80dB (30dB) is compressed to 13dB.

  • 50-65dB = 8dB , CR=1.9
  • 65-80dB = 5dB , CR = 3.0
  • 50-80dB = 13dB, CR = 2.3

This gradual rise of CR with level is useful and natural. In music studio dynamic control they say “soft knee” or “Over Easy(r)”.

44

I presume this is DSL v5 (for adults). Correct?

45

Correct!

And here are some more characters to keep the forum software happy.

2 Likes
46

Thank you so much for your post. I will try NAL-NL1 tonight :slight_smile:

48

You confused me with this interpretation. Especially for compression.

I think it’s the other way around. The highest compression in these diagrams is with DSL because the curves of the loudest and quietest input are closest, ie. the most compressed.
Accordingly, NAL-NL1 has higher compression than NAL-NL2, and it is especially higher at high frequencies where the NL1 curves almost overlap at high frequencies.